The non-linear relationship between atherogenic index of plasma and stroke: a study among middle-aged and elderly Chinese adults with depression

BACKGROUND: Existing evidence supports a connection between the atherogenic index of plasma(AIP) and increased stroke risk, however, few investigations have specifically examined this relationship among Chinese adults aged ≥ 45 with depression. METHODS: This research utilized a comprehensive, nationally representative dataset collected from 2011 to 2018. The cross-sectional analysis included 4,055 samples. In the retrospective cohort study, 2,861 participants who had no stroke at baseline were selected and followed up for the development of stroke. Variables including age, AIP, gender, place of residence, marital condition, education, smoking, alcohol intake, diabetes, heart problem, and hypertension were compared between stroke patients and non-stroke patients among depressed individuals. Multivariable logistic regression modeling is used to further assess the association between AIP and stroke in individuals with depression after adjusting for confounding factors. Subgroup analysis was conducted to observe the connection between AIP and stroke among specific lifestyle habits (smoking, drinking) groups, and further threshold analysis was performed to test for any non-linear relationship. RESULTS: The cross-sectional results show that when comparing those with stroke to those without stroke, a notable disparity in AIP levels is observed (p < 0.001). Results from multiple regression analysis demonstrated a remarkable positive association between AIP and the likelihood of stroke. This association persisted in the final multivariable-adjusted model (adjusting for 6 covariates), where AIP retained significance(p = 0.016). In the retrospective cohort study, AIP was positively correlated with the risk of stroke in the depressed population (OR = 1.83, 95% CI 1.27–2.63, p = 0.001), and a similar trend was observed in the high AIP group (OR = 1.69, 95% CI 1.17–2.44, p = 0.006), which was consistent with the cross-sectional results. Results from subgroup analysis revealed a positive association between AIP and stroke among never-smokers(OR = 2.16; 95% CI 1.15–4.06, p = 0.017) and non-alcohol(OR = 1.97; 95% CI 1.15–3.39, p = 0.014) consumers, while threshold effects and curve fitting showed a non-linear relationship. CONCLUSION: Following covariate adjustment, AIP was positively associated with stroke risk in depressed individuals, while subgroup analyses revealed a non-linear relationship in those with specific lifestyles.