Symptomatic knee osteoarthritis in older Thai adults: prevalence, risk factors, and associations with osteoporosis, sarcopenia, and fall risk—a nationwide cross-sectional study

Thailand’s rapidly aging population is driving a growing burden of age-related conditions, including knee osteoarthritis (OA), a leading cause of disability in older adults. Nationwide data on symptomatic knee OA and its overlap with osteoporosis and sarcopenia remain limited. We estimated prevalence and risk factors for symptomatic knee OA and quantified concurrent osteoporosis, sarcopenia, and fall risk in community-dwelling older adults across Thailand. This study is a secondary analysis of data from a cross-sectional survey conducted between March 2021 and August 2022, which employed stratified multistage sampling across six geographic regions of Thailand. Community-dwelling adults aged ≥ 60 years were included. Symptomatic knee OA was diagnosed using American College of Rheumatology clinical criteria. Demographic, clinical, and functional data—including comorbidities, quality of life, and fall risk—were collected. Osteoporosis was assessed by dual-energy X-ray absorptiometry using World Health Organization criteria, and sarcopenia by bioelectrical impedance analysis with Asian Working Group for Sarcopenia 2019 criteria. Associations were analyzed using multivariable logistic regression. Among 2947 participants (mean age 69.2 years; 63.3% women), the prevalence of symptomatic knee OA was 53.8%. Participants with OA had higher osteoporosis prevalence (31.7% vs. 27.4%; P = .002) but lower sarcopenia prevalence (15.1% vs. 20.6%; P = .002). They reported lower EuroQol 5-Dimension index and visual analog scale scores and more falls and high fall risk. Female sex, older age, and obesity (body mass index ≥ 25 kg/m2) were independent risk factors. Glucocorticoid exposure was also associated (multivariable odds ratio 2.147; P = .002). Other comorbidities were not independently associated. Symptomatic knee OA affects more than half of Thailand’s older adults and coexists with substantial bone–muscle health burden. These findings support risk-stratified screening; routine osteoporosis assessment within OA care; fall-prevention and weight-management measures; and preoperative bone health optimization for arthroplasty candidates. Prioritizing integrated, multidisciplinary pathways could reduce disability and health care costs in Thailand’s rapidly aging society.