Prognostic factors for premature cardiovascular disease mortality in Malaysia: A modelling approach using semi-parametric and parametric survival analysis with National Health and Morbidity Survey linked mortality data

Abstract

Abstract Background Cardiovascular disease (CVD) is the leading cause of premature mortality worldwide, with a pronounced impact in low- and middle-income countries. Despite existing research on CVD risk factors, the study of premature CVD mortality in Malaysia remains limited. This study employs survival analysis to model modifiable risk factors associated with premature CVD mortality among Malaysian adults. Method We utilised data from Malaysia's National Health and Morbidity Survey (NHMS) conducted in 2006, 2011, and 2015, linked with mortality records. The cohort comprised individuals aged 18 to 70 during the NHMS interview. Follow-up extended to 2021, with the primary event of interest being CVD-related premature mortality between ages 30 and 70. This study employed six survival models: a semi-parametric Cox proportional hazard (PH) and five parametric survival models, which were Exponential, Weibull, Gompertz, log-normal and log-logistic distributions using R software. The age standardized incidence rate (ASIR) of premature CVD mortality was calculated per 1000 person-years. Results Among 63,722 participants, 886 (1.4%) experienced premature CVD mortality, with an ASIR of 1.80 per 1000 person-years. The best-fit models (based on AIC value) were the stratified Cox model by age (semi-parametric) and the log-normal accelerated failure time (AFT) model (parametric). Males had higher risk (Hazard Ratio, HR = 2.68) and experienced 49% shorter survival time (Event Time Ratio, ETR = 0.51) compared to females. When compared to Chinese ethnicity, Indians, Malays, and other Bumiputera had higher HR and lower survival times. Rural residents and those with lower education also faced increased HRs and reduced survival times. Diabetes, both diagnosed (HR = 3.26, ETR = 0.37) and undiagnosed (HR = 1.63, ETR = 0.63), increased mortality risk and decreased survival time by 63% and 37%, respectively. Diagnosed and undiagnosed hypertension elevated risk (HR = 1.84, 1.46) and reduced survival time by 47% and 32% (ETR = 0.53, 0.68) respectively. Undiagnosed hypercholesterolemia increased risk (HR = 1.31) and lowered survival time by 20% (ETR = 0.80), with no significant association for diagnosed hypercholesterolemia. Additionally, current smoking and abdominal obesity elevated risk (HR = 1.38, 1.60) and shortened survival (ETR = 0.81, 0.71). Conclusion The semi-parametric and parametric survival models both highlight the considerable impact of socioeconomic status and modifiable risk factors on premature CVD mortality, underscoring the imperative for targeted interventions to effectively mitigate these effects.