A link between systemic low-grade inflammation and frailty in older adults: clinical evidence from a nationwide population-based study.

Abstract

Despite the possible role of systemic low-grade inflammation on frailty, the majority of previous studies have focused solely on the phenotypic frailty with limited participant numbers, thereby weakening the evidence supporting the notion that circulating C-reactive protein (CRP) could be a potential frailty biomarker. This study is a nationally representative, population-based, cross-sectional analysis from the Korea National Health and Nutrition Examination Survey, involving 5,359 participants aged 65 and older. We generated a deficit accumulation frailty index (FI) based on 38 items, encompassing physical, cognitive, psychological, and social status. Frailty was classified as non-frail (FI ≤ 0.15), pre-frail (0.15 < FI ≤ 0.25), or frail (FI > 0.25). Serum high-sensitivity CRP (hsCRP) levels were measured by immunoturbidometric method. After adjusting for confounders including age, sex, income, education, smoking, hypertension, diabetes, dyslipidemia, stroke, cardiovascular diseases, and body mass index, serum hsCRP levels were 29.4% higher in frail participants compared to their non-frail counterparts (p = 0.001). Additionally, circulating hsCRP concentrations positively correlated with the FI (p = 0.003), and the odds ratio for frailty per standard deviation increase in serum hsCRP was 1.18 (p = 0.001). Moreover, older adults in the highest hsCRP quartile exhibited a significant higher FI with a 1.59-fold increased odds ratio for frailty than those in the lowest quartile (p = 0.002 and 0.001, respectively). These findings validate the impact of age-related systemic low-grade inflammation on frailty and support the utility of serum hsCRP as a potential biomarker for detecting frailty in older adults.