Initiating disease-modifying anti-rheumatic drugs rapidly reduces purchases of analgesic drugs in juvenile idiopathic arthritis

Objective To describe the use of analgesics 12 months before and after initiation of the first disease-modifying anti-rheumatic drug (DMARD) in children with juvenile idiopathic arthritis (JIA). Method A register-based study linked three nationwide registers in Finland: the Register on Reimbursement for Prescription Medicines, the Drug Purchase Register (both maintained by the Finnish Social Insurance Institution), and the Finnish Population Register. The study ran from 1 January 2010 to 31 December 2014. It included 1481 patients aged < 16 years with diagnosed JIA and 4511 matched controls. Index day was the date when reimbursement for JIA medication was approved and treatment was initiated. The study period included 12 months pre- and post-index date, and purchases of prescription drugs were assessed for 3 month periods. Results Non-steroidal anti-inflammatory drugs (NSAIDs) were purchased for 60% of the patients. Compared to controls, NSAID purchases for JIA patients were at their highest during the last 3 months before the index day [relative rate (RR) 21.2, 95% confidence interval (CI) 17.1-26.2], and they decreased steeply over the 10-12 months post-index (RR 4.0, 95% CI 3.1-5.0). Similar trends were seen with paracetamol and opioid purchases, but only 2% of patients purchased opioids during the 12 months pre-index and 1% during the 12 months post-index. Methotrexate was the most commonly used DMARD (91.9%), biologic DMARDs were used by 2.8% and glucocorticoids by 24.8% in the 3 months after the index day. Conclusion Initiation of DMARDs rapidly reduces the need for analgesics in patients with JIA.