Antipsychotic Adherence Linked With Lower Car Crash Risk

In drivers with schizophrenia, better adherence to antipsychotic medication is associated with a lower risk for motor vehicle crashes, according to new research.

In a case-crossover study, perfect adherence to antipsychotic medication in drivers with schizophrenia was associated with a 50% reduction in the odds of a crash, relative to complete nonadherence.

Physicians and fitness-to-drive policy makers might consider antipsychotic treatment adherence as a condition for maintaining an active driver’s license in these patients, the authors suggest.

The study was published June 9 in the Canadian Medical Association Journal. 

Driving Safety Data 

“Whether a person is safe to drive is a question that comes up for psychiatrists and physicians like me who look after people when they are in the hospital with a worsening of their schizophrenia,” study author John A. Staples, MD, MPH, clinical associate professor of medicine at the University of British Columbia in Vancouver, told Medscape Medical News.

“This is particularly important for people who have schizophrenia, because we know schizophrenia impairs their judgment. Often, these individuals have had problems with driving in the past,” Staples said.

The investigators examined population-based administrative health and driving data from British Columbia. They included patients with schizophrenia who were involved as drivers in police-attended motor vehicle crashes from 2001 to 2016. Eligible participants filled prescriptions for antipsychotic medication as outpatients in the 2 years before the crash.

“We have data on all their health issues specific to hospital visits with physicians and medication data, and we also have data on their driving, including crashes and traffic accidents. It’s unique that we have both data sets,” Staples noted.

The investigators assessed adherence by looking at how often in the 30 days before their crash these drivers filled prescriptions for their antipsychotic medication. They also examined how often patients filled the prescriptions in a 30-day period 1 year before the crash.

The final sample consisted of 1130 crashes involving 1001 drivers. At the time of the crash, the median age of the drivers was 37 years. Two-thirds of participants were male, 58.1% resided in an urban area, and 84.5% had a driver’s license. More than half (54.8%) also had one or more traffic violations in the past 3 years.

About half (49.8%) of all crashes resulted in an injury, and 0.7% resulted in a fatality. Attending police reported that the driver’s condition was a contributing factor in 43.5% of the crashes.

“We hope these findings encourage people with schizophrenia to take their antipsychotics,” Staples said. The results should also highlight the need for physicians faced with patients who may not be adherent to think about driving safety. “We don’t want there to be a crash where somebody gets hurt, but on the other hand, suspending or canceling somebody’s license is a grave blow to independence and the ability to work. That’s the difficult tradeoff physicians are often left struggling with. We want to make sure we are making decisions that are justified when we take away the freedom of being able to drive,” Staples said.

Valuable Research

Mark Rapoport, MD, professor of psychiatry at the University of Toronto, told Medscape Medical News that physicians treating patients with schizophrenia should stress the importance of adherence and driving safety.

“This is a very good study that shows the positive outcome of staying on medication. But there is variability among individuals, so it is hard to make a sweeping declaration that everyone must be adherent or they can’t drive. To me as a clinician, it comes down to the judgment and insight of the patient. Do they have the wherewithal to realize that they should wait until they take their medication before they get behind the wheel? That they need to take another form of transportation? Some people don’t have the ability to do that,” Rapoport said.

“A study like this can’t answer those nuanced questions, but it is a good study that shows the very positive outcome of staying on medication,” he said.

“Given the elevated crash risk among those with schizophrenia, this research is valuable in that it provides evidence of the efficacy of antipsychotics in improving a person’s safety and well-being as it applies to driving,” Simon B. Sherry, PhD, professor of psychology and neuroscience at Dalhousie University in Halifax, told Medscape Medical News.

“The ability to drive can provide freedom and independence and improve quality of life. Unfortunately, many of the symptoms of schizophrenia, such as disorganized thinking; reduced motivation; trouble with attention, memory, and decision-making; and difficulty with daily activities, can make regularly taking medication more challenging,” Sherry said.

“As a psychologist, I do not prescribe medication, but I can vouch for the efficacy of nonpharmaceutical treatments such as cognitive behavioral therapy for managing symptoms. It would be interesting to see future research comparing whether this therapy is also associated with lower crash risk and whether such treatment is equally effective in reducing crash risk as antipsychotic medications,” he said.

The study was supported by the Canadian Institutes of Health Research. Staples, Rapoport, and Sherry reported having no relevant financial relationships.