The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) as a predictor of all-cause and cardiovascular mortality in US adults with diabetes or prediabetes: NHANES 1999-2018

BackgroundThe non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) serves as a novel composite lipid indicator for atherosclerosis. However, the association between NHHR and mortality in patients with diabetes or prediabetes remains unclear. Consequently, the objective of this study was to investigate the relationship between NHHR and both all-cause and cardiovascular mortality in US adults with diabetes or prediabetes.MethodsThis study included 12,578 adult participants with diabetes or prediabetes from the US National Health and Nutrition Examination Survey (1999-2018). Mortality outcomes were ascertained by linking to the National Death Index (NDI) record up to December 31, 2019. We employed a weighted multivariate Cox proportional hazards model and restricted cubic splines to assess the associations between NHHR and all-cause and cardiovascular mortality. A segmented Cox proportional hazards model was used for evaluating threshold effects. Furthermore, a competing risks analysis was performed to explore the relationship between NHHR and cardiovascular mortality.ResultsDuring a median follow-up period of 8.08 years, 2403 participants encountered all-cause mortality, with 662 of them specifically succumbing to cardiovascular mortality. The restricted cubic splines revealed a U-shaped association between NHHR and all-cause mortality, while an L-shaped association was observed for cardiovascular mortality. The analysis of threshold effects revealed that the inflection points for NHHR and all-cause and cardiovascular mortality were 2.72 and 2.83, respectively. Specifically, when the baseline NHHR was below the inflection points, a negative correlation was observed between NHHR and both all-cause mortality (HR: 0.76, 95% CI: 0.68-0.85) and cardiovascular mortality (HR: 0.70, 95% CI: 0.57-0.85). Conversely, when the baseline NHHR exceeded the inflection points, a positive correlation was observed between NHHR and both all-cause mortality (HR: 1.11, 95% CI: 1.06-1.16) and cardiovascular mortality (HR: 1.08, 95% CI: 1.00-1.16).ConclusionsAmong US adults with diabetes or prediabetes, a U-shaped association was observed between NHHR and all-cause mortality, whereas an L-shaped association was identified with cardiovascular mortality. The inflection points for all-cause and cardiovascular mortality were 2.72 and 2.83, respectively.