A Higher Skeletal Muscle Mass and Lower Adiposity Phenotype Is Associated with Better Cardiometabolic Control in Adults with Hip and Knee Osteoarthritis: Results from the Chilean National Health Survey 2016–2017

Objective: This study aimed to (1) characterize cardiometabolic factors in self-reported hip and knee osteoarthritis (OAD) across four body composition phenotypes defined by muscle mass and adiposity, and (2) associate risk factors with diabetes and hypertension (HTN). Methods: A cross-sectional analysis of the Chilean National Health Survey 2016–17 (n = 4996) stratified participants into four groups: low skeletal muscle mass/high waist circumference (Low-SMM/High-WC), low SMM/low WC (Low-SMM/Low-WC), high SMM/high WC (High-SMM/High-WC), and high SMM/low WC (reference group). Each group was further divided into subgroups with or without diagnosed hip or knee OAD. The main outcomes were fasting plasma glucose, systolic (SBP)/diastolic (DBP) blood pressure (continuous outcomes), and other secondary factors such as cardiovascular risk (CVR). Results: In the hip OAD subgroup, the Low-SMM/High-WC groups had significantly higher SBP versus the reference value (145 vs. 127 mmHg, p < 0.0001, diff +18 mmHg). In the knee OAD subgroup, the Low-SMM/High-WC groups had significantly higher SBP versus the reference value (141 vs. 134 mmHg, p < 0.0001, diff +7 mmHg). The SBP showed a significant interaction between the group and OAD diagnosis (p = 0.007 hip OAD; p < 0.0001 knee OAD). Conclusions: Hip and knee OAD associates with elevated SBP/DBP in older adults. OAD groups showed an OR above 2 for diabetes, 2.7 for HTN, 4.5 for metabolic syndrome, and over 2 for moderate-to-high cardiovascular risk. OAD interacts substantially with cardiometabolic factors, especially in low muscle mass/high adiposity phenotypes. Lifestyle optimization of physical activity and nutrition to preserve muscle mass and mitigate adiposity is essential for cardiometabolic health promotion in OAD patients.