PURPOSE: We evaluated whether the rate of incident chronic opioid use is higher in obese patients with rheumatoid arthritis (RA).
METHODS: Participants with RA in Forward were asked about use of weak and strong opioid medications on semi-annual surveys. Incident chronic opioid use was defined as new reported use extending over two contiguous surveys (~7 to 12 months). Cox proportional hazards models evaluated associations between body mass index (BMI) at enrollment and incident chronic opioid use (overall use and strong opioid use). Models adjusted for demographics, smoking, disease duration, RA treatments, household income, and educational level. The predicted 5-year cumulative incidence was calculated from Cox models.
RESULTS: Among 19,794 participants, 2,802 experienced an incident episode of chronic opioid use over 93,254 person-years of follow-up. Higher BMI was associated with higher risk of chronic opioid use. Severe obesity (BMI >35 kg/m2 ) was associated with a higher risk of overall use [HR 1.74 (1.72,2.04) p<0.0001] and strong opioid use [HR 2.11 (1.64,2.71) p<0.001] compared to normal BMI. This association was partially explained by greater comorbidity, pain, and disability in obese groups. The attributable risk for obesity was 15% of overall opioid use and 24% of strong opioid use.
CONCLUSIONS: Obesity is associated with a substantially higher risk of incident chronic opioid use. Approximately 1 in 4 cases of incident use of strong opioids may be attributable to obesity, suggesting a major public health impact. Interventions to prevent or reduce obesity could have an important impact on the use of opioids.