Subgrouping for patients with low back pain: a multidimensional approach incorporating cluster analysis and the STarT...

Early screening for psychological distress has been suggested to improve patient management for individuals experiencing low back pain. This study compared 2 approaches to psychological screening (ie, multidimensional and unidimensional) so that preliminary recommendations on which approach may be appropriate for use in clinical settings other than primary care could be provided. Specifically, this study investigated aspects of the STarT Back Screening Tool (SBT): 1) discriminant validity by evaluating its relationship with unidimensional psychological measures and 2) construct validity by evaluating how SBT risk categories compared to empirically derived subgroups using unidimensional psychological and disability measures. Patients (N = 146) receiving physical therapy for LBP were administered the SBT and a battery of unidimensional psychological measures at initial evaluation. Clinical measures consisted of pain intensity and self-reported disability. Several SBT risk-dependent relationships (ie, SBT low < medium < high risk) were identified for unidimensional psychological measure scores, with depressive symptom scores associated with the strongest influence on SBT risk categorization. Empirically derived subgroups indicated that there was no evidence of distinctive patterns among psychological or disability measures other than high or low profiles; therefore, 2 groups may provide a clearer representation of the level of pain-associated psychological distress, maladaptive coping, and disability in this setting compared with 3 groups as suggested when using the SBT in primary care settings.

This study suggests that the SBT can replace administering several unidimensional psychological measures as a first-line screening measure for psychological distress. However, clinicians need to be aware of the potential for misclassification with SBT results when compared to unidimensional measures. This study also suggests that a modified SBT risk stratification scheme based on empirically derived subgroups could potentially assist in identifying elevated levels of pain-associated psychological distress, maladaptive coping, and disability in practice settings outside of primary care. Patients identified with elevated levels of pain-associated distress and maladaptive coping may be indicated for additional assessment using construct-specific questionnaires.