A research report from Norway published in the December 11, 2011 issue of Addiction found that men taking methadone for opioid addiction were more than twice as likely as the general population to be involved in motor vehicle accidents with personal injury. However, there was no evidence that the methadone itself caused the accidents. The study did not even suggest that stable patients on methadone maintenance treatment (MMT)—men or women—
are any more likely to be in motor vehicle accidents than non-MMT patients.
The lead author told Reuters Health, which picked up the study and ran it under a distorted headline (“Drivers on methadone twice as likely to crash”) December 30, that to blame methadone for the crashes would be speculation. “Many different things go into increasing traffic accident risk, like reduced attention, slowed reaction, slowed psychomotor performance, less accurate psychomotor performance, etc.,” said Jorgen G. Bramness, MD, PhD, of the Norwegian Centre for Addiction Research at the University of Oslo.
The Reuters Health article, mainly because of the misleading headline, attracted a lot of attention among opioid treatment programs (OTPs) in the U.S.
The Study
The study was based on records of all Norwegian adults aged 18 to 70, whose prescription data and motor vehicle histories were followed for 2.5 years. Of the 8.1 million “person years” of data generated, 4,626 “person years” involved all methadone prescriptions for the treatment of opioid addiction, and all benzodiazepine prescriptions. About 1,800 people were prescribed methadone, and 26 motor vehicle accidents were reported in this group. Men who were in MMT were twice as likely to be involved in motor vehicle accidents as the rest of the population. This increased risk couldn’t be explained by exposure to benzodiazepines. The authors stated: “We did not know if the methadone was actually taken, or, if it was taken, when and how much.”
Also:
- Women on MMT were not at increased risk.
- The study did not look at alcohol or drugs other than methadone and benzodiazepines.
- The study did not look at whether the methadone patients were in the induction phase of treatment or were stabilized on methadone.
Conclusions
What does this study mean for OTPs? Not much at all. First, the number of accidents in the methadone group—26—was very small. Second, nothing in the report points to any issues related to the ability of stable MMT patients to drive safely. The fact that methadone had no effect on the accident rate among women in the study suggests that a factor other than the medication may have been involved, the authors said.
When patients are not stabilized on their methadone dose, it is inadvisable for them to drive. When they are stable, they can drive, as Norway’s own regulations say.
For an abstract of the Addiction article, go to
http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2011.03745.x/abstract;jsessionid=79474E85DA1DE24B4C5F7C893A20F158.d01t01. Accessed February 20, 2012.
For the Reuters Health article, go to
http://www.reuters.com/article/2011/12/30/us-drivers-methadone-idUSTRE7BT0Z920111230. Accessed February 20, 2012.
For the Legal Action Center’s 2000 memorandum on methadone and driving, go to
http://www.lac.org/doc_library/lac/publications/mmt-memo_on_driving_and_psychomotor_studies.pdf. Accessed February 20, 2012.
