Association between sarcopenic obesity and the risk of knee osteoarthritis in the middle-aged and elderly Chinese population: A 7-year cohort study

Objective

To investigate the relationship between sarcopenic obesity and the risk of knee osteoarthritis (KOA) in middle-aged and elderly individuals.

Methods

This study utilized cohort data from the China Health and Retirement Longitudinal Study (CHARLS) database, focusing on middle-aged and elderly individuals without knee osteoarthritis in 2011. A total of 4299 participants aged over 45 who met the inclusion and exclusion criteria were included. Using overweight as the criterion for obesity, participants were divided into four groups: normal control, only overweight, only sarcopenia, and sarcopenic overweight. Cox proportional hazards models were employed for survival analysis, comparing the normal control group with the other three groups to assess their impact on the risk of developing knee osteoarthritis. Sensitivity analyses were conducted using sarcopenia obese and sarcopenia abdominal obesity to ensure the robustness of the results. Additionally, subgroup analyses were performed to explore the influence of different populations on the outcomes. Lastly, we investigated the association between probable sarcopenic obesity and KOA.

Results

Compared to the normal control group, the sarcopenic obesity group showed a significantly increased risk of KOA Hazard Ratio (HR) = 1.53, 95 % Confidence interval (CI) = 1.19–1.98). Sensitivity analyses demonstrated consistent patterns, with the sarcopenic obese group showing a 57 % elevated risk of KOA (HR = 1.57, 95%CI = 1.04–2.35) and the sarcopenic abdominal obesity group a 40 % increased risk (HR = 1.40, 95%CI = 1.08–1.80), both relative to the normal control cohort. Subgroup analyses revealed a significant interaction effect of gender on the results (P for interaction <0.05), with females in the sarcopenic overweight group showing a statistically significant difference compared to the normal group (HR = 1.45, 95 % CI = 1.06–1.99). Moreover, in the context of probable sarcopenic overweight and KOA, the probable sarcopenic overweight group (HR = 1.44, 95 % CI = 1.11–1.87) was associated with an increased risk of developing KOA.

Conclusion

This study is the first longitudinal investigation to examine the association between sarcopenic obesity (and probable sarcopenic obesity) and the risk of KOA in a large sample of middle-aged and elderly individuals. The findings suggest that through weight management and adequate muscle strength, it may be probable to reduce the risk of KOA in middle-aged and elderly populations, especially among women, thereby improving quality of life in later years.