Document Detail

Heat and risk of myocardial infarction: hourly level case-crossover analysis of MINAP database.
MedLine Citation:
PMID:  23243290     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To quantify the association between exposure to higher temperatures and the risk of myocardial infarction at an hourly temporal resolution.
DESIGN: Case-crossover study.
SETTING: England and Wales Myocardial Ischaemia National Audit Project (MINAP) database.
PARTICIPANTS: 24,861 hospital admissions for myocardial infarction occurring in 11 conurbations during the warmest months (June to August) of the years 2003-09.
MAIN OUTCOME MEASURE: Odds ratio of myocardial infarction for a 1 °C increase in temperature.
RESULTS: Strong evidence was found for an effect of heat acting 1-6 hours after exposure to temperatures above an estimated threshold of 20 °C (95% confidence interval 16 °C to 25 °C). For each 1 °C increase in temperature above this threshold, the risk of myocardial infarction increased by 1.9% (0.5% to 3.3%, P=0.009). Later reductions in risk seemed to offset early increases in risk: the cumulative effect of a 1 °C rise in temperature above the threshold was 0.2% (-2.1% to 2.5%) by the end of the third day after exposure.
CONCLUSIONS: Higher ambient temperatures above a threshold of 20 °C seem to be associated with a transiently increased risk of myocardial infarction 1-6 hours after exposure. Reductions in risk at longer lags are consistent with heat triggering myocardial infarctions early in highly vulnerable people who would otherwise have had a myocardial infarction some time later ("short term displacement"). Policies aimed at reducing the health effects of hot weather should include consideration of effects operating at sub-daily timescales.
Krishnan Bhaskaran; Ben Armstrong; Shakoor Hajat; Andy Haines; Paul Wilkinson; Liam Smeeth
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-12-13
Journal Detail:
Title:  BMJ (Clinical research ed.)     Volume:  345     ISSN:  1756-1833     ISO Abbreviation:  BMJ     Publication Date:  2012  
Date Detail:
Created Date:  2012-12-17     Completed Date:  2013-02-13     Revised Date:  2014-03-19    
Medline Journal Info:
Nlm Unique ID:  8900488     Medline TA:  BMJ     Country:  England    
Other Details:
Languages:  eng     Pagination:  e8050     Citation Subset:  AIM; IM    
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MeSH Terms
Aged, 80 and over
Case-Control Studies
Confidence Intervals
Cross-Over Studies
England / epidemiology
Hot Temperature / adverse effects*
Middle Aged
Myocardial Infarction / epidemiology*,  etiology
Odds Ratio
Risk Factors
Time Factors
Wales / epidemiology
Young Adult
Grant Support
086091/Z/08/Z//Wellcome Trust; 098504//Wellcome Trust; 098504/Z/12/Z//British Heart Foundation; FS/04/045//British Heart Foundation; PDF-2011-04-007//Department of Health

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