Objective To quantify the lagged effects of mean temperature on deaths from cardiovascular diseases in Brisbane, Australia.
Design Polynomial distributed lag models were used to assess the percentage increase in mortality up to 30 days associated with an increase (or decrease) of 1°C above (or below) the threshold temperature.
Setting Brisbane, Australia.
Patients 22 805 cardiovascular deaths registered between 1996 and 2004.
Main outcome measures Deaths from cardiovascular diseases.
Results The results show a longer lagged effect in cold days and a shorter lagged effect in hot days. For the hot effect, a statistically significant association was observed only for lag 0–1 days. The percentage increase in mortality was found to be 3.7% (95% CI 0.4% to 7.1%) for people aged ≥65 years and 3.5% (95% CI 0.4% to 6.7%) for all ages associated with an increase of 1°C above the threshold temperature of 24°C. For the cold effect, a significant effect of temperature was found for 10–15 lag days. The percentage estimates for older people and all ages were 3.1% (95% CI 0.7% to 5.7%) and 2.8% (95% CI 0.5% to 5.1%), respectively, with a decrease of 1°C below the threshold temperature of 24°C.
Conclusions The lagged effects lasted longer for cold temperatures but were apparently shorter for hot temperatures. There was no substantial difference in the lag effect of temperature on mortality between all ages and those aged ≥65 years in Brisbane, Australia.
- Cardiovascular deaths
- lagged effect
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Funding This work was partly supported by an Australian Research Council Discovery grant (#559655). ST was supported by an NHMRC Research Fellowship (#553043) and WY was supported by a Queensland University of Technology scholarship.
Competing interests None.
Ethics approval This study was conducted with the approval of the Queensland University of Technology ethical committee.
Provenance and peer review Not commissioned; externally peer reviewed.