Clinical course and prognostic factors in acute low back pain: an inception cohort study in primary care practice.

OBJECTIVE: To describe the natural course of recent acute low back pain in terms of both morbidity (pain, disability) and absenteeism from work and to evaluate the prognostic factors for these outcomes.

DESIGN: Inception cohort study.

SETTING: Primary care.

PATIENTS: 103 patients with acute localised non-specific back pain lasting less than 72 hours.

MAIN OUTCOME MEASURES: Complete recovery (disappearance of both pain and disability) and return to work.

RESULTS: 90% of patients recovered within two weeks and only two developed chronic low back pain. Only 49 of 100 patients for whom data were available had bed rest and 40% of 75 employed patients lost no time from work. Proportional hazards regression analysis showed that previous chronic episodes of low back pain, initial disability level, initial pain worse when standing, initial pain worse when lying, and compensation status were significantly associated with delayed episode recovery. These factors were also related to absenteeism from work. Absenteeism from work was also influenced by job satisfaction and gender.

CONCLUSIONS: The recovery rate from acute low back pain was much higher than reported in other studies. Those studies, however, did not investigate groups of patients enrolled shortly after the onset of symptoms and often mixed acute low back pain patients with patients with exacerbations of chronic pain or sciatica. Several sociodemographic and clinical factors were of prognostic value in acute low back pain. Factors which influenced the outcome in terms of episode recovery (mainly physical severity factors) were only partly predictive of absenteeism from work. Time off work and return to work depended more on sociodemographic and job related influences.