Abstract
BACKGROUND: Inflammation plays an important role in the pathogenesis of coronary heart disease (CHD) and asthma. We sought to find out whether complete blood count-derived inflammatory markers such as the platelet-lymphocyte ratio (PLR), neutrophil-lymphocyte ratio (NLR), and monocyte-lymphocyte ratio (MLR) were associated with the incidence of CHD in patients with asthma. METHODS: This study analyzed data from the National Health and Nutrition Examination Survey (NHANES) spanning from 1999 to 2018. Participants included in the analysis were those aged 20 years and older with a self-reported history of asthma, while pregnant women and individuals with a history of malignancy were excluded. The PLR, NLR, and MLR were calculated based on complete blood count results. Patients were stratified into two groups based on the presence or absence of CHD, and weighted baseline characteristics of asthma patients were investigated. Subsequently, weighted multivariate logistic regression analysis and threshold effect analysis were employed to explore potential linear or nonlinear relationships between inflammatory markers and asthma patients with CHD. Subgroup analyses were conducted based on factors such as gender, age, and diabetes to examine the consistency of results across different subgroups. RESULTS: From 1999 to 2018, the NHANES identified 4,300 asthma patients, which represented an estimated 19,966,780 individuals. The cohort was divided into two groups based on the presence of CHD: the CHD group (651,835 participants) and the non-CHD group (19,314,945 participants). The comparison between the two groups revealed statistically significant differences in NLR and MLR, but no significant differences in PLR. Using weighted multivariate logistic regression analysis, categorical variables (PLR, NLR, and MLR) were divided into two groups based on their optimal cutoffs. After adjusting for confounding factors, only PLR showed a significant association with CHD prevalence. Further threshold effect analysis demonstrated a nonlinear relationship between PLR and CHD in asthma patients. A critical inflection point was observed at PLR =128. Specifically, for PLR values below 128, each unit increase in PLR was associated with a 0.992-fold decrease in CHD prevalence. Conversely, for PLR values above 128, each unit increase in PLR was associated with a 1.007-fold increase in CHD prevalence. Subgroup analyses confirmed the robustness of these findings, showing consistent results across different strata of asthma patients. CONCLUSIONS: In asthma patients, PLR shows a nonlinear relationship with CHD. Clinically, this suggests that PLR may help identify asthma patients who are at either lower or higher possibility of cardiovascular occurrence, depending on their PLR level, and could assist in guiding more tailored preventive strategies.