Patients started on long-term prescription opioids have a threefold higher risk of eventually testing positive for hepatitis C, according to the largest-ever study on the subject.

The findings suggest that, although the absolute risk is low, hepatitis C testing for patients on long-term opioid therapy for non-cancer pain may be beneficial, say researchers from the British Columbia Centre for Disease Control in Canada.

Their study was based on the British Columbia Hepatitis Testers Cohort, which covered 95% of hepatitis C testing in the region and was linked to pharmacy dispensing data.

The study population included more than 380,000 participants with a baseline negative test, no history of injecting drug use and who were largely prescription opioid naive.