Background: Low back pain (LBP) patients with related leg pain and signs of nerve root involvement are considered to have a worse prognosis than patients with LBP alone. However, it is unclear whether leg pain location above or below the knee and the presence of neurological signs are important in primary care patients. The objectives of this study were to explore whether the four Quebec Task Force categories (QTFC) based on the location of pain and on neurological signs have different characteristics at the time of care seeking, whether these QTFC are associated with outcome, and if so whether there is an obvious ranking of the four QTFC on the severity of outcomes.
Method: Adult patients seeking care for LBP in chiropractic or general practice were classified into the four QTFC based on self-reported information and clinical findings. Analyses were performed to test the associations between the QTFC and baseline characteristics as well as the outcomes global perceived effect and activity limitation after 2 weeks, 3 months, and 1 year and also 1-year trajectories of LBP intensity.
Results: The study comprised 1271 patients; 947 from chiropractic practice and 324 from general practice. The QTFC at presentation were statistically significantly associated with most of the baseline characteristics, with activity limitation at all follow-up time points, with global perceived effect at 2 weeks but not 3 months and 1 year, and with trajectories of LBP. Severity of outcomes in the QTFC increased from LBP alone, across LBP with leg pain above the knee and below the knee to LBP with nerve root involvement. However, the variation within the categories was considerable.
Conclusion: The QTFC identify different LBP subgroups at baseline and there is a consistent ranking of the four categories with respect to outcomes. The differences between outcomes appear to be large enough for the QTFC to be useful for clinicians in the communication with patients. However, due to variation of outcomes within each category individuals' outcome cannot be precisely predicted from the QTFC alone. It warrants further investigation to find out if the QTFC can improve existing prediction tools and guide treatment decisions.
Keywords: Classification; Cohort studies; Low back pain; Primary care; Quebec Task Force classification; Radiculopathy; Referred leg pain; Sciatica.