title: Syndromic surveillance use to detect the early effects of heat-waves: an analysis of NHS direct data in England.
abstract: OBJECTIVE
  To investigate the effects of high ambient temperatures, including the summer 2003 heat-episode, on NHS Direct usage and its suitability as a surveillance tool in heat health warning systems.
  
  
  METHODS
  Analyses of data on calls to NHS Direct in English Regions in the period Dec 2001-May 2004. Outcomes were daily rates of all symptomatic calls, and daily proportion of calls for selected causes (fever, vomiting, difficulty breathing, heat/sun-stroke)
  
  
  RESULTS
  Total calls were moderately increased as environmental temperature increased; this effect was greatest in calls for young children and for fever. Total calls were moderately elevated during two summer heat episodes in 2003: calls specifically for heat/sun stroke increased acutely in response to these episodes. No association was apparent between environmental temperature and proportion of calls for vomiting and difficulty breathing.
  
  
  CONCLUSIONS
  Calls to NHS Direct are sensitive to daily temperatures and extreme weather. NHS Direct is timely and has great potential in health surveillance. Calls for heat- and sun-stroke are now routinely monitored as part of the UK Heat-wave plan
authors.affiliation: Health Protection Agency Chemical Hazards & Poisons Division (Headquarters), Oxon, Great Britain.
authors.forename: G S
authors.initials: GS
authors.lastname: Leonardi
authors.forename: S
authors.initials: S
authors.lastname: Hajat
authors.forename: R S
authors.initials: RS
authors.lastname: Kovats
authors.forename: G E
authors.initials: GE
authors.lastname: Smith
authors.forename: D
authors.initials: D
authors.lastname: Cooper
authors.forename: E
authors.initials: E
authors.lastname: Gerard
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000453:epidemiology; D004739:England; D005334:Fever / Q000453:epidemiology; D018883:Heat Stroke / Q000453:epidemiology; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D008131:London; D008875:Middle Aged; D011159:Population Surveillance; D013222:State Medicine / Q000706:statistics & numerical data*; D013474:Sunstroke / Q000453:epidemiology; D013696:Temperature; D014839:Vomiting / Q000453:epidemiology