Prevalence of subtypes of low back pain in a defined population.

Background: For two generations, some back care specialists have emphasized that clinical low back pain is composed of a number of specific syndromes, such as sacroiliitis or trigger points, but the prevalence of these syndromes outside of specialized clinics remains unknown. The purpose of this study was to describe the prevalence of subtypes of low back pain in a defined population.

Methods: The setting was a group model HMO with a population of 54,000. We used a formal group process involving clinicians from many disciplines, long interviews, critical appraisal of the literature, case discussions, and clinical audits to define a set of subtypes of low back pain. Trained physical therapists assessed subtypes in all patients referred for low back pain over a 9-month period, from July 1992 to April 1993.

Results: Of the 213 patients evaluated for low back pain, 72% had acute pain (< 3 months) and only 15% had work-related injury. After classification into subtypes, 32% had acute low back strain, 28% had radicular syndromes, 14% had chronic back strain, 10% had sacroiliac syndromes, 6% had posterior facet syndrome, and the remaining 10% included 12 different syndromes. Only about 10% had more than one clinical syndrome.

Conclusions: A limited number of subtypes of low back pain make up the vast majority of low back pain seen in the population at large. Attention to subtypes may provide a way to improve primary care management of low back pain.