RULING ON DEFENDANT'S MOTION TO EXCLUDE DOCTOR METZGER'S STUDY AND PROFFERED OPINION TESTIMONY
Pursuant to Connecticut General Statutes § 52-572M et seq.,Plaintiff Cynthia Perkins ("Ms. Perkins") has brought a productsliability action against defendant Origin Medsystems Inc. ("Origin"), themanufacturer of a surgical fastening device ("the Tacker").1 Ms.Perkins alleges that she has suffered injuries proximately caused by theuse of the Tacker in her 1996 laparoscopic hernia operation. PlaintiffMark Perkins asserts a claim for loss of consortium.2 In support ofher claim, Ms. Perkins intends to call as a witness, Dr. Deborah A.Metzger, Ms. Perkins' initial treating physician and retained expert inthe fields of female chronic pelvic pain3 and laparoscopic herniarepair surgery.4 Based on her education, training, and extensiveclinicalPage 2experience, Dr. Metzger is prepared to testify that the Tacker causesunnecessary post-operative pain in women experiencing chronic pelvicpain, and did in fact injure Ms. Perkins, who suffers from chronic pelvicpain. In support of Dr. Metzger's proffered opinion testimony, Ms. Perkinsseeks to introduce a preliminary retrospective case study (the "Study")that Dr. Metzer prepared based on her treatment of some of her chronicpelvic pain patients.
On March 10, 2003, Origin moved to preclude Dr. Metzger's profferedopinion testimony and the Study pursuant to the principles articulated inDaubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), andits progeny. On June 2 and July 19 and 28, 2003, the court heldevidentiary hearings during which it took evidence and heard, among othertestimony, the testimony of Dr. Metzger and Dr. David Garabrant.5 Forthe reasons set forth below, Origin's motion to exclude the Study isgranted and it's motion to exclude Dr. Metzger's proffered opiniontestimony is denied.
In February 1996, Ms. Perkins visited Dr. Metzger for a fertilityconsultation.6 MetzgerPage 3Dep. at 79; Tr. June 2, 2003 at 115. In April 1996, she returned to Dr.Metzger for treatment of pelvic pain. Deposition of Cynthia Perkins datedNov. 3, 2000 (hereinafter "Perkins Dep. 1") at 96; Tr. June 2, 2003 at115. After conducting a thorough physical exam, Dr. Metzger attributedMs. Perkins' pelvic pain to several sources, including, but not limitedto, endometriosis, ovarian vein syndrome, bilateral ovarian veinligation, and bilateral internal inguinal hernias.7 Tr. June 2, 2003at 31; Metzger Dep. at 84-86, 88. Because she could not directly feel thehernias, Dr. Metzger referred Ms. Perkins to Dr. Ibrahim Daoud, a herniaspecialist, to confirm her diagnosis. Tr. June 2, 2003 at 31. Dr. Metzgerregularly worked with Dr. Daoud. Id. Dr. Daoud agreed that a herniaoperation was appropriate and, in June 1996, he performed laparoscopicsurgery on Ms. Perkins to repair the hernias.
As part of the surgery, Dr. Daoud used the Tacker to affix a gortexmesh over her hernias. Perkins Dep. 1 at 107; Deposition of Dr. Daoud,dated Dec. 1, 2000 at pp. 37-38.8 During the same procedure, Dr.Metzger performed an ovarian vein ligation to assist in relieving some ofthe pelvic pain. Metzger Dep. at 88-89; Tr. June 2, 2003 at 118.
On October 14, 1996, Ms. Perkins returned to Dr. Metzger, andcomplained, in relevantPage 4part, of localized pain at the site of the implanted tacks. Id. at 94.9As she does with all of her patients, Dr. Metzger conducted a thoroughphysical exam of Ms. Perkins, eliminating potential sources for herparticular pain. The physical exam included, in part, palpating differentmuscles and nerves in an attempt to reproduce a component of the newlydeveloped pain. Tr. June 2, 2003 at 26.10 In this case, Dr. Metzgereliminated, among other possible sources, a urinary tract infection, andvaginitis. Id. at 126. She was able to reproduce Ms. Perkins' pain bypalpating the tacks. Id. at 94-95. Dr. Metzger then injected Ms. Perkinswith marcaine,11 a long-lasting local anesthetic, to determine if thepain ceased upon injection. Id. at 95; Tr. June 2, 2003 at 126. After thefirst injection, the pain subsided for approximately three days. Tr. June2, 2003 at 126. After the second injection, the pain subsided for only 24hours. Id. Dr. Metzger's experience has been that if the injections aregoing to ameliorate the pain by desensitizing the nerves to the painfulstimuli, then with each injection, the length of pain relief gets longerand longer until thePage 5pain does not return. Tr. June 2, 2003 at 126.
Dr. Metzger recommended removing Ms. Perkins' tacks based on Ms.Perkins' complaints of localized pain at the site of the tacks, the factthat palpating the tacks reproduced the pain, Dr. Metzger's decreasingability to subdue the pain with marcaine, and on her clinical experiencein having success with treating other patients with similar symptoms byremoving the tacks.12 Id. at 96. Because there were so many tacksinvolved, and some of the tacks were hard to find, it took numerousoperations between November 1996 and February 2000 to remove all of Ms.Perkins' tacks.13 After the last tacks were removed in February2000, Ms. Perkins claims that she did not experience any more pelvic painat the site of the tacks. Perkins Deposition, Nov. 14, 2002 (hereinafter"Perkins Dep. 2") at 33; Tr. June 2, 2003 at 60.
