Patients on chronic opioids can be safe drivers.

SAN FRANCISCO -- On driving simulators, 51 patients on chronic opioids performed just as well as 49 control subjects, preliminary data from an ongoing study found.

The conventional recommendation that patients taking chronic opioids should avoid driving may not be necessary, Dr. Asokumar Buvanendran and associates stated in a poster presentation at the annual meeting of the American Society of Anesthesiologists.

The randomly selected patients in the opioid group were taking 20-60 mg/day of opioids for chronic pain. They and the age-matched, randomly selected control subjects spent 3 minutes practicing on a driving simulator and then took a 12-minute test on the simulator in a quiet room. The study excluded subjects with any medical condition or other medication regimen that could affect driving skills.

There were no significant differences between groups in measures of attention, reaction time, or number of crashes, reported Dr. Buvanendran, an anesthesiologist at Rush University, Chicago.

Members of both groups veered a mean of 4 feet from the center line during simulated driving (a measure of attention). Even the best drivers had "accidents" because of the demanding structure of the driving course, and each group averaged five crashes per driver. Reaction times were 0.67 seconds in the opioid group and 0.69 seconds in the control group, a difference that was not statistically significant. Results for the two groups were statistically equivalent, separate analyses showed.

Chronic opioid use has increased in the past decade as physicians have become more attuned to the need to treat chronic pain, coinvestigator Jeffrey S. Kroin, Ph.D., said in an interview at the meeting. The doses used by the study patients are higher than starting doses and are more typical of doses taken by patients on opioids for 6 months or longer for problems such as complex regional pain syndrome, said Dr. Kroin, also of the university.

Package labels for opioids caution against driving and many other activities while on the medication, but these restrictions may be "ultraconservative" for patients on chronic therapy once they have adjusted to the drug.

"There may not be any true impairment," Dr. Kroin said. "Realistically, there are people who have been on chronic opioids for 10-20 years and have been driving. What should physicians be telling these people?"

Setting more reasonable restrictions on patients taking chronic opioids could greatly improve their quality of life, coinvestigator Mario Moric, Ph.D., added in an interview.

If they're not allowed to drive, patients have more difficulty taking care of themselves, shopping for groceries, and getting to the clinic if they need help with a problem. These patients tend to get isolated.

"We want to take away a restriction that may not be that critical to their or anybody else's safety," said Dr. Moric, also of the university.

Driving is one of the more complicated tasks that people do on a regular basis, as it requires many different sensory inputs, cognitive skills, and timely reactions. That made it a good task for assessing the functional effects of chronic opioids, he said.

The study is ongoing, with a goal of enrolling hundreds of subjects.

The investigators also are starting a separate study of the effects of anesthesia on driving after ambulatory surgery. Typically, patients are told not to drive for at least 24 hours after ambulatory surgery, even if they feel fine, Dr. Kroin noted.

That restriction is "vestigial, because of the kinds of anesthetics that we used 40-50 years ago. It was true they had a long half-life," but more modern anesthetic agents may not necessitate a 24-hour restriction on driving, he suggested.

BY SHERRY BOSCHERT

San Francisco Bureau