Exploring the role of the built environment and psychosocial mediators on knee function in knee osteoarthritis patients in Singapore: a cross-sectional study

Objectives: (1) To examine if a more accessible built environment (BE) is significantly associated with better knee function outcomes in knee osteoarthritis (OA) patients. (2) To assess if the relationship between BE and knee function is mediated by fear of movement and self-efficacy.

Design: Cross-sectional study.

Setting: Two tertiary hospitals in Singapore.

Participants: 212 knee OA patients (mean: 63.81±8.27 years old), majority female (69.8%).

Inclusion criteria: (i) meets National Institute for Health and Care Excellence criteria for knee OA, (ii) independent community ambulant.

Exclusion criteria: (i) alternative diagnosis to knee OA, (ii) secondary osteoarthritis, (iii) severe medical and/or cognitive comorbidity impairing activities of daily living, (iv) previous knee arthroplasty, (v) wheelchair bound, or (vi) pregnant. PRIMARY AND SECONDARY OUTCOME MEASURES; STATISTICS: How self-efficacy (Arthritis Self-Efficacy Scale-8 (ASES-8)) and fear of movement (Brief Fear of Movement (BFOM)) mediates impact of overall BE (IPAQ-Environment module: Access to Destinations) and five item-specific domains of BE accessibility on knee function (Knee Injury and Osteoarthritis Outcome Score-12 (KOOS-12)). For variables significantly correlated with BE and KOOS-12 in bivariate Pearson correlation tests, mediation analysis was performed with confounders adjusted.

Results: Total BE (r=0.142, p=0.038) and accessibility to transit station (r=0.161, p=0.019) were positively correlated with KOOS-12. Structural barriers (r=-0.138, p=0.045) were negatively correlated with KOOS-12. ASES-8 was a significant mediator in the relationship between accessibility to transit station and KOOS-12 (coeff=0.87, 95% CI=(0.24, 1.69), p=0.005) and between total BE and KOOS-12 (coeff=0.25, 95% CI=(0.10, 0.45), p=0.004). BFOM was a marginally significant mediator between structural barriers and KOOS-12 (coeff=-0.36, 95% CI=(-0.86, -0.02); p=0.054).

Conclusion: More accessible BE and lesser structural barriers in the BE are associated with better knee function. Self-efficacy mediates the relationship between overall BE accessibility and knee function. Fear of movement mediates the negative association between barriers in the BE and knee function.Applications include assessing BE barriers and psychosocial mediators in clinician consultations, developing multidisciplinary integrated care models and urban designers planning mobility friendly BEs.

Trial registration number: The study has been registered under clinicaltrials.gov registry (Identifier: NCT04942236).