Associations between short-term PM2.5 exposure and major cardiovascular events in high-risk population: a nationwide case-crossover study.

OBJECTIVES

While particulate matter with a diameter ≤2.5 µm (PM2.5) is a recognised major modifiable risk factor with well-documented short-term impacts on acute cardiovascular events in the general population, data regarding its effects on high-risk populations with significant atherosclerotic risk are limited. This study aims to identify the association between short-term exposure to PM2.5 and acute major cardiovascular events in Thailand.

DESIGN

A time-stratified case-crossover design.

SETTING

The nationwide Cohort Of patients with high Risk for cardiovascular Events-Thailand registry (CORE-Thailand registry).

PARTICIPANTS

A total of 1121 individuals from the registry who experienced four-point major adverse cardiovascular events (4P-MACEs) between 2011 and 2019.

PRIMARY OUTCOME MEASURE: The primary exposure was defined as short-term PM2.5 exposure, with the primary outcome being a first-time MACE, which included acute myocardial infarction, stroke, heart failure hospitalisation and all-cause death.

METHODS

Using a time-stratified case-crossover design, the analysed events included non-fatal myocardial infarction, non-fatal stroke, heart failure hospitalisation and all-cause death. Daily PM2.5 concentrations during the event and control periods were obtained from nearby air quality monitors. Conditional logistic regression models assessed odds ratio (ORs) for 4P-MACE per 10 µg/m³ increase in PM2.5 exposure over lag periods from 0 to 7 days.

RESULTS

The participants had a mean age of 69.9 years and 55.8% were male. Most had pre-existing atherosclerotic cardiovascular diseases (74.6%), diabetes mellitus (58.4%), hypertension (98.1%) and dyslipidaemia (83.3%). Significant associations were observed for both single-day (lag 1 to lag 4) and average-days (lag 01 to 07) PM2.5 exposures. A 10 µg/m³ increase in PM2.5 was associated with increased odds of MACEs, with ORs of 1.06 (95% CI 1.01 - 1.11) for single-day lagged exposures and varying ORs from 1.06 to 1.08 for average-days lagged exposures (lags 01 to 04).

CONCLUSIONS

Short-term PM2.5 exposure significantly increased the risk of MACE in the Thai population with high atherosclerotic risk. These findings underscore the urgency of public health interventions aimed at mitigating air pollution exposure, especially among vulnerable groups.

TRIAL REGISTRATION: The study is registered with the Thai Clinical Trials Registry (TCTR20130520001).