title: Association of mortality with high temperatures in a temperate climate: England and Wales.
abstract: BACKGROUND
  It is well known that high ambient temperatures are associated with increased mortality, even in temperate climates, but some important details are unclear. In particular, how heat-mortality associations (for example, slopes and thresholds) vary by climate has previously been considered only qualitatively.
  
  
  METHODS
  An ecological time-series regression analysis of daily counts of all-cause mortality and ambient temperature in summers between 1993 and 2006 in the 10 government regions was carried out, focusing on all-cause mortality and 2-day mean temperature (lags 0 and 1).
  
  
  RESULTS
  All regions showed evidence of increased risk on the hottest days, but the specifics, in particular the threshold temperature at which adverse effects started, varied. Thresholds were at about the same centile temperatures (the 93rd, year-round) in all regions-hotter climates had higher threshold temperatures. Mean supra-threshold slope was 2.1%/°C (95% CI 1.6 to 2.6), but regions with higher summer temperatures showed greater slopes, a pattern well characterised by a linear model with mean summer temperature. These climate-based linear-threshold models capture most, but not all, the association; there was evidence for some non-linearity above thresholds, with slope increasing at highest temperatures.
  
  
  CONCLUSIONS
  Effects of high daily summer temperatures on mortality in English regions are quite well approximated by threshold-linear models that can be predicted from the region's climate (93rd centile and mean summer temperature). It remains to be seen whether similar relationships fit other countries and climates or change over time, such as with climate change.
authors.affiliation: London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK. ben.armstrong@lshtm.ac.uk
authors.forename: B G
authors.initials: BG
authors.lastname: Armstrong
authors.forename: Z
authors.initials: Z
authors.lastname: Chalabi
authors.forename: B
authors.initials: B
authors.lastname: Fenn
authors.forename: S
authors.initials: S
authors.lastname: Hajat
authors.forename: S
authors.initials: S
authors.lastname: Kovats
authors.forename: A
authors.initials: A
authors.lastname: Milojevic
authors.forename: P
authors.initials: P
authors.lastname: Wilkinson
mesh_terms: D004739:England / Q000453:epidemiology; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D015233:Models, Statistical; D009026:Mortality / Q000639:trends*; D012044:Regression Analysis; D018570:Risk Assessment; D014852:Wales / Q000453:epidemiology