Medicolegal Issues

Inadequate INR Monitoring in Woman Taking Warfarin

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A substantial verdict is returned when inconsistent INR monitoring results in a patient's death.


In July 2009, a 59-year-old California woman was diagnosed with atrial fibrillation and congestive heart failure. She was seen by the on-call cardiologist, who prescribed warfarin but discontinued it after a few days.

The patient then underwent heart surgery and was placed on warfarin again to prevent potential clotting associated with a mechanical heart valve. While in the hospital, the patient underwent daily international normalized ratio (INR) testing, resulting in several discontinuations of warfarin therapy. At the time of discharge, the patient's INR was measured at 2.2—below the patient's therapeutic range. As a result, she was given a new prescription for warfarin (2 mg/d).

At the patient's follow-up office appointment, the cardiologist checked her INR level, which was 3.1. Eight days later, the patient was seen in the office again, and a call was made to the cardiologist six days after that visit, but no further blood tests were performed.

Eight days after the call, the woman was found unresponsive, with evidence of gastrointestinal bleeding. She was taken to an emergency department, where her INR level was at least 24.4—the highest level it was possible for the equipment to measure. The patient also had evidence of bleeding in the lungs and other areas. She died early the following morning.

The plaintiff claimed that the defendants (ie, the defendant cardiologist and his practice group) failed to monitor the decedent's INR properly, although the defendant cardiologist knew the importance of monitoring the INR in a patient using warfarin.

The defendant claimed that the INR level taken after the decedent's hospital stay was within normal range and that monitoring performed at the hospital and at his office was appropriate in frequency. The defendant also claimed that the decedent's death was the result of sepsis, not exsanguination.

According to a published account, a verdict of $1,136,648 was returned. After adjustment according to California's Medical Injury Compensation Reform Act, the total recovery was $386,648.

From the facts given, we know that the patient had unstable warfarin levels postoperatively, requiring that the dose be withheld "several times" during her hospitalization.

Eight days after discharge, the cardiologist saw the patient. Fourteen days later, the patient bled fatally with an INR of 24.4. Thus, it is apparent that the INR was not checked for 22 days following the patient's discharge.

Given the fact that warfarin had to be stopped several times during the patient's hospitalization—and the probability that she had a new target INR, following valve replacement with a mechanical valve—most jurors would have little difficulty concluding that the standard of care was breached.

It is unclear whether the cardiologist or perhaps the patient's primary care provider was to follow her INR postdischarge. That was the causative problem: uncertainty over whose responsibility it was to perform this important monitoring.

While drawing analogies between sports and medicine is often unsuitable, a baseball analogy serves well. A pop fly is hit to deep outfield between two outfielders. Each could easily catch the ball, yet each thinks the other will act. Neither one acts, so the ball drops between the two players, and the team, charged with an error, faces possible loss of the game.

Many malpractice cases involve such a "pop fly" misjudgment: Clinicians fail to act on the mistaken belief that another will. The consequence of an easily handled matter is error and perhaps death.

This problem can be prevented. Within your referral network, establish clear guidelines to determine which clinician is responsible for surveillance, monitoring, and maintenance for any given condition. In the absence of a clear, mutually understood plan, each clinician should take the initiative to manage the patient or conclusively establish who will. This understanding should be shared with the patient and communicated in the record. Many lives may be saved if the responsibilities among clinicians are clear. —DML

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