Sex-specific differences between C-reactive protein and appendicular lean soft tissue index in heart failure: findings from the National Health and Nutrition Examination Survey

Introduction Heart failure (HF) is often accompanied by muscle wasting and elevated C-reactive protein (CRP). This study aimed to examine the association between CRP and appendicular lean soft tissue index (ALSTI) in patients with HF, focusing on potential sex differences.Methods Using data from the National Health and Nutrition Examination Survey (NHANES), 73 HF patients (36 males, 37 females) aged ≥18 years were analysed. ALSTI was calculated using lean soft tissue adjusted for height squared (kg/m2), and CRP was measured via latex-enhanced nephelometry; higher CRP defined as the top 50th percentile of the cohort. Linear regression models were employed to assess the association between CRP and ALSTI.Results Higher CRP was not associated with ALSTI in unadjusted models (p = 0.39), but fully adjusted models revealed a significant negative association (b = -0.41 kg/m2, 95% CI -0.79 to -0.02, p = 0.04). Sex-stratified analyses showed a link in males (b = -0.69 kg/m2, 95% CI -1.23 to -0.16, p = 0.01), but not females (p = 0.47). In patients ≥50 years, similar findings were shown (males → b = -0.70 kg/m2, 95%CI −1.33 – −0.08, p = 0.03; females → b = 0.69 kg/m2, 95%CI -1.59 − 2.96, p = 0.51). Elevated CRP demonstrated significantly negative female-male associations with ALSTI for both 18-59- and 50–59-year-olds (p < 0.01).Conclusions CRP is associated with ALSTI in males with HF, highlighting the need for sex-specific investigations through longitudinal and experimental studies.