Analgesic use: A predictor of chronic pain and medication overuse headache - The Head-HUNT Study

Objective: To examine the relation between analgesic use at baseline and the subsequent risk of chronic pain (greater than or equal to15 days/month) and the risk of analgesic overuse. Methods: In total, 32, 067 adults reported the use of analgesics in 1984 to 1986 and at follow-up 11 years later (1995 to 1997). The risk ratios (RR) of chronic pain and RR of analgesic overuse in the different diagnostic groups (i.e., migraine, nonmigrainous headache, neck pain, and low-back pain) were estimated in relation to analgesic consumption at baseline. Results: Individuals who reported use of analgesics daily or weekly at baseline showed significant increased risk for having chronic pain at follow-up. The risk was most evident for chronic migraine (RR = 13.3, 95% CI: 9.3 to 19.1), intermediate for chronic nonmigrainous headaches (RR = 6.2, 95% CI: 5.0 to 7.7), and lowest for chronic neck (RR = 2.4, 95% CI: 2.0 to 2.8) or chronic low-back (RR = 2.3, 95% CI: 2.0 to 2.8) pain. Among subjects with chronic pain associated with analgesic overuse, the RR was 37.6 (95% CI: 21.3 to 66.4) for chronic migraine, 14.4 (95% CI: 10.4 to 19.9) for chronic nonmigrainous headaches, 7.1 for chronic neck pain (95% CI: 5.5 to 9.2), and 6.4 for chronic low-back pain (95% CI: 4.9 to 8.4). The RR for chronic headache (migraine and nonmigrainous headache combined) associated with analgesic overuse was 19.6 (95% CI: 14.8 to 25.9) compared with 3.1 (95% CI: 2.4 to 4.2) for those without overuse. Conclusion: Overuse of analgesics strongly predicts chronic pain and chronic pain associated with analgesic overuse 11 years later, especially among those with chronic migraine.