Purpose: (1) To analyse the clinical utility of the STarT Back Screening Tool (SBST) in emergency departments by describing changes in classification over time and; (2) to identify what would be the best time to use the SBST to predict long-term clinical outcomes in patients with acute nonspecific low back pain (LBP) seeking emergency care.
Methods: A 6 months prospective inception cohort study was conducted. 200 participants with LBP seeking emergency medical treatment were included. Pain intensity, disability and SBST were collected at baseline, 6 and 26 weeks. Categories of improvement, clinical worsening, and stability were created to calculate the changes in the SBST subgroups. Linear regression models were built to analyse the predictive ability of SBST when applied at baseline, 6 weeks as well as changes in the subgroup from baseline to 6 weeks. These models were adjusted for potential confounders.
Results: 45% of patients were classified as high risk of chronicity at baseline. Most patients classified as medium (86.7%) or high (52.4%) risk changed their risk subgroup after 6 weeks and most of them improved. The SBST improved the prediction for all outcomes when applied at 6 weeks (R2 = 22.1% for disability and R2 = 15.6% for pain intensity), but not at baseline.
Conclusion: Most of patients seeking care in emergency departments with a new episode of acute LBP improved after 6 weeks. The use of SBST to guide initial treatment and to predict clinical outcomes are most indicated when the instrument is applied after 6 weeks after presentation to emergency care. These slides can be retrieved under Electronic Supplementary material.
Keywords: Acute low back pain; Emergency department; Inception cohort; Prediction models; Prognosis; STarT Back Tool.