Improving the Predictive Validity of the Dutch STarT Back Tool.

Abstract

The purpose of this study was to evaluate whether the predictive validity of the Dutch version of the STarT Back Tool (SBT) can be improved by (1) using other cut-off values, (2) changing the items, or (3) adding prognostic factors to the SBT. This was a secondary analysis of a prospective cohort study (PRINS study: Prevalence of Risk groups in Neck- and back pain patients according to the STarT back screening tool) in patients with low back or neck pain. The predictive validity was calculated with a relative risk ratio and a Spearman correlation. The new cut-off values were calculated with receiver operating characteristic curves. Replacing items of the SBT and adding new items were assessed with logistic regression analyses. A total of 150 patients were included; 51% were categorized as having low risk, 39% as moderate risk, and 11% as high risk. Changing the cut-off total score to ≤2 and the subscore to ≥5 led to an improvement of the Spearman correlation and RR. Adding the item "duration of the complaints" improved the RR for moderate risk (3.6) (95% CI = 1.6-7.9) and for high risk (9.0) (95% CI = 4.2-19.1) compared with low risk. The new Spearman correlation was improved to rs = 0.37. The predictive validity was improved by adding the item "duration of the complaints" and changing the cut-off values.