In response to experiences like those of Ms. Perkins, Dr. Metzgerceased using surgical fastening devices in hernia operations.14 Dr.Metzger also decided to do a retrospective case study to examine thefrequency with which patients developed pain as a result of surgicalPage 6fastening devices, requiring surgical removal of such devices. Tr. June2, 2003 at 37. In the Study, Dr. Metzger sets forth some of her clinicalfindings with respect to hernia repair operations. She specificallyreports on two issues: (1) the success of the hernia repair operations incuring the patient's hernia pain as a function of the medical fasteningproduct used in the surgery, and (2) the need for re-operation for paincaused by the surgical product itself. In the Study, Dr. Metzger compiledinformation on three groups of women: one group had gortex mesh placedover the hernia(s) without any fasteners, one group had gortex meshaffixed with tacks, and the third group had gortex mesh affixed withstaples. In her deposition, Dr. Metzger states that, of the 2615patients who had gortex mesh affixed with tacks, 17 developedpost-operative pain at the location of those tacks, requiring surgicalremoval of the tacks. Metzger Dep. at 53. Four of those women requiredmultiple surgeries to remove the tacks. Id. In addition, of the 82 womenwho had their hernias repaired with gortex mesh and staples,approximately 15 required surgery to remove the staples. Id. at 54.According to Dr. Metzger, "[t]he study shows that the rate of incidenceof post-surgical problems for women where tacks were used is higher thanthe rate when staples or marlex mesh are used. [Dr. Metzger] believesthat these differences are a function of the depth and strength at whichthe tacks are inserted using the Tacker, which interferes with the normalmovement of tissues in the area where the tacks are located, therebycausing pain. The depth and strength of the tack insertions also makessurgical removal of the tacks difficult." Expert Report of Dr. DeborahA. Metzger at 1.Page 7
Ms. Perkins has alleged various causes of action under the ConnecticutProducts Liability Act, §§ 52-572m et seq. In support of her claims,Ms. Perkins seeks to admit the opinion testimony and Study of Dr.Metzger. Dr. Metzger's proffered opinion testimony states "that use ofthe Tacker on women suffering from chronic pelvic pain creates anunreasonable and unacceptably high risk that the implanted tacks willcause the patient to suffer pain that cannot be effectively treated withlocal anesthetic injections or other methods, such that the patients mustundergo surgical removal of the tacks in order to obtain relief." ExpertReport of Dr. Deborah A. Metzger at 1. In addition, Dr. Metzger isprepared to testify that the "[u]se of the Tacker in Cynthia Perkins'hernia repair caused Ms. Perkins to suffer from debilitating pain anddepression for an extended period of time, until all of the tacks werefinally removed. Because of her pain caused by the Tacker, Ms. Perkinswas required to undergo extensive medical treatment, including but notlimited to multiple surgeries, trigger point injections, and the use ofnarcotic and anti-depressant medications . . . " Id. at 2.
Origin argues that Dr. Metzger's proffered opinion testimony and theStudy cited in support thereof fail to meet the applicable standardsgoverning the admissibility of expert testimony and reports underDaubert and its progeny.
A. The Standard for Admitting Proffered Expert Testimony
The proponent of expert testimony has the burden of demonstrating by apreponderance of the evidence, see Daubert, 509 U.S. at 592 n.10, that thetestimony is competent, relevant, and reliable. Koppell v. New York StateBoard of Elections, 97 F. Supp.2d 477, 479 (S.D.N.Y. 2000); Union Bank ofSwitzerland v. Deutsche Financial Services Corp., 2000 WL 178278 at *8Page 8(S.D.N.Y 2000) (internal citations omitted) (citing Bourjaily v. UnitedStates, 483 U.S. 171 (1987)). If the expert is deemed competent(otherwise referred to as "qualified"), an issue not in dispute in thiscase, the trial court must then determine, pursuant to its "gatekeeping"function, whether the proffered expert testimony is "relevant" and"reliable." See Advisory Committee Notes, 2000 Amendments, Fed.R.Evid. 702(noting that trial judges have "the responsibility of acting asgatekeepers to exclude unreliable expert testimony").
Evidence is relevant if the testimony "ha[s] any tendency to make theexistence of any fact that is of consequence to the determination of theaction more probable or less probable than it would be without theevidence." Amorgianos v. National R.R. Passenger Corp., 303 F.3d 256, 264(2d Cir. 2002) (alteration in original) (citing Campbell v. Metro. Prop.& Cas. Ins. Co., 239 F.3d 179, 184 (2d Cir. 2001) (quotingFed.R.Evid. 401)); Daubert, 509 U.S. at 591 ("Expert testimony which doesnot relate to any issue in the case is not relevant and, ergo,non-helpful. . . . Rule 702's `helpfulness' standard requires a validscientific connection to the pertinent inquiry as a precondition toadmissibility."). If the evidence is relevant, the trial court must thendetermine "whether the proffered testimony has a sufficiently `reliablefoundation' to permit it to be considered" by the trier of fact.Amorgianos, 303 F.3d at 265 (quoting Daubert, 509 U.S. at 597).16
Rule 702 provides guidance to the trial court in determining whetherthe proffered expert testimony is sufficiently reliable. Rule 702 states,in relevant part, that expert testimony may bePage 9considered reliable if: (1) "the testimony is based on sufficient factsor data;" (2) the expert's technique or methodology in reaching theconclusion is considered reliable; and (3) the expert has applied themethodology reliably to the facts of the case. Fed.R.Evid. 702.Moreover, in order for the testimony to be admissible, all threecomponents of Rule 702's reliability analysis must be met. Amorgianos,303 F.3d at 267 ("The reliability analysis applies to all aspects of theexpert's testimony: the methodology, the facts underlying the expert'sopinion, the link between the facts and the conclusion.") (quoting In rePaoli R.R. Yard PCS Litig., 35 F.3d 717, 745 (3d Cir. 1994)).
In Daubert, the Supreme Court set out a list of non-exclusive factorsthe trial court may consider in determining whether an expert's reasoningor methodology is reliable: (1) whether the theory or technique on whichthe expert relies has been tested — that is, whether the expert'stheory can be challenged in some objective sense, or whether it isinstead simply a subjective, conclusory approach that cannot reasonablybe assessed for reliability; (2) whether the theory or technique has beensubject to peer review and publication; (3) the known or potential rateof error of the technique or theory when applied; (4) the existence andmaintenance of standards controlling the technique's operation; and (5)whether the theory or method has been generally accepted by thescientific community. See Daubert, 509 U.S. at 593-94.
