The patient claimed an interaction with psychiatric medications caused her oral contraceptive to fail.

After 10 years of solo practice as a family physician, Dr. T, age 42, considered himself equipped to handle almost any clinical situation. He also recognized the value of appropriate referrals, but collaborating with a psychiatrist brought a malpractice suit when the patient got pregnant because, she alleged, of the interaction of two drugs.

The 32-year-old woman suffered from bipolar disorder and depression, which she claimed were exacerbated by a divorce and the difficulties she experienced raising her young son, who had developmental problems. Dr. T referred her to a psychiatric clinic under the care of Dr. V. The psychiatrist started her on bupropion (Wellbutrin) for depression and the anticonvulsant carbamazepine (Tegretol) for her bipolar disorder. Later testimony established this as an off-label use of carbamazepine.

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After her discharge from the clinic, the patient continued to see Dr. T. She told him she was “in a relationship” and was taking norethindrone and ethinyl estradiol (Norinyl 1/35) for contraception. Several months later, she announced that she was pregnant despite the oral contraceptive (OC) and had been advised there was a chance of birth defects because she was taking carbamaz-epine during the first trimester.

The woman decided to have an abortion. During counseling at an abortion clinic, she was told that carbamazepine could interfere with the contraceptive effectiveness of norethindrone and ethinyl estradiol. A plaintiff’s expert later explained that carbamazepine could induce liver enzymes that metabolize estrogen, further reducing the efficacy of the hormone, which is already at a low dose in Norinyl 1/35.

After her abortion, the patient consulted a plaintiff’s lawyer. She charged that Drs. T and V caused her to become pregnant by failing to warn her that carbamazepine could interfere with the metabolism of the estrogen in her OC. Dr. T was included in the suit because he had once renewed the carbamazepine prescription while the psychiatrist was away. Served with notice of the lawsuit at the end of a very long week, a distraught Dr. T considered giving up medicine and changing careers.

He did not quit, however, even though the lawsuit lasted almost two years. During the paper discovery phase, charts and other documents were exchanged, including drug information about carbamazepine. Although one research paper discussed its induction of liver enzymes, none of the standard texts mentioned this alleged effect. Dr. T was unaware of it, and the Physicians’ Desk Reference, his standard resource, did not mention a pregnancy risk for patients taking carbamazepine and low-dose OCs at the same time.

Dr. T felt that the plaintiff’s case was shaky, and he urged his attorney to petition the court for dismissal. The plaintiff’s lawyer rushed to enlist his expert witnesses for the dismissal hearing, when they would testify that the medical theory on which the case was based was “accepted by the medical community.”

At the hearing, the patient swore that she had not forgotten to take her birth-control pills and that she did not have GI problems which might have interfered with the absorption of the norethindrone and ethinyl estradiol.

The first plaintiff’s expert was a pharmacist, who said a review of the literature found that carbamazepine promoted induction of liver enzymes. This “more likely than not” was why the OC failed, he testified.

He was followed by an ob/gyn who said that it was “widely accepted in the medical community” that carbamazepine interfered with OCs. Since the patient had testified that she took the norethindrone and ethinyl estradiol every day and other causes had been eliminated, the carbamazepine was the most likely cause of her unplanned pregnancy, he said.

Dr. T listened to this testimony, shaking his head and muttering the whole time. He had never heard of this theory of “anticontraception” that the plaintiff’s experts claimed was so “widely accepted,” nor had any of the colleagues he canvassed.

The judge ruled that he could not dismiss the case because “disputed matters of fact” raised questions for the jury to decide. The case proceeded through the depositions and other discovery, then settled for $135,000 a month before trial.

Legal theory

A trial judge will occasionally dismiss a medical malpractice case but only on limited grounds, such as “failure to state a case” or failure to file papers on time. In this case, Dr. T felt that the medical theory upon which the case was based was faulty, and he encouraged the defense lawyer to challenge it through a motion to dismiss.

Judges decide questions of law. This judge, however, ruled that the controversy was a disputed question of fact, which only a jury can decide, and allowed the case to proceed. Rather than go through the long and expensive process of finding an expert to counter the plaintiff’s, the defense settled.

A more common method of applying for dismissal is to ask the judge to examine the expert witnesses and the scientific theories upon which their testimony is based. The judge then rules on whether the expert opinions are legally admissible. Under the Daubert v. Merrell Dow Pharmaceuticals ruling by the U.S. Supreme Court in 1993, judges have the right and the duty to examine the experts testifying in their courtroom and rule on whether their testimony is based on junk science or “generally accepted scientific principles.”

Dubious theories were once introduced freely before a jury by their lawyer-proponents and allowed to pass unchecked by judges, leading to some strange results in medical malpractice and other technical cases. Under Daubert, the judge must act as a “gatekeeper” to ensure that the expert is qualified and his testimony is “reliable science.” Clinician-defendants may not always get the result they want, but at least they’re entitled to have a judge hear them out.

Protecting yourself

Clinicians can be effective resources in their own defense, but they often neglect to take the initiative.

In this case, Dr. T felt that the experts presented by the plaintiff’s lawyer were unreliable and that the testimony which they presented was not based on accepted medical knowledge. To confirm this view, he canvassed his medical colleagues and proved to his own satisfaction that the plaintiff’s theory of enzyme induction was not commonly accepted in the medical community.

His next step might have been to help the defense lawyer find a credible expert witness to express this point of view effectively. Unfortunately, because of the nature of modern litigation, experts have to be entertainers as well as academically qualified. This narrows the field and makes successful experts expensive and hard to find.