Pain medication and nerve injuries in upper or lower limb—a Swedish national registry study

Introduction: Severe symptoms and disability may remain after upper and lower limb nerve injuries with an additional risk of persistent pain and consumption of pain medication. Objectives: To examine whether upper and lower limb nerve injuries, potentially causes of pain, are associated with risk of using pain medication. Methods: Drug use at an individual level was analysed in a large Swedish record-linkage database covering 6,579,612 individuals (age ≥18 years; first-ever nonsurgically [n = 5,249] and surgically treated [n = 3,669] upper limb and nonsurgically [n = 1,260] and surgically treated [n = 14] lower limb nerve injuries; International Classification of Diseases, 10th version and NOMESCO codes; 90-day washout period after surgery). Associations were expressed as relative risks (95% confidence interval), unadjusted and adjusted for demographic and socioeconomic factors. Results: Adjusted risk for use of pain medications during the first year after diagnosis and/or surgery was higher in upper (4.85 [4.51-5.23]) and lower (5.60 [4.85-6.48]) limb nerve injuries than in the general population and was considerably lower if surgery was performed (0.31 [0.26-0.36]). Risk during the second year declined but remained. Consumption of pain medication during the first year increased risk of use during the second year (11.45 [11.35-11.56]). Older age, female sex, living alone, low-middle income, and immigrant status were associated with a higher risk. Conclusion: Upper and lower limb nerve injuries substantially increase the risk of long-term use of pain medication. Surgical treatment reduces the risk during the first year, indicating the relevance of appropriate surgical treatment, but demographic and socioeconomic disparities remain essential determinants. Notably, previous consumption during the first year increases the risk of consumption in the second year. Despite being a third-line therapy for neuropathic pain, opioids accounted for many prescriptions.