Predicting the Transition to Chronic Pain 6 Months After an Emergency Department Visit for Acute Pain: A Prospective Cohort Study.

Background: Acute pain can transition to chronic pain, a potentially debilitating illness.

Objective: We determined how often acute pain transitions to chronic pain among patients in the emergency department (ED) and whether persistent pain 1 week after the ED visit was associated with chronic pain.

Methods: An observational cohort study conducted in two EDs. We included adults with acute pain (≤10 days) if an oral opioid was prescribed. Exclusion criteria were recent opioid use and use of any analgesics regularly prior to onset of the pain. Research associates interviewed patients during the ED visit and 1 week and 6 months later. The primary outcome, chronic pain, was defined as pain on > 50% of days since ED discharge. We constructed logistic regression models to evaluate the association between persistent pain 1 week after an ED visit and chronic pain, while adjusting for demographic and treatment variables.

Results: During a 9-month period, we approached 733 patients for participation and enrolled 484; 450 of 484 (93%) provided 1-week outcomes data and 410 of 484 (85%) provided 6-month outcomes data. One week after the ED visit, 348 of 453 (77%; 95% confidence interval [CI] 73-80%) patients reported pain in the affected area. New-onset chronic pain at 6 months was reported by 110 of 408 (27%; 95% CI 23-31%) patients. Presence of pain 1 week after ED visit was associated with chronic pain (odds ratio 3.6; 95% CI 1.6-8.5).

Conclusions: About one-quarter of ED patients with acute pain transition to chronic pain within 6 months. Persistence of pain 1 week after the ED visit can identify patients at risk of transition.