Abstract
BACKGROUND: The 9-item STarT-Back screening tool was developed in primary care patients with low back pain (LBP) to identify those at greatest risk for chronic pain and requiring targeted treatment. We conducted a secondary data analysis study to examine the performance of comparable questionnaire items in a sample of primary care patients with well-defined acute LBP. METHODS: In a prospective cohort study, 605 primary care patients with LBP of less than 30 days answered a questionnaire with 6 items identical and 3 items analogous to the 9-item STarT-Back. Participants were followed up at 6 months and 2 years. STarT-Back rules were applied to classify participant's risk of chronic LBP, and the performance of the screening items in predicting outcomes was assessed using likelihood ratios. RESULTS: The proportion of patients with chronic pain at follow-up was considerably lower (6 months: 22%; 2 years: 25%) than in the STarT-Back validation cohort (40%) of patients with pain of any duration. The probability of developing chronic pain given a high-risk designation by items similar to the STarT-Back increased the pre-test probability to 31% and 35%. Likelihood ratios were close to 1. CONCLUSIONS: A risk classification schema using the recommended cut-off scores with items similar to the STarT-Back in a primary care population with strictly defined acute LBP had limited ability to identify persons who progressed to chronic pain. The results suggest caution when applying the STarT-Back in patients with acute LBP and a need to consider a modification of its cut-offs.