New Opioid Analgesic Use and the Risk of Injurious Single-Vehicle Crashes in Drivers Aged 50–80 Years: A Population-based Matched Case–Control Study

Joel Monárrez-Espino; Lucie Laflamme; Christian Rausch; Berty Elling; Jette Möller


Age Ageing. 2016;45(5):628-634. 

In This Article

Abstract and Introduction


Background: the increasing trend in opioid analgesic use among older drivers has raised concerns about their risk of being involved in car crashes.

Aim: to investigate if older drivers who started using opioid analgesics have a higher probability of being involved in injurious crashes.

Methods: population-based matched case–control study. Data from population registers were merged using a personal identity number. Cases were drivers aged 50–80 years responsible for a single vehicle crash between 01.07.05 and 31.12.09 that led to at least one injured passenger (n = 4,445). Four controls were randomly matched to each case by sex, birth month/year, and residence area from persons holding a valid driving license who did not crash during the study period. New use was defined as at least one dispensation within 1–30 days prior to the crash, but none within the previous 31–180 days; frequent use when ≥3 dispensations were given within 0–180 days, with at least one within 31–180 days. Individuals using 1–2 non-opioid analgesic medications were used as reference category. Conditional logistic regression was used to estimate odds ratios (OR; 95% CI) adjusting for benzodiazepine use, co-morbidity, civil status and occupation.

Results: adjusted odds for new use were two-fold that of drivers using 1–2 non-opioid analgesics medications (2.0; 1.6–2.5). For frequent use, adjusted odds were also increased regardless of number of dispensations (3–4 = 1.7; 1.3–2.1, 5–6 = 1.6; 1.2–2.3, and ≥7 = 1.7; 1.3–2.1).

Conclusion: new, but also frequent opioid analgesic use, resulted in an increased probability of single vehicle crashes. While more epidemiologic evidence is needed, patients could be advised to refrain from driving when using opioid analgesics.


In Sweden, as in many countries, there has been a shift in the age distribution of the population, with an increasing proportion of older people. At present, 19.6% of the inhabitants is aged ≥65 years, but this percentage is expected to reach 25% by 2050.[1] Thus, an increasing number of older adults can now live an independent and active life, which in many settings involves the use of a vehicle as a means of sustained mobility.

However, lower sensory, memory, cognition, attention and other relevant functions required to drive as well as slower physical responses are common in older persons.[2] Also, they usually suffer from chronic medical conditions that may further limit their driving abilities.[3] Such morbidities often require medications, some of which give side effects that can affect driving performance and increase crash risks.[3,4]

The use of opioids under driving conditions has been[5,6] and continues to be[7,8] a subject of debate. While it is known that opioids can affect driving performance due to symptoms arising from their direct effect on the nervous system, some consider them to be relatively safe, at least among chronic users,[5] possibly due to tolerance of the side effects.[7] Some studies even report that relieving pain could actually improve cognitive function[9] and visual and auditory reflexes.[10] However, so far most evidence on the topic is based on cognitive[7,11] and experimental[5,8] or simulation studies[12] conducted in all adults, with a number of them focusing on the treatment of addiction.

The opioid analgesics, commonly used to treat pain and other conditions of older people,[13] is a group of medications where there is limited epidemiological evidence of their effect on the risk of road traffic crashes.

A recent meta-analysis of epidemiologic studies on the role of analgesics and the risk of road traffic crashes in senior drivers[14] revealed a significant increase in the probability of crashing (OR 1.2; 95% CI 1.08–1.32), which could be due to the presence of new opioid analgesic users who have not developed adaptation to the medication.

We aim to investigate this further using national Swedish material focusing on older adult drivers who recently started opioid analgesic treatment and assessed whether they had a higher chance of being involved in single injurious crashes compared with frequent opioid analgesic users and non-users.