No single factor is necessarily dispositive of the reliability of aparticular expert's testimony, because a trial court need only "considerthe specific factors identified in Daubert where they are reasonablemeasures of the reliability of expert testimony." Kumho Tire Co., Ltd.v. Carmichael, 526 U.S. 137, 150 (1999). The test of reliabilitytherefore is a "flexible" one depending on the "nature of the issue, theexpert's particular expertise, and the subject of hisPage 10testimony." Id. (quoting Daubert, 509 U.S. at 593).17
If the court finds the methodology reliable, the court must thendetermine if the methodology was reasonably applied to the facts of thecase. Amorgianos, 137 F. Supp.2d 147, 162 (E.D.N.Y. 2001). In making thisassessment, the court's inquiry under Daubert must focus not on thesubstance of the expert's conclusions, but on whether those conclusionswere generated by a reliable methodology. See Daubert, 509 U.S. at 590,595; Amorgianos, 137 F. Supp.2d at 162 (E.D.N.Y. 2001). Nevertheless, anexpert's testimony must be held inadmissible if "there is simply toogreat an analytical gap between the data and the opinion proffered," suchthat the opinion is "connected to the existing data only by the ipsedixit of the expert." Amorgianos, 303 F.3d at 266 (quoting GeneralElectric Co. v. Joiner, 522 U.S. 136, 146 (1997)); see also Mancuso v.Consolidated Edison Co. of New York, Inc., 967 F. Supp. 1437, 1441(S.D.N.Y. 1997) ("[E]xpert testimony should be excluded if it isspeculative or conjectural, or if it is based on assumptions that are sounrealistic and contradictory as to suggest bad faith or to be in essencean apples and oranges comparison.") (internal citations omitted) (quotingBoucher v. Suzuki Motor Corp., 73 F.3d 18, 21 (2d Cir. 1996)). At thesame time, the court should afford the expert some deference because a"minor flaw in an expert's reasoning or a slightPage 11modification of an otherwise reliable method will not render an expert'sopinion per se inadmissible." Amorgianos, 303 F.3d at 267.
In determining reliability, the tendency toward limiting the exclusionof expert testimony "accords with the liberal admissibility standards ofthe federal rules and recognizes that our adversary system provides thenecessary tools for challenging reliable, albeit debatable, experttestimony." Id.; Daubert, 509 U.S. at 596 ("Vigorous cross-examination,presentation of contrary evidence, and careful instruction on the burdenof proof are the traditional and appropriate means of attacking shaky butadmissible evidence."). Thus, it is not surprising that "[a] review ofthe case law after Daubert shows that the rejection of expert testimonyis the exception rather than the rule." Advisory Committee Notes, 2000Amendments, Fed.R.Evid. 702.
In short, the gatekeeping responsibility of the trial court is not toweigh the correctness of an expert's opinion, or to choose betweenconflicting opinions, or to analyze and study the science in question inorder to reach its own conclusions from materials in the field.Ultimately, it is the role of the trial court as gatekeeper to
ensure the reliability and relevancy of expert testimony. It is to make certain that an expert, whether basing testimony upon professional studies or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.Kumho Tire, 526 U.S. at 152.
B. Admissibility of The Study
Origin argues that the Study is unreliable because: (1) the Study isnot supported in the medical literature, (2) the Study has not been andcannot be tested; (3) the Study has not been subjected to peer review andpublication; and (4) Dr. Metzger's research methods introducedPage 12substantial sources of error into the Study. In support of its position,Origin offers the testimony of Dr. David Garabrant, who testified thatthe Study is not reliable because: (1) Dr. Metzger failed to make anyeffort to determine the statistical significance of her purportedfinding, that is, whether the results were influenced by random error;(2) Dr. Metzger made no effort to control for bias in the Study; (3) Dr.Metzger made no real attempt to control for the influence of potentialconfounding factors; (4) the purported findings based on a comparison ofthe patients on whom tacks and staples were used and those on whom nofastening device was used creates a completely unreliable picture becausethe average time between surgery and follow up in the first group wassignificantly longer than the average time between surgery and follow upin the second group.
The court finds merit to most of the criticisms articulated by Dr.Garabrant at the Daubert hearing. See Tr. June 2, 2003 at 153-216; seealso Metzger Dep. at 314 (admitting to potential observer bias andpotential confounding factors); Tr. June 2, 2003 at 83 (admitting studywas not randomized). In addition, the court finds it unnecessary toaddress Dr. Garabrant's criticisms at this time because, by her ownadmission, Dr. Metzger described the Study as "a work in progress," "apreliminary draft," and "not complete." See Metzger Dep. at 53; see Tr.July 28, 2003 at 14, 40; Tr. June 2, 2003 at 38-39 (Testifying that,although it was her intention to attempt to put that paper in publishableform, she did not have sufficient time to complete her work). Moreover,Dr. Metzger admitted that she did not rely on the Study in forming heropinions in this case. Tr. July 28, 2003 at 44 (testifying that her"opinions [on causation] were derived before the Study was undertaken");Expert Report of Dr. Deborah A. Metzger at 1 (noting that herobservations "during the course of treating patients in private practice. . . were then confirmedPage 13and quantified in the Study"). Accordingly, the Study will be excluded.
C. Admissibility of Dr. Metzger's Opinion Testimony18
To satisfy her burden at trial, the parties agree that Ms. Perkins mustdemonstrate general causation, that is, that the Tacker is capable ofcausing unforseen post-operative pain in women experiencing chronicpelvic pain, as well as specific causation, that is, that the Tacker didin fact cause her injuries. In re Joint E. & S. Dist. AsbestosLitig., 52 F.3d 1124, 1131 (2d Cir. 1995) (recognizing plaintiff's burdenof proving general and specific causation in a products liability toxictort case); DeLuca v. Merrell Dow Pharmaceuticals, Inc., 911 F.2d 941,958 (3d Cir. 1990) (testimony must be able to support a jury findingboth: (i) that the drug can produce birth defects and (ii) that the drugmore likely than not caused the birth defects in this particular case);Blanchard v. Eli Lilly & Co., 207 F. Supp.2d 308, 314 (D. Vt. 2002)(noting that in order to prevail on their claim against drug manufacturerof Prozac, the plaintiffs must prove that Prozac is capable of causingand in fact did cause the deaths at issue).Page 14
1. General Causation
Origin does not challenge Dr. Metzger's qualifications to testify as anexpert in chronic pelvic pain or laparoscopy surgery, but instead arguesthat Dr. Metzger's opinions on causation should be excluded because herreasoning and methodologies are unreliable. I disagree.
