Short-term socioeconomic status shift and long-term cardiovascular outcomes in China: a population-based cohort study

Introduction Limited studies have discussed the effect of socioeconomic status (SES) shift on cardiovascular outcomes, especially in less developed regions and countries. We; therefore, explored the association between short-term SES shift and long-term cardiovascular outcomes in China. Methods In participants who had completed China Kadoorie Biobank study resurvey, 18 672 were included in the final analysis after excluding those who had cardiovascular diseases at baseline, and those who had a cardiovascular event before the resurvey. We used education, occupation, household income and healthcare cover as measurement of SES, and generated SES class for each individual at baseline and resurvey using latent class analysis. Outcomes of interest included cardiovascular death, major coronary event (MCE) and stroke. We used accelerated failure time model to obtain survival time ratio for each level of SES shift. Results During a mean time gap of 2.6 years, 10 273 (55%) individuals remained stable in SES, 7763 (41.6%) shifted towards higher SES and 636 (3.4%) shifted towards lower SES. Participants were followed up for a mean of 9.8 years. After adjusting for baseline factors, sharp but not moderate SES downshift was significantly associated with shortened event-free survival time before cardiovascular deaths (p=0.02) and MCEs (p<0.001) occurred. Contrarily, moderate and sharp SES upshift was significantly associated with prolonged event-free survival time before cardiovascular deaths (p=0.0027 and p<0.001) and MCEs (p=0.0079 and p=0.009) occurred. Conclusion Short-term SES improvement is associated with better long-term cardiovascular outcome in China. High baseline SES might buffer out some unfavourable impact brought by moderate SES downshift. More comprehensive strategies should be considered in policy-making for socioeconomic development.