Subgrouping low back pain: a comparison of the STarT Back Tool with the Orebro Musculoskeletal Pain Screening Questionnaire.

INTRODUCTION: Clinicians require brief, practical tools to help identify low back pain (LBP) subgroups requiring early, targeted secondary prevention. The STarT Back Tool (SBT) was recently validated to subgroup LBP patients into early treatment pathways.

AIM: To test the SBT's concurrent validity against an existing, popular LBP subgrouping tool, the Orebro Musculoskeletal Pain Screening Questionnaire (OMPSQ), and to compare the clinical characteristics of subgroups identified by each tool.

METHODS: Two hundred and forty-four consecutive 'non-specific' LBP consulters at 8 UK GP practices aged 18-59years were invited to complete a questionnaire. Measures included the OMPSQ and SBT, disability, fear, catastrophising, pain intensity, episode duration and demographics. Instruments were compared using Spearman's correlations, tests for subgroup agreement and discriminant analysis of subgroup characteristics according to reference standards.

RESULTS: Completed SBT (9-items) and OMPSQ (24-items) data was available for 130/244 patients (53%). The correlation of SBT and OMPSQ scores was 'excellent (rs=0.80). Subgroup characteristics were similar across the low, medium and high subgroups, but, the proportions allocated to 'low', 'medium' and 'high' risk groups were different, with fewer patients in the SBT's high risk group. Both instruments similarly discriminated for reference standards such as disability, catastrophising, fear, comorbid pain and time off work. The OMPSQ was better at discriminating pain intensity, while the SBT was better for discriminating bothersomeness of back pain and referred leg pain.

CONCLUSIONS: The SBT baseline psychometrics performed similarly to the OMPSQ, but the SBT is shorter and easier to score and is an appropriate alternative for identifying high risk LBP patients in primary care.