[Association between body composition and high-sensitivity C-reactive protein in older adults aged 65 years and above in 18 longevity areas in China].

Elevated hs-CRP (>3.0 mg/L) was detected in 28.0% of older adults aged 65 years and above in 18 longevity areas in China.

• A total of 4,596 older adults were included in the study.
• Mean age was 82.61±10.55 years.
• 2,185 (47.5%) were men.
• 1,287 older adults (28.0%) had elevated hs-CRP.

Higher muscle mass was associated with a significantly lower risk of elevated hs-CRP in older adults after adjustment for confounders.

• The Q4 (highest) muscle mass group showed 32.8% lower risk of elevated hs-CRP compared with the Q1 (lowest) group.
• OR=0.672, 95%CI: 0.518-0.869.
• Body composition was measured using bioelectrical impedance analysis.
• Multivariable logistic regression was used with adjustment for confounders.

Higher fat mass was associated with a significantly increased risk of elevated hs-CRP in older adults.

• The Q4 fat mass group showed 54.7% higher risk of elevated hs-CRP compared with the Q1 group.
• OR=1.547, 95%CI: 1.189-2.012.
• This association was observed after adjustment for confounders using multivariable logistic regression.

Higher body fat percentage was associated with a significantly increased risk of elevated hs-CRP.

• The Q4 body fat percentage group showed 43.2% higher risk compared with the Q1 group.
• OR=1.432, 95%CI: 1.141-1.799.
• Body fat percentage was measured using bioelectrical impedance analysis.

Higher visceral fat level was associated with the greatest increased risk of elevated hs-CRP among the fat-related body composition indicators.

• The Q4 visceral fat level group showed 73.8% higher risk of elevated hs-CRP compared with the Q1 group.
• OR=1.738, 95%CI: 1.358-2.226.
• This was the largest effect size among the four body composition indicators examined.

All four body composition indicators showed significant nonlinear dose-response relationships with elevated hs-CRP risk.

• Restricted cubic spline models were used to evaluate dose-response relationships.
• Significant nonlinear relationships were found for muscle mass, fat mass, body fat percentage, and visceral fat level.
• All P<0.05 for nonlinearity.

The association between muscle mass and elevated hs-CRP risk was sex-specific, being significant only in men.

• In men, the Q4 muscle mass group showed 43.7% reduced risk of elevated hs-CRP compared with Q1 (OR=0.563, 95%CI: 0.408-0.774).
• In women, no statistically significant association was observed between muscle mass and elevated hs-CRP risk.
• Subgroup analysis was stratified by sex.

The association between fat mass and elevated hs-CRP risk was sex-specific, being significant only in women.

• In women, the Q4 fat mass group showed 82.5% increased risk of elevated hs-CRP compared with Q1 (OR=1.825, 95%CI: 1.243-2.678).
• In men, no statistically significant association was observed between fat mass and elevated hs-CRP risk.
• These sex-specific differences were identified through subgroup analysis.