Study design: Merged data from two primary care prospective cohort studies.
Objective: To compare the clinical course of low back pain (LBP) consulters to primary care with and without self-reported referred leg pain.
Summary of background data: In patients with LBP, the presence of leg pain/sciatica is considered a poor prognostic indicator, associated with more severe pain, disability, and time off work. However, questions remain about how best to identify sciatica in primary care and whether self-reported referred leg pain provides a distinct classification for primary care.
Methods: Data from two large prospective cohort studies of consecutive patients consulting with LBP in 13 general practices were merged. Using self-report data patients were divided into three subgroups: (1) those with LBP alone, (2) LBP with referred pain above the knee (LBP + above-knee), and (3) LBP with referred pain below the knee (LBP + below-knee). Unadjusted and adjusted baseline and 6-month follow-up scores on physical, psychological, and social indicators were compared between the groups using multiple regression analysis.
Results: Among 1247 consulters the baseline prevalence of cases with LBP alone was 465 (37%), LBP + above-knee was 308 (25%), and LBP + below-knee was 474 (38%). Baseline severity and 6-month outcomes in the consulters with referred leg pain were significantly worse compared to those with LBP alone across a wide range of clinical characteristics, although differences diminished after adjusting for baseline characteristics.
Conclusion: The clinical course for LBP with self-reported referred leg pain is much worse. However, the fact that differences in outcome were not worse after adjustment suggests that baseline differences in severity and duration of back pain, demographic, and psychological characteristics largely explain the poorer outcomes in patients with referred leg pain. Future research needs to establish if similar results are observed among patients with clinically determined sciatica.