Predicting who develops chronic low back pain in primary care: a prospective study.

OBJECTIVES: To quantify the relative contribution of premorbid and episode specific factors in determining the long term persistence of disabling symptoms of low back pain. DESIGN: Prospective cohort study. SETTING: Two general practices in the south Manchester area. PARTICIPANTS: 180 patients, who previously participated in a cross sectional population survey, who consulted because of low back pain during the study period. They were followed at 1 week and 3 and 12 months after consultation. MAIN OUTCOME MEASURE: Persistent disabling low back pain in the 12 months after the consultation. RESULTS: Disabling low back pain persisted in one third of participants after consultation and was more common with increasing age, among those with a history of low back pain, and in women. Persistence of symptoms was associated with "premorbid" factors (high levels of psychological distress (odds ratio 3.3; 95% confidence interval 1.5 to 7.2), poor self rated health (3.6; 1.9 to 6.8), low levels of physical activity (2.8; 1.4 to 5.6), smoking (2. 1; 1.0 to 4.3), dissatisfaction with employment (2.4; 1.3 to 4.5)) and factors related to the episode of low back pain (duration of symptoms, pain radiating to the leg (2.6; 1.3 to 5.1), widespread pain (6.4; 2.7 to 15), and restriction in spinal mobility). A multivariate model based on six factors identified groups whose likelihood of persistent symptoms ranged from 6% to 70%. CONCLUSIONS: The presence of persistent low back pain is determined not only by clinical factors associated with pain but also by the premorbid state.