One-week and 3-month outcomes after an emergency department visit for undifferentiated musculoskeletal low back pain

Study objective: Nearly 3 million patients present to US emergency departments (EDs) annually with undifferentiated musculoskeletal low back pain. Little is known about short- and longer-term outcomes in this group. We seek to describe the pain and functional outcomes 1 week and 3 months after discharge in a sample of ED patients presenting with undifferentiated musculoskeletal low back pain. Methods: We used a prospective observational descriptive cohort design, enrolling ED patients with a chief complaint of low back pain classified as musculoskeletal in origin by the ED attending physician. We defined low back pain as pain originating in the posterior back between the tips of the scapulae and upper buttocks and excluded any patient with a traumatic back injury occurring within the previous month. We interviewed patients in the ED and then by telephone follow-up 1 week and 3 months after ED discharge, using a scripted closed-question data collection instrument. Our primary outcome was functional limitation attributable to low back pain assessed with a validated scale. Secondary outcomes included pain and analgesic use during the 24 hours before each follow-up telephone call. Results: During a 9-month period beginning in July 2009, we approached 894 patients, of whom 556 were enrolled. We obtained follow-up on 97% of our sample at 1 week and 92% at 3 months. One week after ED discharge, 70% (95% confidence interval [CI] 66% to 74%) of patients reported back painrelated functional impairment, 59% (95% CI 55% to 63%) reported moderate or severe low back pain, and 69% (95% CI 65% to 73%) reported analgesic use within the previous 24 hours. Three months after ED discharge, 48% (95% CI 44% to 52%) of patients reported functional impairment, 42% (95% CI 38% to 46%) reported moderate or severe pain, and 46% (95% CI 44% to 50%) reported analgesic use within the previous 24 hours. Conclusion: There is substantial short- and longer-term morbidity and ongoing analgesic use among patients who present to an ED with undifferentiated musculoskeletal low back pain.