Linear and non-linear relationships between red blood cell indices and cardiovascular risk factors: findings from the China National Health Survey

Abstract Introduction Cardiovascular diseases (CVDs) are a leading cause of mortality worldwide. Red blood cell indices (RBIs) are associated with CVD risk factors (CRFs) and easy to test, making them useful as a screening tool for early identification of individuals at high risk for CVDs. Methods Data from 31,781 participants in the China National Health Survey conducted from 2012 to 2017 were analyzed. Linear and non-linear relationships between RBIs and CRFs (hyperuricemia, diabetes, dyslipidemia) were assessed using restricted cubic splines. Propensity score weighting was used to balance confounders between RBI groups in the multivariable logistic regression models. Results Hemoglobin concentration, red blood cell count and hematocrit all showed a significant linear dose-response association with all CRFs (p values < 0.001). Higher RBIs levels were associated with increased risk of hyperuricemia, diabetes, high LDL, high triglycerides, and high total cholesterol, but decreased HDL. For example, compared to the lowest quantile of HGB, the highest quantile had a 26% (13-40%) higher risk for hyperuricemia, a 43% (25-63%) higher risk of diabetes, 87% (61%-1.18 fold) higher risk of high LDL, and 68% (52-85%) higher risk of high triglycerides. Non-linear relationships were revealed between RBIs and most CRFs except uric acid and glucose. Sex differences were observed, with stronger associations between RBIs and hyperuricemia in women but stronger links with high LDL in men. Conclusions Elevated RBIs indicated higher risk of multiple CRFs. These findings suggest incorporating RBIs into CVD screening strategies to facilitate early prevention efforts, with consideration of sex differences.