Under Daubert and Rule 702, the district court has wide discretion todetermine whether the particular circumstances lend themselves to aphysician's ability to offer a reliable opinion. Kumho Tire Co.,526 U.S. 137, 150 ("[T]he factors identified in Daubert may or may not bepertinent in assessing reliability, depending on the nature of the issue,the expert's particular expertise, and the subject of his testimony.")(internal quotations omitted); Westberry v. Gislaved Gummi AB,178 F.3d 257, 261 (4th Cir. 1999) (recognizing that the particularfactors that bear on the validity of the expert's testimony will dependupon the unique circumstances of the expert testimony involved). On thispoint, the Second Circuit's holding in McCullock v. H.B. Fuller Co.,61 F.3d 1038 (2d Cir. 1995), is instructive.
In McCullock, the Second Circuit affirmed the admission of Dr.Fagelson's testimony that fumes from glue caused the plaintiff's throatpolyps, despite the physician's inability to cite any medical literatureidentifying glue fumes as a general casual agent of the plaintiff'sinjury. McCullock, 61 F.3d at 1043-44; citing Carroll v. Morgan,17 F.3d 787, 790 (5th Cir. 1994) (holding that a doctor was qualifiedunder Daubert to give an expert opinion on a standard of medical carebased on thirty years of experience as a practicing, board-certifiedcardiologist and his review of the medical records), and Hopkins v. DowCorning Corp., 33 F.3d 1116, 1125 (9th Cir. 1994) (holding that thedistrict court properly admitted expert testimony under Daubert that wasbased on, inter alia, the doctor's clinical experience and review of themedical records); seePage 15also Westberry, 178 F.3d at 262 (holding that a reliable differentialdiagnosis alone provides valid foundation for causation opinion, evenwhen no epidemiological studies, peer-reviewed published studies, animalstudies, or laboratory data are offered in support of the opinion);Pipitone v. Biomatrix, Inc., 288 F.3d 239, 245-46 (5th Cir. 2002)(holding that lack of literature on injection-related infections of jointdid not undermine expert's hypothesis because trial court could rely onfirst-hand observations and professional experience to assess expert'sreliability); Santoro v. Signature Constr. Inc., 2002 WL 31059292, at *4(S.D.N.Y. 2002) (recognizing that "treating physicians have routinelybeen permitted to testify to determinations that they made in the courseof providing treatment regarding the cause of an injury and itsseverity"); Reyes v. Delta Dallas Alpha Corp., 2000 WL 526851, *2 (May2, 2000) (admitting doctor's expert testimony "based on a number offactors, including his care and treatment of plaintiff, and his ownpractical experience"); Canino v. HRP, Inc., 105 F. Supp.2d 21, 31(N.D.N.Y. 2000) (allowing opinion "based on years of education, trainingand clinical experience . . . [and] specific treatment of plaintiff").
In this case, Dr. Metzger grounds her opinion on a range of factors,including her education, training, extensive clinical experience intreating chronic pelvic pain patients, as well as her care and treatmentof Ms. Perkins. Dr. Metzger's knowledge and training are unquestionablyimpressive; she has had a long and distinguished medical career, whichincludes prestigious academic positions, extensive publications and aunique expertise in two fields at issue in this case, chronic pelvic painand laparoscopic surgery.19 Her practical experience includesPage 16treating thousands of chronic pelvic pain patients as well as performingnumerous tack removal operations. Her methodology, differentialdiagnosis, is a standard scientific technique of identifying the cause ofa medical problem. Martin v. Shell Oil Co., 180 F. Supp.2d 313, 320 (D.Conn. 2002); McCullock, 61 F.3d at 1044 (describing differentialdiagnosis as requiring "listing possible causes, then eliminating allcauses but one"); In re Paoli, 35 F.3d at 758 (3d Cir. 1994) (noting thatdifferential diagnosis "generally is a technique that has widespreadacceptance in the medical community, has been subject to peer review, anddoes not frequently lead to incorrect results"); Zwillinger v. GarfieldSlope Housing Corp., 1998 WL 623589, *19 (E.D.N.Y. 1998) (explaining thatdifferential diagnosis typically includes a physical examination,clinical tests, and a thorough case history); see also Westberry, 178F.3d at 262-63; Baker v. Dalkon Shield Claimants Trust, 156 F.3d 248,252-53 (1st Cir. 1998); Glaser v. Thompson Med. Co., 32 F.3d 969, 978(6th Cir. 1994).
Differential diagnosis is a reliable basis to prove general causationin this circuit. Plourde v. Gladstone, 190 F. Supp.2d 708, 722 (D. Vt.2002) (citing McCullock, 61 F.3d at 1044) (explaining that "lack oftextual authority" on the issue of general causation "go[es] to theweight, not the admissibility" of an expert opinion, when the expert hasperformed a reliable differential diagnosis); see also Pick v. AmericanMedical Systems Inc., 958 F. Supp. 1151, 1160-63 (E.D. La. 1997)(permitting Dr. Campbell to opine, on the basis of differentialdiagnosis, that thePage 17defendant's product may be responsible for the patient's symptoms becausehe was able to test his hypothesis by examining a series of individuals,their exposure, or lack thereof to the defendant's product, and theircomparative symptoms); compare Hall, 947 F. Supp. at 1414 (noting that "asingle differential diagnosis is a scientifically invalid methodology"for the purpose of demonstrating general causation"); In re Breast PlantLitigation, 11 F. Supp.2d at 1230 (finding expert's conclusion thatsilicone auto-immune diseases as unreliable in absence of proof thatsilicone can actually cause the plaintiff's symptoms); Soldo, 244 F.Supp.2d at 516 (finding expert's opinion, based solely on differentialdiagnosis, as unreliable because it "ignores the substantial evidencethat a discernible cause is never identified with respect to asignificant number of strokes, despite careful evaluation"); Cavallo v.Star Enterprise, 892 F. Supp. 756, 771 (E.D. Va. 1995) (disapproving theuse of differential diagnosis to prove general causation in a toxic tortcase because "a fundamental assumption underlying this method is that thefinal, suspected `cause' remaining after this process of elimination mustactually be capable of causing the injury"), aff'd in relevant part,rev'd in part, 100 F.3d 1150, 1159 (4th Cir. 1996), cert. denied,522 U.S. 1044 (1998).
