Factors Associated with Sarcopenia Among Vietnamese Elderly Outpatients with Chronic Musculoskeletal Disorders: A Cross-Sectional Study

Background/Objectives: Sarcopenia may compound mobility limitations and fall vulnerability among older adults with coexisting knee osteoarthritis (KOA) and chronic spinal pain. This secondary analysis of a previously reported or substantially overlapping cohort estimated the proportion meeting Asian Working Group for Sarcopenia (AWGS) 2019 criteria and explored additional adjusted associations in a selected Vietnamese outpatient sample. Methods: A hospital-based secondary cross-sectional analysis included 88 outpatients aged ≥60 years (mean age, 70.5 ± 6.7 years; 69 women, 78.4%) with coexisting KOA and chronic spinal pain who were recruited by convenience sampling at Thai Binh General Hospital from May to October 2024. Source-record verification confirmed that all of the analytic participants had both diagnoses. Their muscle mass, grip strength, and gait speed were assessed using the InBody 770, an InGrip handgrip dynamometer, and a 15-foot walk test, respectively. The prespecified primary classification used AWGS 2019. The AWGS 2025 framework was considered during revision, but numerical reclassification was not feasible because the retained participant-level analytic dataset contained the derived AWGS 2019 outcome and covariates used in the reported regression and CHAID analyses, but not the original continuous age, appendicular skeletal muscle mass index, handgrip values, or a complete raw component record sufficient to independently reconstruct the AWGS 2019 status or apply AWGS 2025 thresholds. Multivariable logistic regression and CHAID were treated as exploratory. Results: Under AWGS 2019, 36/88 participants (40.9%) had sarcopenia, including 15 (17.0%) with severe sarcopenia. All 88 participants had both KOA and chronic spinal pain; therefore, diagnostic-category subgroup comparisons were not applicable. In the exploratory adjusted analysis, an age >70 years (adjusted odds ratio [AOR]: 9.00, 95% confidence interval [CI]: 2.40–33.60), a history of falls (AOR: 6.33, 95% CI: 2.77–14.45), low educational attainment (AOR: 2.86, 95% CI: 1.46–5.61), and a higher Pittsburgh Sleep Quality Index score (AOR: 1.16, 95% CI: 1.02–1.32) remained associated with sarcopenia. Wide CIs and approximately 4.5 events per regression coefficient indicated substantial imprecision. Conclusions: This secondary report provides setting-specific descriptive evidence rather than independent replication, a validated prediction tool, or a fully auditable reconstruction of the original AWGS component measurements. Because AWGS 2025 reclassification could not be reconstructed from the retained dataset and raw component records, the AWGS 2019 estimate should not be treated as directly interchangeable with the estimates generated under the updated framework. The observed associations and within-sample subgroup patterns require confirmation in larger, prospectively auditable studies.