Efficacy of analgesics in chronic pain: a series of N-of-1 studies.

Abstract

Rational drug treatment of chronic musculoskeletal pain remains a challenge. Although commonly prescribed, the true efficacy of opioid analgesics or of nonsteroidal antiinflammatory drugs remains to be established. Using an N-of 1 design, eight patients with regional cervicobrachial pain received ibuprofen 800 mg/day, codeine 120 mg/day, or placebo during six 2 week periods. Clinical outcomes were assessed by pain diary, VAS of pain and change in pain, and uptime/downtime estimates. In none of the five subjects who completed the 12-week trial was analgesic efficacy of either drug shown. Major psychosocial and other medical influences on the subjects' status were encountered. The N-of 1 methodology is appropriated for evaluating true efficacy of pharmacotherapy in patients with regional musculoskeletal pain.