In addition, Dr. Metzger's experience is particularly unique in aproducts liability context because she generally has had the opportunityto observe her patients, prior to the insertion of the surgical tacks,during the time the fixation devices were in place, and after the tackshad been removed. As such, she was able to observe a strong temporalrelationship not just between the defendant's product and the onset ofsymptoms, see Canino, 105 F. Supp.2d at 29-30 (admitting expert opinionthat relies, in part, on "the temporal proximity between the . . .incident and plaintiff's onset of [the disease]"), but also betweenremoval of the defendant's product and thePage 18disappearance of symptoms. See Heller, 167 F.3d at 157 (dismissingexperts' medical causation opinion, in part, because "[n]ot only didHeller's symptoms not appear until at least one or two weeks after theShaw carpeting was installed, but they remained after the carpet wasremoved in May 1994"); Wooley v. Smith & Nephew Richards, Inc.,67 F. Supp.2d 703 (S.D. Tx. 1999) (excluding physician's opinion in partbecause the doctor could "not point out any symptoms occurring after thepedicle screw surgery that did not also exist before the surgery");compare Blanchard v. Eli Lilly & Co., 207 F. Supp.2d at 320 (D. Vt.2002) (excluding Dr. Maltsberger's opinion, on the basis of his clinicalexperience, regarding a casual relationship between Prozac and suicidaltendencies, because, among other things, the doctor had no directclinical experience with patients who have experienced newly emergentsuicidal thoughts, attempted or committed suicide or become violent whiletaking Prozac).
Another factor favoring admissibility is the fact that Dr. Metzger'sopinions were not developed for purposes of litigation, but instead weredeveloped "naturally and directly out of [work she] conducted independentof the litigation." Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311,1317 (9th Cir. 1995) (noting that "the testimony proffered by an expertis based directly on legitimate, preexisting research unrelated to thelitigation provides the most persuasive basis for concluding that theopinions he expresses were `derived by the scientific method'");Prohaska, 138 F. Supp.2d at 437 (noting that "[l]itigation-drivenexpertise has been found to be a negative factor in admissibility"). Dr.Metzger developed her opinion during the course of her medical practice.In fact, she brought her concerns regarding the use of the Tackerdirectly to Origin and to the Food and Drug Administration. In addition,Dr. Metzger has also presented her opinions at medical seminars to otherphysicians. See Cabrera v. Cordis Corp., 134 F.3d 1418,Page 191420-21 (9th Cir. 1998).
In support of its motion to exclude, Origin argues that "[n]o otherphysician or researcher has published so much as a letter to the editorsupporting Dr. Metzger's position on this issue. Despite what Plaintiffsargue about Dr. Metzger's qualifications and experience, this is clearlya case where an expert is offering a novel theory and citing her ownincomplete studies in support of it." See Def. Brief dated June 18,2003. These contentions are rejected.
First, as the Second Circuit stated in McCullock, the "lack of textualauthority" on the issue of general causation "go[es] to the weight, notthe admissibility" of an expert opinion, when the expert has performed areliable differential diagnosis." McCullock, 61 F.3d at 1044.
In the actual practice of medicine, physicians do not wait for conclusive, or even published and peer-reviewed, studies to make diagnoses to a reasonable degree of medical certainty. Such studies of course help them to make various diagnoses or to rule out prior diagnoses that the studies call into question. However, experience with hundreds of patients, discussions with peers, attendance at conferences and seminars, detailed review of a patient's family, personal, and medical histories, and thorough physical examinations are the tools of the trade, and should suffice for the making of a differential diagnosis even in those cases in which peer-reviewed studies do not exist to confirm the diagnosis of the physician.Heller, 167 F.3d at 155.
Second, Dr. Metzger is not basing her opinion on incomplete studies.Although her Study is admittedly incomplete, Dr. Metzger formed heropinions prior to developing the Report. Tr. July 28, 2003 at 44(testifying that her "opinions [on causation] were derived before thestudy was undertaken").Page 20
Third, both Dr. Anthony Luciano,20 who became Ms. Perkins' OB-GYNwhen Dr. Metzger moved from Connecticut to California, and Dr. TerrenceDonahue,21 a doctor Ms. Perkins saw on a referral from Dr. Luciano,stated in their depositions that surgical tacks arePage 21capable of causing post-operative localized pain. See PL Brief dated June1, 2003, Exs. B, C; see also Ex. G, Deposition of Dr. Michael Zinaman,dated March 31, 2003 (not refuting the contention that tacks could casepain); see also Ex. F, Deposition of Dr. Albert Chin, dated April 8, 2003(stating that it "certainly may be the case" that individuals withchronic pelvic pain "might be more sensitive to pain stimuli than thegeneral population"). In addition, the plaintiffs have included medicalabstracts indicating that, at a minimum, a controversy exists in themedical community about the necessity of fixation devices in herniarepair surgeries. See id., Ex. E.
Origin argues next that Dr. Metzger's opinion is not reliably based onher application of differential diagnosis.22 Origin's arguments arerejected in light of McCullock, 61 F.3d at 1044 ("Disputes as to the. . . faults in [the expert's] use of differential etiology as amethodology . . . go to the weight, not the admissibility, of [theexpert's] testimony."); (citing Daubert 509 U.S. at 596 ("Vigorouscross-examination, presentation of contrary evidence, and carefulinstruction on the burden of proof are the traditional and appropriatemeans of attacking shaky but admissible evidence."); see also Golod v. LaRoche, 964 F. Supp. 841, 858 (S.D.N.Y. 1997) ("The fact that thesephysicians are unable to describe the mechanism by which Tegison causedits adversePage 22effects is irrelevant. The mechanisms of both therapeutic and toxiceffects of drugs are often unknown. . . . Just as the mechanism ofefficacy need not be known to support a claim that Tegison causesabatement of dermatological symptoms, so the mechanism of toxicity neednot be known to support an inference of causation based on acceptedclinical methods of diagnosis.").
Origin also argues that if the Study is unreliable then Dr. Metzger'sclinical experience based on her Study must also be unreliable. Statedotherwise, Origin is arguing that Dr. Metzger's opinion based on herclinical experience cannot reasonably be separated from the dataunreliably compiled in the Study. I disagree.
