Short - term effects of temperature on hospital admissions for acute myocardial infarction: A comparison between two neighboring climate zones in Vietnam

Background: Vietnam is one of the countries most affected by climate change, but few studies have focused on the population health effects of climate variation. Extreme heatwaves and cold spells might exacerbate underlying chronic conditions and precipitate hospitalization or early death. This study examined the short-term effects of ambient temperature extremes on hospital admissions (HAs) due to acute myocardial infarction (AMI) between different climate zones in the Central Coast region of Vietnam. Methods: Information from medical records of all 3328 cases of AMI HAs (with hospital records cross-checked by clinicians) was collected from three hospitals in the South-Central Coast region (tropical savanna climate) and North-Central Coast region (tropical monsoon climate) for the period 2008–2015. Meteorological data were obtained from the National Hydro-Meteorological and Environment Network Centre. We used distributed lag non-linear models to assess the association between daily average temperature and AMI HAs, accounting for long-term trend and other meteorological variables. Results: We found a negative and significant association between AMI HAs and temperature in the North-Central Coast region while conversely there was a positive and significant association in the South-Central Coast region. In the North-Central Coast region, the risk of AMI HAs increased by 11% (Relative risk (RR): 1.11, 95% CI: 0.91–1.35, p > 0.05) at moderately low temperatures (10th percentile of temperature range – 18.5 °C) and increased by 25% (RR: 1.25, 95% CI: 1.02–1.55, p < 0.05) at extremely low temperatures (5th percentile of temperature range – 16.8 °C). In the South-Central Coast region, the risk of AMI HAs increased by 18% (RR: 1.18, 95% CI: 0.95–1.47, p > 0.05) and 36% (RR: 1.36, 95% CI: 1.06–1.73, p < 0.05) at moderately high temperatures (90^th percentile of temperature range −29.5 °C) and extreme high temperatures (95th percentile of temperature range – 29.9 °C), respectively. Conclusions: Risk of AMI is associated with extremely high and extremely low temperature in Vietnam and the risk varies in relation to the local regional climate. Public health preparedness and multi-level interventions should attempt to reduce people's exposure in periods of disadvantageous temperatures.