The responsiveness and minimal important change of the Persian STarT Back Screening Tool in patients with non-specific low back pain.

Background: The Subgroups for Targeted Treatment Back Screening Tool (SBST) is used to assess risk factors for chronic disability in non-specific low back pain (NSLBP). Patients are categorized into three subgroups (low, medium, and high risk) based on their SBST score.

Objectives: To evaluate the responsiveness and minimal important change (MIC) of Persian SBST in NSLBP.

Methods: Responsiveness of SBST over 4 weeks' physiotherapy was investigated (in all the patients, low-, medium-, and high-risk subgroups) by calculating the effect size (ES) of SBST change, correlation with a global rating of change, Roland-Morris Disability Questionnaire and Oswestry Disability Index changes, and receiver operating characteristics (ROC) curve analysis. Five priori hypotheses were formulated about the ES, correlation coefficients, and Area Under the ROC Curve. If 75% or more of the hypotheses were supported, the responsiveness of SBST was approved. The MIC of SBST was determined through coordinates of the ROC curve and Youden index.

Results: All (100%) of the hypotheses were accepted in all patients (200 patients). 40%, 80%, and all (100%) of the hypotheses were accepted in the low-, medium-, and high-risk subgroups, respectively. The MIC values of SBST in all patients, low-, medium-, and high-risk subgroups were 1.5, 0.5, 1.5, and 4.5 points, respectively.

Conclusion: The SBST accurately detects clinical changes when considering all the patients together. The SBST is responsive in the medium- and high-risk subgroups but not in the low-risk subgroup. A reduction of at least 1.5 points in the SBST score is required for clinically meaningful changes.