Association between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and carotid plaque: a retrospective cohort study

Objective To investigate the association between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and the risk of carotid plaque (CP). Methods In this cohort study, 5,985 adults aged ≥18 years without baseline CP were selected from the Dalian Health Management Cohort (2015–2023). Participants were categorized into quartiles according to NHHR levels. Kaplan–Meier curves were used to estimate cumulative CP incidence. Cox proportional hazards models and restricted cubic spline (RCS) analyses were applied to evaluate the association between NHHR and CP risk. Subgroup and sensitivity analyses were conducted to assess the robustness of the findings. Results During 11,725.34 person-years of follow-up (mean follow-up: 2.24 years), 780 participants (13.03%) developed CP. Compared with participants in the lowest NHHR quartile, those in the highest quartile had a significantly increased risk of CP (HR = 1.64, 95% CI: 1.26–2.14; p < 0.001). When treated as a continuous variable, NHHR remained independently associated with CP risk (HR = 1.11, 95% CI: 1.04–1.18; p = 0.001). RCS analysis demonstrated a nonlinear positive association (P for nonlinearity = 0.003), with an inflection point at NHHR = 4.071. Significant interactions were observed for age, sex, and hypertension status (all P for interaction < 0.05), with stronger associations among individuals aged <45 years, females, and normotensive participants. Sensitivity analyses confirmed the robustness of the results. Conclusion Elevated NHHR is independently associated with an increased risk of CP, with effect modification by age, sex, and hypertension status. NHHR may serve as a simple and noninvasive biomarker for early risk stratification of CP.