C-reactive Protein, but Not Neutrophil-Lymphocyte Ratio, is Inversely Associated with Muscle Strength Only in Older Men: NHANES 1999–2002

To evaluate the association of inflammation (C-reactive protein (CRP) and neutrophil-lymphocyte ratio (NLR) levels) with muscle strength in older adults. We also aimed to evaluate whether these associations are sex -specific. A cross-sectional study was performed with data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2001-2002. A total of 2387 individuals over 50 years of both sexes were evaluated, according to the eligibility criteria for the strength test. Muscle strength was measured by Kinetic Communicator isokinetic dynamometer; while the NLR was obtained by the ratio of the total neutrophil for lymphocyte count and CRP was quantified by latex nephelometry. Linear regression analyses, crude and adjusted for confounders, were used to estimate the coefficients and 95 % confidence intervals for peak strength (muscle strength) by tertiles of NLR and CRP. There was no association between NLR and peak strength for both sexes. CRP levels were inversely associated with peak force in men [2nd tertile beta =-3.33 (-15.92; 9.25); 3rd tertile beta =-24.69 (-41.18;-8.20), p for trend = 0.005], but not in women [2nd tertile beta =-3.22 (-15.00; 8.56); 3rd tertile beta =-9.23 (-28.40;-9.94), p for trend = 0.332]. In conclusion, NLR levels were not associated with muscle strength in both sexes. CRP levels were inversely associated with muscle strength in older men, but not in women, suggesting that the association between inflammation and muscle strength in older adults can be sex -specific.