Change in opioid dose and change in depression in a longitudinal primary care patient cohort

Depression is associated with receipt of higher doses of prescription opioids. It is not known whether the reverse association exists in that an increased opioid dose is associated with increased depression. Questionnaires were administered to 355 patients with chronic low back pain at baseline and 1-year and 2-year follow-up. Depression, pain, anxiety, health-related quality of life, and social support or stresswere obtained by survey. Opioid type and dose and comorbid conditionswere derived fromchart abstraction.Randomintercept, generalized linearmixedmodelswere computed to estimate the association between change in opioidmorphine equivalent dose (MED) thresholds (0, 1-50, >50 mg) and probability of depression over time. Second, we computed the association between change in depression and odds of an increasing ME Dover time. After adjusting for covariates, an increase to>50 mg MED fromnonuse increased a participant's probability of depression over time (odds ratio [OR] = 2.65; 95% confidence interval [CI], 1.17-5.98). An increase to 1 to 50mg MED did not increase an individual's probability of depression over time (OR51.08; 95% CI, 0.65-1.79). In unadjusted analysis, developing depression was associated with a 2.13 (95% CI, 1.36-3.36) increased odds of a higher MED. This association decreased after adjusting for all covariates (OR=1.65; 95%CI, 0.97-2.81). Post hoc analysis revealed that depression was significantly associated with a 10.1-mgMEDincrease in fully adjustedmodels.Change to a higherMEDleads to an increased risk of depression, and developing depression increases the likelihood of a higherMED.We speculate that treating depression or loweringMEDmay mitigate a bidirectional association and ultimately improve pain management.