First, the record is clear that the Study is only a preliminarycollection of data, taken on a fraction of her patients. As such,eliminating Dr. Metzger's opinion based on her Study should have noeffect on her opinion based on her years of clinical experience. Second,were the court to accept Origin's contention that Dr. Metzger isprecluded from testifying because her Study is inadmissible, then thecourt would be in the precarious situation of permitting testimony fromdoctors who do not take the initiative to summarize their clinicalexperience, yet precluding testimony from doctors who take the initiativeto analyze their work but who have not yet completed their studies. Assuch, the court would be required to preclude experienced physicians fromoffering opinions in the time period between the commencement of a studyand the completion of the study. "To so hold," the Third Circuit noted inHeller, "would doom from the outset all cases in which the state ofresearch on the specific ailment or causal agent was in its earlystages, and would effectively resurrect a Frye-like bright-linestandard, not by requiring that a methodology be `generally accepted,'but by excluding expert testimony not backed by published (and presumablypeer-reviewed studies)." Heller, 167 F.3d at 155.Page 23
Accordingly, Dr. Metzger's experience, knowledge and training, takentogether with the clinical process she followed, which disclosed acorrelation between placement of tacks and her patient's pain, satisfiesthe Daubert threshold of reliability. Dr. Metzger's opinion is thereforeadmitted to prove general causation.
2. Specific Causation
On the basis of differential diagnosis, Dr. Metzger is prepared totestify that the use of the Tacker in Ms. Perkins' hernia repairs causedMs Perkins to suffer pain that could not be effectively treated withlocal anesthetic injections or other methods, such that she needed tohave the implanted tacks removed in order to obtain relief. Origin doesnot dispute that Dr. Metzger's methodology of differential diagnosisqualifies as a reliable methodology to determine the specific cause ofMs. Perkins' pain. Tr. June 19, 2003 at 15. Rather, Origin argues that,because Dr. Metzger did not reliably apply the methodology to Ms.Perkins, her proffered opinion testimony on specific causation should beexcluded. See id. at 13.
When determining the specific source of an individual patient's pain,differential diagnosis requires the expert to "take serious account ofother potential causes" of the condition. Baker, 2003 WL 22439730, *2n.3; Westberry, 178 F.3d at 265; Turner v. Iowa Fire Equipment Co.,229 F.3d 1202, 1207 (8th Cir. 2000). Although an expert is not requiredto eliminate every potential cause in order for his or her opinion to beadmissible under Daubert, the expert is required to employ eitherstandard diagnostic techniques to eliminate obvious alternative causesor, if the defendant suggests some likely alternative cause of theplaintiffs condition, the expert is required to offer a reasonableexplanation why he or she still believes that the defendant's action orproductPage 24was a substantial factor in bringing about the plaintiff's condition.Munafo v. Metro. Transp. Auth., 2003 WL 21799913, *18 (E.D.N.Y. 2003);Paoli, 35 F.3d 717 at 760; see also Baker, 2003 WL 22439730 *2, n.3;Turner, 229 F.3d at 1209; Kannankeril v. Terminix Int'l, Inc.,128 F.3d 802, 808 (3d Cir. 1997). A strong temporal relationship betweenthe patient's symptoms and exposure to the defendant's product cancertainly assist a physician in offering a reasonable explanation. SeeHeller, 167 F.3d at 158 (noting that "when the temporal relationship isstrong and is part of a standardized differential diagnosis, it wouldfulfill many of the Daubert  factors."). Moreover, the court affordsgreat weight to the testimony of treating physicians. Poust v. HuntleighHealthcare, 998 F. Supp. 478, 496 (D. N.J. 1998) (citing Sprague v.Bowen, 812 F.2d 1226, 1230 (9th Cir. 1987) ("The rationale for givinggreater weight to a treating physician's opinion is that he is employedto cure and has a greater opportunity to know and observe the patient asan individual.").
Origin criticizes Dr. Metzger for failing to account for physical orsexual abuse as a cause of chronic pelvic pain. In response to thiscriticism, Dr. Metzger testified that, although it is helpful to be awareof a patient's history of physical or sexual abuse, such information isonly of limited potential use because approximately 25% of her patientsreport incidents of childhood sexual abuse, which Dr. Metzger believes isabout the incidence of childhood sexual abuse in the general population.Tr. June 2, 2003 at 143. She also testified that it is not her practiceto rely solely on such information if there are other obvious causes ofthe pain. In Ms. Perkins' case, the implanted tacks were a more obviouscause of Ms. Perkins' pain. Dr. Metzger formed her opinion on the basisof her: clinical experience in recognizing a correlation between tacksand localized post-operative pain; Ms. Perkins' description of painsimilar to her other patients in which thePage 25tacks were the source of the pain; conducting a thorough physicalexam in which she eliminated other potential sources of her pain;reproducing Ms. Perkins' pain by palpating the tacks; providing Ms.Perkins temporary-decreasing relief through local anesthetics, andproviding her permanent relief by removing the tacks.
In this case, there is no doubt that Dr. Metzger's performed asufficiently reliable differential diagnosis to permit her to testify asan expert. See Sita v. Danek Medical, Inc., 43 F. Supp.2d 245, 255(E.D.N.Y. 1999) (permitting expert testimony, despite characterizing thedoctor's credibility and reliability of the conclusions he reaches in hisreport as "highly suspect," because "[i]t is not outside the scope ofreason and common sense to conclude that when a medical device fracturesinside of a patient roughly contemporaneously with the time that thepatient starts to complain of pain in the relevant area, that fracturemight well be a substantial factor in causing that pain"); see alsoHeller, 167 F.3d at 158 (noting that "[h]ad the Hellers experienced aprompt reaction at the time the Shaw carpeting was installed inmid-December 1993, and had they suffered no reaction upon return to theirhome after the Shaw carpet was removed in May 1994, this would be thetype of temporal relationship that might reliably support a conclusionthat the carpet was the cause of plaintiff's illness"). Moreover, any"[disputes] as to the strength of . . . [her] use of differentialetiology as a methodology . . . go to the weight, not the admissibility,of [her] testimony." McCullock, 61 F.3d at 1044; Baker, 2003 WL 22439730*2, n.4.
In addition, Dr. Metzger testified that her opinion about the source ofMs. Perkins' pain would not have changed even if she knew that herpatient had experienced prior sexual or physical abuse. Accordingly, evenif the court accepts Origin's proposition that Dr. Metzger's analysis isPage 26flawed due to her failure to consider her patient's history of physicalor sexual abuse, that flaw is not substantial enough that she lacks "goodgrounds" for her diagnosis. See Amorgianos, 303 F.3d at 267. Moreover,her failure to consider Ms. Perkins' history of physical or sexual abusebefore forming an opinion on causation affects the weight of hertestimony, not its admissibility. McCullock, 61 F.3d at 1044 ("Disputesas to the strength of his credentials, faults in his use of differentialetiology as a methodology, or lack of textual authority for his opinion,go to the weight, not the admissibility, of his testimony."); Baker, 2003WL 22439730 *2, n.4.
