Associations of the modified STarT back tool and Hospital Anxiety and Depression Scale (HADS) with gait speed and knee pain in knee osteoarthritis: a retrospective cohort study

Abstract

Objective The association of the modified STarT Back Tool (mSBT) psychosocial measure with gait speed and knee pain in knee osteoarthritis is not well defined. This study aimed to, in patients with knee osteoarthritis, (i) examine the convergent validity of mSBT with the Hospital Anxiety and Depression Scale (HADS) and (ii) compare the predictive validity of mSBT and HADS with gait speed and knee pain. Methods We performed a retrospective cohort analysis of mSBT, HADS, gait speed, and knee pain outcomes data collected from 119 patients who received outpatient physical therapy. Of these patients who were evaluated at their first (baseline) physical therapy visit, 55 had available data at the Week-16 follow-up visit. Results mSBT and HADS showed moderately strong pairwise correlations (Spearman correlation > 0.57; p < 0.001). After adjusting for age, sex, body weight, and knee impairment variables in multivariable linear mixed-effects analyses, mSBT was associated with gait speed (p < 0.001) and knee pain intensity (p < 0.001) and it had comparable strength of association as HADS. In within-patient regression analyses, change in mSBT was associated with changes in gait speed (p = 0.04) and knee pain (p = 0.01) over 16 weeks. Conclusion The mSBT had convergent validity with HADS and it showed predictive validity with gait speed and knee pain in knee osteoarthritis. Although broader validation is required, the 5-item mSBT psychosocial measure may be applied as part of routine clinical care to assess psychological distress in patients with knee osteoarthritis. IMPLICATIONS FOR REHABILITATION The 5-item psychosocial subscale of the modified STarT Back tool (mSBT) showed good convergent validity with the 14-item Hospital Anxiety and Depression Scale in patients with knee osteoarthritis. The mSBT psychosocial subscale showed predictive validity, at both cross-sectional and longitudinal levels, with gait speed and knee pain in patients with knee osteoarthritis. The mSBT can potentially be used in the busy clinical setting to assess psychological distress in patients with knee osteoarthritis.