Trajectories of sickness absence and disability pension before and after opioid initiation for noncancer pain: a 10-year population-based study

Chronic noncancer pain is a leading cause of sickness absence (SA) and disability pension (DP). The objectives of this study were to identify trajectories of SA/DP before and after strong and weak opioid initiation for noncancer pain and the factors associated with these trajectories. A longitudinal population-based study of 201,641 people (24-59 years) without cancer who initiated opioid analgesics in 2009 in Sweden was conducted. Trajectories of net annual SA/DP days in the 5 years before/after opioid initiation were estimated with group-based trajectory modelling. Multinomial logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for factors associated with trajectory groups. Among the 6.9% of people initiating strong opioids, 12.5% had persistent high SA/DP (estimated 320 days/year) before and after opioid initiation and 72.9% had persistent low/minimum SA/DP (estimated 30 days/year). Approximately 8.6% of people had increasing SA/DP, and 6.1% had decreasing SA/DP after opioid initiation, although this seemed to reflect continuation of preinitiation patterns. Trajectories were similar at lower SA/DP days/year among those initiating weak opioids. Persistent high SA/DP among strong opioid initiators were associated with ≥5 comorbidities (OR = 8.72, 95% CI 5.61-13.56), ≤9 years of education (OR = 5.83, 95% CI 4.84-7.03), and previous use of antidepressants (OR = 4.57, 95% CI 3.89-5.37) and antipsychotics (OR = 4.49, 95% CI 2.93-6.88). Three-quarters of people initiating opioids for noncancer pain had persistent low/minimum levels of SA/DP 5 years before and after initiation. Increasing and decreasing SA/DP after opioid initiation seemed to reflect a continuation of preinitiation patterns. Our findings highlight the complex range of sociodemographic and medication-related factors associated with persistent SA/DP.