Kelly on Malpractice

The frequent use of Daubert in federal court as a defensive sword to strike a fatal blow to plaintiff’s claims of medical causation is well documented. There have been disparate rulings concerning the admissibility of medical diagnoses depending on the “liberal” or “conservative” application of Daubert by the district courts. Even when a physician utilizes the differential diagnosis method to determine causation, some district courts have excluded the opinion as speculative. Fortunately, the Sixth Circuit in Best v. Lowe’s Home Centers, Inc., 563 F.3d 171 (6th Cir.2009) has set forth guidelines for the admissibility of medical causation testimony that is a product of the differential diagnosis method. Best deserves a thorough discussion in this newsletter because it provides an outline for successfully maneuvering past a Daubert objection.

The plaintiff, Mr. Best, visited a Lowe’s store intending to purchase chemicals for his swimming pool. He located a product called Aqua EZ Super Clear Clarifier (Aqua EZ). When Best lifted the plastic container from the shelf, an unknown quantity of the contents splashed onto his face and clothing. The container had allegedly been punctured with a knife by the Lowe’s employee who had opened the shipping box. Best went to the emergency room of a hospital for treatment on the day that the spill occurred. Four months later, Best sought care and treatment from Dr. Moreno, an otolaryngologist, for the injuries associated with the incident. Best told Dr. Moreno that the spilled product had a strong odor, and that immediately thereafter he had suffered from irritation and burning of his skin, irritation to his nasal passages and mouth, dizziness, and shortness of breath. Best also reported that he experienced clear drainage from his nose following the spill and that he eventually lost his sense of smell completely. Dr. Moreno was unable to inspect Best’s mucous membranes for physical damage because they are located too far inside the nasal passages to permit visual examination. Dr. Moreno administered to Best the University of Pennsylvania Smell Identification Test (UPSIT), a standardized test of olfactory function. The test involves various sample chemicals, requiring the test subject to choose one of four descriptions of each sample’s scent. Best scored a six on the test, a score consistent with complete anosmia (loss of smell). Dr. Moreno testified in his deposition that loss of smell is caused by either a virus, an accident, tumors to the brain, surgery into the brain, or exposure to chemicals. He also conceded that sometimes anosmia is idiopathic, meaning that it occurs for unknown reasons, and that some medications can cause a loss of the sense of smell.

Best’s attorney obtained a Material Safety Data Sheet (MSDS) prepared by the supplier of the active ingredient in Aqua EZ. Dr. Moreno reviewed the MSDS, which identifies the chemical in Aqua EZ as “hazardous” and states that “prolonged or repeated contact may cause eye and skin irritation.” According to the MSDS, if the chemical is inhaled, the person should be “removed to fresh air, if not breathing give artificial respiration. If breathing is difficult, give oxygen and get immediate medical attention.” The Handling Instructions state: “Do not inhale…. Use only with adequate ventilation.” Dr. Moreno concluded that the inhalation of Aqua EZ has the potential to cause damage to the nasal and sinus mucosa and the nerve endings of the olfactory bulb. Dr. Moreno did not know the precise amount of the offending chemical that Best had been exposed to, nor was he able to determine the threshold level of exposure that could cause harm. Yet, because of the temporal relationship between Best’s exposure to the chemical and the onset of his symptoms, in conjunction with a principled effort to eliminate other possible causes of anosmia, Dr. Moreno formed the opinion that the inhalation of Aqua EZ caused Best to lose his sense of smell.

Best sued and the case was removed to federal court. After Best identified Dr. Moreno as an expert witness, counsel for Lowe’s took the doctor’s deposition. Lowe’s then moved for the exclusion of Dr. Moreno’s testimony regarding the cause of Best’s injury and also moved for summary judgment. The district court excluded Dr. Moreno’s proposed testimony after concluding that the doctor’s opinion was too speculative. The district court found “red flags” that purportedly demonstrated a lack of reliability in Dr. Moreno’s opinion, which were the following: (1) improper extrapolation, (2) reliance on anecdotal evidence, (3) reliance on temporal proximity, (4) insufficient information about the case, (5) failure to consider other possible causes, and (6) lack of testing. The district court also faulted Dr. Moreno for relying on past experiences with patients who had been exposed to different chlorine derivatives and the “temporal proximity between the incident and the reported injury.” The court next criticized Dr. Moreno for having “insufficient information about the case” because he relied on Best’s general and subjective report of the accident, an examination of Best, and the MSDS sheet. The court then noted that Dr. Moreno failed to consider other possible causes. Therefore, the district court excluded Dr. Moreno’s causation testimony as “unscientific speculation.”

On appeal, the Sixth Circuit began its analysis de novo by defining Dr. Moreno’s differential diagnosis as the method by which a physician determines what disease process caused a patient’s symptoms. The physician considers all relevant potential causes of the symptoms and then eliminates alternative causes based on a physical examination, clinical tests, and a thorough case history. The Sixth Court recognized differential diagnosis as “an appropriate method for making a determination of causation for an individual instance of disease. It is a standard scientific technique of identifying the cause of a medical problem by eliminating the likely causes until the most probable one is isolated. The Court carefully pointed out that not every opinion reached via a differential diagnosis will meet the standard of reliability required by Daubert. Therefore, the Sixth Circuit adopted a test for differential diagnoses when tested by a Daubert motion. A medical causation opinion in the form of a doctor’s differential diagnosis is reliable and admissible where the doctor: (1) objectively ascertains, to the extent possible, the nature of the patient’s injury, (2) “rules in” one or more causes of the injury using a valid methodology, and (3) engages in “standard diagnostic techniques by which doctors normally rule out alternative causes” to reach a conclusion as to which cause is most likely.

In connection with the third “rules out” prong, if the doctor “engages in very few standard diagnostic techniques by which doctors normally rule out alternative causes,” the doctor must offer a “good explanation as to why his or her conclusion remains reliable.” Similarly, the doctor must provide a reasonable explanation as to why “he or she has concluded that any alternative cause suggested by the defense was not the sole cause.” The Sixth Circuit reversed the district court, by ruling that Dr. Moreno employed a valid methodology to “rule in” Aqua EZ as a potential cause and engaged in standard techniques to “rule out” alternate causes.

Best v. Lowes Home Centers, Inc. is a watershed case. Every lawyer who handles medical malpractice and personal injury cases in federal court must read it.