Physical activity and cost of care among adults with diabetes and musculoskeletal disorders in Kaduna State Nigeria

Musculoskeletal disorders (MSDs) are common among adults with diabetes, yet their economic impact in low-resource settings is poorly characterised. This study assessed MSD distribution, examined associations between physical activity and cost of care, and identified factors associated with healthcare expenses among diabetic adults in Kaduna State, Nigeria. A hospital-based cross-sectional study was conducted among 409 adults with clinically diagnosed diabetes mellitus and physician-diagnosed MSD at a single tertiary referral centre. Data were collected using structured questionnaires including the International Physical Activity Questionnaire Short Form (IPAQ-SF). Physical activity was measured in MET-minutes/week using the official IPAQ-SF scoring algorithm. The cost of care comprised direct costs (consultation, medication, laboratory tests, imaging, physiotherapy, hospitalisation, transport) and indirect costs (productivity losses from absenteeism and presenteeism), valued using the human-capital approach over the previous three months. Data were analysed using descriptive statistics, t-tests with Cohen’s d effect sizes, Spearman correlation with Bonferroni correction (α = 0.0018 for 28 pairwise correlations), and generalised linear models (GLMs) with gamma distribution and log link. Among 409 participants (mean age 59.0 ± 5.9 years; 63.1% female), knee disorders (57.9%) and foot disorders (25.9%) predominated. Participants had a median (IQR) total physical activity of 693 (198–1680) MET-min/week; 68.2% were classified as low, 22.7% moderate, and 9.0% high. The median total cost of care was ₦18,500 (IQR ₦7,200–42,300). Thirty-seven participants (9.0%) reported zero cost. Higher physical activity was associated with lower total cost of care (β = −0.048; 4.7% lower total cost; p = 0.011) and lower direct cost (5.6% lower; p = 0.018). Self-employment was associated with 38% higher indirect costs ( p = 0.004). Effect sizes for low versus high physical activity were Cohen’s d = 0.42 and 0.41, both p < 0.001. Adjustment for education, occupation, diabetes duration, and complications left the physical activity coefficient essentially unchanged (0.048 vs. 0.044–0.046). Higher physical activity was associated with lower cost of care among adults with diabetes and MSDs. The cross-sectional design, same-interview self-report, and selection through clinic attendance preclude causal inference; the findings are presented as hypotheses for longitudinal research.