Nonoperative treatment for lumbosacral radiculopathy: what factors predict treatment failure?

BACKGROUND: Prior studies of nonoperative treatment for lumbosacral radiculopathy have identified potential predictors of treatment failure, defined by persistent pain, persistent disability, lack of recovery, or subsequent surgery. However, few predictors have been replicated, with the exception of higher leg pain intensity, as a predictor of subsequent surgery. QUESTIONS/PURPOSES: We asked two research questions: (1) Does higher baseline leg pain intensity predict subsequent lumbar surgery? (2) Can other previously identified "candidate" predictors of nonoperative treatment failure be replicated?
METHODS: Between January 2008 and March 2009, 154 participants with acute lumbosacral radicular pain were enrolled in a prospective database; 128 participants (83%) received nonoperative treatment and 26 (17%) received surgery over 2-year followup. Ninety-four nonoperative participants (73%) responded to followup questionnaires. We examined associations between previously identified "candidate" predictors and treatment failure defined as (1) subsequent surgery; (2) persistent leg pain on a visual analog scale; (3) persistent disability on the Oswestry Disability Index; or (4) participant-reported lack of recovery over 2-year followup. Confounding variables including sociodemographics, clinical factors, and imaging characteristics were evaluated using an exploratory bivariate analysis followed by a multivariate analysis.
RESULTS: With the numbers available, higher baseline leg pain intensity was not an independent predictor of subsequent surgery (adjusted odds ratio [aOR], 1.22 per point of baseline leg pain; 95% confidence interval [CI], 0.98-1.53; p = 0.08). Prior low back pain (aOR, 4.79; 95% CI, 1.01-22.7; p = 0.05) and a positive straight leg raise test (aOR, 4.38; 95% CI, 1.60-11.9; p = 0.004) predicted subsequent surgery. Workers compensation claims predicted persistent leg pain (aOR, 9.04; 95% CI, 1.01-81; p = 0.05) and disability (aOR, 5.99; 95% CI, 1.09-32.7; p = 0.04). Female sex predicted persistent disability (aOR, 3.16; 95% CI, 1.03-9.69; p = 0.05) and perceived lack of recovery (aOR, 2.44; 95% CI, 1.02-5.84; p = 0.05).
CONCLUSIONS: Higher baseline leg pain intensity was not confirmed as a predictor of subsequent surgery. However, the directionality of the association seen was consistent with prior reports, suggesting Type II error as a possible explanation; larger studies are needed to further examine this relationship. Clinicians should be aware of potential factors that may predict nonoperative treatment failure, including prior low back pain or a positive straight leg raise test as predictors of subsequent surgery, workers compensation claims as predictors of persistent leg pain and disability, and female sex as a predictor of persistent disability and lack of recovery. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.