Effect of Small Dense Low‐Density Lipoprotein Cholesterol Combined With High‐Sensitivity C‐Reactive Protein on Cardiometabolic Multimorbidity: A National Cohort Study

Background Small dense low‐density lipoprotein cholesterol (sdLDL‐C) is a more significant atherosclerotic factor than LDL‐C. This investigation aimed to examine the correlation between sdLDL‐C levels and the risk of cardiometabolic multimorbidity (CMM) in middle‐aged and older adults. Methods Participants aged ≥ 45 years who did not have CMM at baseline from the China Health and Retirement Longitudinal Study (CHARLS) data set were included in this cohort study. The baseline data of the participants were collected in 2011 and followed up until 2020. sdLDL‐C is calculated using a validated formula. The relationship of sdLDL‐C with CMM risk was examined using Cox regression analyses. The combined effect of high‐sensitivity C‐reactive protein (hsCRP) and sdLDL‐C on CMM risk was explored. Results A total of 9616 participants were included, of whom 1814 (18.86%) had CMM and 7802 (81.14%) did not have CMM. Elevated sdLDL‐C levels were correlated with a higher risk of CMM (HR [95% CI] = 1.10 [1.04−1.15]). The interaction terms for sdLDL‐C and hsCRP presented that participants in the low sdLDL‐C and high hsCRP group (HR [95% CI] = 1.21 [1.03‐1.41]), the high sdLDL‐C and low hsCRP group (HR [95% CI] = 1.21 [1.08−1.36]), and the high sdLDL‐C and high hsCRP group (HR [95% CI] = 1.36 [1.15−1.62]) had a higher risk of CMM versus the low sdLDL‐C and low hsCRP group, and the trend for these interaction terms was significant (P trend = 0.031). Conclusion Elevated sdLDL‐C levels were related to an increased risk of CMM, and there was an interaction between sdLDL‐C and hsCRP on the increased risk of CMM.