Therefore, Origin's motion to preclude Dr. Metzger's testimony aboutspecific causation is denied because Dr. Metzger, as Ms. Perkins' treatingphysician, reasonably applied differential diagnosis and has provided areasonable explanation for why she did not consider the defendant'ssuggested alternative source of pain. Under these circumstances, Dr.Metzger's Opinion will not be excluded as unreliable.
For the foregoing reasons, Origin's motion to exclude the Study (doc. #48-1) is GRANTED and it's motion to preclude the proffered opiniontestimony of Dr. Metzger (doc. # 48-1) is DENIED.
It is so ordered.
1. The Tacker is a surgical fastening device that dispenses tacksinto tissues, thereby affixing a surgical mesh.
2. Mr. Perkins' claim depends on the same causation evidence as thatoffered by Ms. Perkins to support her claims. For the sake of simplicity,I will refer hereafter only to Ms. Perkins when discussing plaintiffs'claims.
3. According to Dr. Metzger, chronic pelvic pain is pelvic pain thatlasts three to six months or longer, interferes with a woman's life andis not related to menstrual cramps or bowel function. See Deposition ofDeborah A. Metzger dated December 4, 2000 (hereinafter "Metzger Dep.") at22-23; Daubert Hearing Transcript ("Tr.") June 2, 2003 at 21.
4. Laparoscopic hernia repair is a minimally invasive surgicaltechnique to fix tears in the abdominal wall (muscle) using smallincisions, surgical scopes and a patch (mesh).
5. In addition to the original motion papers and three days ofevidentiary hearings, the parties extensively and exhaustively briefedthis motion. See Plaintiff's Supplemental Memorandum in Opposition toMotion to Exclude Expert Opinion of Dr. Deborah Metzger (doc. # 57);Defendant Origin Medsystems, Inc's. Response to Plaintiff's SupplementalMemorandum in Opposition to Origin's Motion to Exclude Opinions of Dr.Metzger (doc. # 58); Plaintiff's Supplemental Memorandum in Opposition toMotion to Exclude Expert Opinions of Dr. Deborah Metzger (doc. # 67);Plaintiff's Post-Hearing Memorandum in Opposition to Motion to ExcludeExpert Opinions of Dr. Deborah Metzger (doc. # 69); and Origin MedsystemsInc., Post-Hearing Brief in Support of its Motion to Exclude the Opinionsof Dr. Metzger (doc. #71).
6. A small portion of Dr. Metzger's practice consists of fertilitywork. However, all references in this Ruling relate to her chronic pelvicpain patients.
7. Bilateral inguinal hernias are occult hernias, that is, herniasthat generally cannot be observed, palpatated or felt. Tr. June 2, 2003at 120. The laparoscopic procedure allows the physician to see and repairsmall hernias not detected by a physical examination. In addition, theparties do not dispute that Ms. Perkins suffers from chronic pelvicpain.
8. When Drs. Daoud and Metzger first began performing herniaoperations and repairs, they affixed the mesh to the hernia(s) with astapler. Tr. June 2, 2003 at 32. The problem with the stapler was that itrequired a large trocar site opening in the abdomen in order to maneuverthe stapler to affix the mesh. A large trocar site requires the surgeonto cut through a greater amount of tissue in order to affix the mesh,resulting in more trauma to the surrounding tissue, an increased chancefor complications, and a protracted recovery time. Id.
9. In her deposition, Dr. Metzger commented that a patient'sdescription of a pulling or tearing sensation is consistent with thesensation caused by tacks; when a tack is placed in a muscle and themuscle contracts and moves, part of the tack is moving one way, andanother part of the tack is moving another way, resulting in a pulling ortearing sensation.
10. The examination included, but was not limited to, palpatatingnerves around the uretha, bladder and the ureters muscles because,according to Dr. Metzger, "you can tug at the ureters and if that's asource of their pain then you get concerned there is scar tissuesomewhere along the ureter." Tr. June 2, 2003 at 26. In addition, Dr.Metzger would palpate the cul-de-sac because "the cul-de-sac is a spacewhere you can feel modules of endometriosis, another cause of chronicpelvic pain." Id. Dr. Metzger would also press on the ovarian points tosee whether this reproduces a portion of the patient's pain. She wouldfeel around the stomach muscles, as well as look for a reverted uterus.If the patient experienced pain during intercourse, she would perform aQ-tip exam to see if there is pain merely on insertion in intercourse.Id. at 26. She would also feel the adnexa as a potential source of pain.Id. at 27.
11. According to Dr. Metzger, marcaine is actually the brand namefor bupivacaine, which is a long-lasting local anesthetic. Tr. June 2,2003 at 121.
12. Prior to operating on Ms. Perkins, Dr. Metzger had treatednumerous chronic pelvic pain patients who had laparoscopic herniarepairs, utilizing surgical tacks used as a fixation device. With each ofher patients, Dr. Metzger conducted a standardized physical exam,evaluated the patient's medical history, and eliminated potential sourcesfor the post-operative pain at the location of the tacks. Prior totreating Ms. Perkins, Dr. Metzger had had substantial success inrelieving her patients' post-hernia-operation pain by removing thetacks.
13. Dr. Metzger was Ms. Perkins treating physician until late 1998,when Dr. Metzger relocated to California.
14. Prior to the Tacker, Dr. Metzger used a conventional stapler toaffix mesh when repairing hernias. The parties agree that, because thestapler requires a larger trocar site, 10-12 mm with the stapler ascompared to 5mm with the Tacker, there is a greater risk of trauma to thesurrounding tissues, increased complications, and a protracted recoverytime. Accordingly, Dr. Metzger switched to using tacks instead ofstaples.
15. In her Study, Dr. Metzger states that 25 patients had the gortexmesh affixed with the tacks. The court attributes no weight to thisdiscrepancy.
