Introduction The last 2 decades have seen an increased interest in the relationships between medical conditions and medication use and motor vehicle injuries (MVIs). The objective of this study is to examine the effects of various medical conditions and medications used to treat the conditions on subsequent MVIs.

Method The National Population Health Survey is a large nationally representative sample of Canadians who have been surveyed every 2 years since 1994. Self-reported medical conditions and medication use were examined in relation to MVIs reported in the subsequent wave of the survey. Respondents were queried on whether they had any of the following long-term conditions: asthma, arthritis/rheumatism, back problems, high blood pressure, migraine headaches, pain, diabetes and heart disease; measures of distress and depression were also included. They were also asked whether they had taken medications to treat these conditions. Medical conditions and medications were subjected to regression analyses where medical conditions and medications served as controls for each other.

Results The results found that asthma, back problems, migraine and distress showed statistically significant increased risk of subsequent MVIs. Various medications (asthma medication, Demerol, codeine, pain medication and, sleeping medication) were also associated with increased risk of subsequent MVIs. Finally, for some medical conditions, medications have a protective effect while for other conditions, medications have independent effects on the risk of subsequent MVIs.

Conclusion This study suggests that the relationship between medical conditions and medications is complex and in need of further study.