Study design: Observational cohort.
Objectives: To describe changes in STarT Back Tool (SBT) categorization following 4 weeks of outpatient physical therapy and to evaluate predictive capabilities of SBT categorization when administered at multiple time points.
Background: Initial assessment information is commonly used to predict long-term outcomes but does not account for changes that occur following initiation of treatment. Changes in SBT categorization during the course of treatment have potential to provide additional prognostic information that could positively impact management of low back pain.
Methods: Patients (n = 123) receiving nonstandardized physical therapy care for low back pain were administered the SBT at intake and 4 weeks later to evaluate SBT changes, which were described as improved (SBT categorization changed from medium to low, high to low, or high to medium risk), stable (SBT categorization remained low or medium risk), or worsened (SBT categorization changed from low to medium, low to high, medium to high, or remained high risk). Clinical outcomes consisted of pain intensity and self-reported disability. Relative contributions of SBT categorization (at intake and 4 weeks) and SBT change patterns as predictors of 6-month clinical outcomes were assessed using separate multiple-regression models, while controlling for other prognostic variables.
Results: Most patients (81.8%) initially categorized as SBT high risk were categorized differently by the SBT at 4 weeks. Eleven percent of patients were described as worsened, based on SBT-category change patterns at 4 weeks. Prediction of 6-month disability scores was improved when considering intake, 4-week, or 4-week change for SBT categorization, with SBT high risk consistently providing unique contributions.
Conclusion: Repeated SBT assessment during the episode of physical therapy has potential to provide additional information for prediction of disability at 6 months. Future studies should investigate optimal management strategies for patients who have worsened SBT risk following physical therapy intervention.
Level of evidence: Prognosis, level 2b.
Keywords: low back pain; prognosis; treatment monitoring.