16. In Daubert, the Supreme Court rejected the traditional Frye rule(which had required that a scientific theory be generally accepted by thescientific community to be admissible, see Frye v. United States,293 F. 1013, 1014 (D.C. Cir. 1923)), concluding that adherence to Frye's"rigid `general acceptance' requirement would be at odds with the`liberal thrust' of the Federal Rules [of Evidence]." Daubert, 509 U.S.at 588 (citations omitted).
17. Courts both before and after Daubert have found other factorsrelevant when determining whether expert testimony is sufficientlyreliable to be considered by the trier of fact, see, e.g., AdvisoryCommittee Notes, 2000 Amendments, Fed.R.Evid. 702 (collecting cases),such as whether the theory or method offered by the expert has been putto any non-judicial use, see Cabrera v. Cordis Corp., 134 F.3d 1418,1420-21 (9th Cir. 1998); In re Paoli R.R. Yard PCS Litig., 35 F.3d at 742n.8 (3d Cir. 1994), "or whether [the experts] have developed theiropinions expressly for the purpose of testifying." Daubert v. Merrell DowPhams., Inc., 43 F.3d 1311, 1317 (9th Cir. 1995) ("Daubert II").Moreover, additional factors may be appropriate in a given case, and adistrict court enjoys the same "broad latitude" in deciding what are the"reasonable measures of reliability in a particular case" as it does inreaching its ultimate determination of reliability. Kumho Tire, 526 U.S.at 142, 153.
18. It is worth noting, as an initial matter, that Dr. Metzger couldtestify as a fact witness to her conclusion that the Tacker caused Ms.Perkins' pain. A treating physician can testify as a fact witness aboutthe care and diagnosis rendered as part of a plaintiff's treatment.Santoro, 2002 WL 31059292, at *4. Dr. Metzger reached heropinion/diagnosis that the surgical tacks caused Ms. Perkins' pain as aresult of her treatment of the plaintiff, and then relied on thatopinion/diagnosis when prescribing the further course of medicaltreatment. These circumstances dramatically limit concerns about therelevance and reliability of Dr. Metzger's opinion/diagnosis and thus theadmissibility of the testimony under Daubert. As gatekeeper, the courtmust "make certain that an expert, whether basing testimony uponprofessional studies or personal experience, employs in the courtroom thesame level of intellectual rigor that characterizes the practice of anexpert in the relevant field." Kumho Tire, 526 U.S. at 152. Here, Dr.Metzger brings to the courtroom not merely the "same level ofintellectual rigor" she employs in her medical practice, she bringsopinions that constitute her actual diagnosis of Ms. Perkins, rendered inthe course of her medical practice. Unlike a treating physician who isasked at trial to give an opinion beyond the scope of her diagnosis, Dr.Metzger will merely testify about a diagnosis already given during thecourse of Ms. Perkins' treatment.
19. Among her notable credentials, Dr. Metzger: is the founding memberand past president of the International Pelvic Pain Society; has been thecourse director for a OB/GYN course for the American Association ofGynecological Laparoscopists; has been the Chairman of the Committee forPelvic Pain for the Society for Laparoscopic Surgeons; has held facultypositions at the University of Connecticut, Yale University, and StanfordUniversity; and has submitted numerous articles and papers for peerreview publications. In fact, Dr. Metzger was an editor of the first bookon chronic pelvic pain, Chronic Pelvic Pain: An Integrated Approach(1998). Dr. Metzger is currently an Associate Clinical Professor ofOB/GYN at Stanford University, and frequently lectures on chronic pelvicpain at medical seminars.
20. At his deposition Dr. Luciano testified, in relevant part, asfollows: ATTY WILLCUTTS: As you sit here today, do you have an opinion as to the cause of Ms. Perkins' pelvic pain? DR. LUCIANO: Well, it certainly wasn't related to any gynecologic diseases that she had. I don't believe that the adhesions that she had and the endometriosis she might have had, which was not confirmed, contributed to that. Why? Becayse the multiple laparoscopic procedures that she had by gynecologists, including myself, never really relieved her of her symptoms. That is the reason why I asked for help of another specialist who may look more deeply in non-gynecologic areas, which they did. So it is really a diagnosis of exclusion from my perspective; i.e., I excluded I believe, pelvic, significant pelvic pathology, and the general surgeon, Dr. Donahue, seemed to focus on the source, as he treated the source, the pain got better . . . ATTY WILLCUTTS: Can you say within a reasonable degree of medical certainty, and by that I mean more probable than not, what caused Ms. Perkins' pain? DR. LUCIANO: I believe that the staples or the tacks certainly might have contributed to her groin pain, since it seemed to be so well localized and it appears that once the tack was removed, the pain improved. That is most probably the cause . . .Luciano Dep. Nov. 13, 2000 at 40-41.
21. In his deposition, Dr. Donahue testified that post-operative painis a "known complication of hernia repair surgery" in which tacks areused. Donahue Dep. Dec. 22, 2000 at 65. Dr. Donahue testified that"[t]acks could cause pain by irritating or injuring a nerve, primarily."Id. at 71. Dr. Donahue also wrote a letter to Attorney Willcutts statingin pertinent part: "Ms. Perkins did well from this [tack removal] surgeryI performed on her on 02/07/00. I found two tacks which I believe are thelast two tacks in her. From what I understand, she had had relief of thepain since that time. Given the history of her pain, the fact the she hassignificantly improved after removal of the tacks, and Dr. Metzger'sletter on the subject, I think it is safe to say that Ms. Perkins'symptoms were being caused by the Origin tacks." See PL Brief dated June1, 2003 Brief, Ex. D.
22. Origin claims that "Dr. Metzger has taken her position in spite ofthe following facts: (1) She cannot identify with a reasonable degree ofmedical certainty the mechanism by which tacks cause pain in a woman withchronic pelvic pain; (2) in her first procedure in November 1996 toremove tacks from the Plaintiff she admits she concentrated on removingall offending tacks and in fact removed seven, but that plaintiffs painpersisted; (3) during her treatment of plaintiff, apart from the tacks,she variously identified the Plaintiffs pain as stemming from herovaries, urinary tract infections, pelvic congestion, plaintiff'smenstrual cycle, possible endometriosis, breakthrough bleeding, and, ofcourse, hernias; (4) a second procedure was performed to remove tacks inDecember 1997, but the plaintiff's pain persisted; (5) a third procedurewas performed by Dr. Metzger to remove more tacks in August 1998, butstill the plaintiff's pain continued." See Def. Brief dated June 18,2003.