title: Ambient temperature and cardiorespiratory morbidity: a systematic review and meta-analysis.
abstract: BACKGROUND
  The effect of extreme temperature has become an increasing public health concern. Evaluating the impact of ambient temperature on morbidity has received less attention than its impact on mortality.
  
  
  METHODS
  We performed a systematic literature review and extracted quantitative estimates of the effects of hot temperatures on cardiorespiratory morbidity. There were too few studies on effects of cold temperatures to warrant a summary. Pooled estimates of effects of heat were calculated using a Bayesian hierarchical approach that allowed multiple results to be included from the same study, particularly results at different latitudes and with varying lagged effects.
  
  
  RESULTS
  Twenty-one studies were included in the final meta-analysis. The pooled results suggest an increase of 3.2% (95% posterior interval = -3.2% to 10.1%) in respiratory morbidity with 1°C increase on hot days. No apparent association was observed for cardiovascular morbidity (-0.5% [-3.0% to 2.1%]). The length of lags had inconsistent effects on the risk of respiratory and cardiovascular morbidity, whereas latitude had little effect on either.
  
  
  CONCLUSIONS
  The effects of temperature on cardiorespiratory morbidity seemed to be smaller and more variable than previous findings related to mortality.
authors.affiliation: School of Public Health and Social Work, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
authors.forename: Lyle R
authors.initials: LR
authors.lastname: Turner
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Barnett
authors.forename: Des
authors.initials: D
authors.lastname: Connell
authors.forename: Shilu
authors.initials: S
authors.lastname: Tong
mesh_terms: D001499:Bayes Theorem; D002318:Cardiovascular Diseases / Q000209:etiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D012140:Respiratory Tract Diseases / Q000209:etiology*