title: Evaluation of a heat vulnerability index on abnormally hot days: an environmental public health tracking study.
abstract: BACKGROUND
  Extreme hot weather conditions have been associated with increased morbidity and mortality, but risks are not evenly distributed throughout the population. Previously, a heat vulnerability index (HVI) was created to geographically locate populations with increased vulnerability to heat in metropolitan areas throughout the United States.
  
  
  OBJECTIVE
  We sought to determine whether areas with higher heat vulnerability, as characterized by the HVI, experienced higher rates of morbidity and mortality on abnormally hot days.
  
  
  METHODS
  We used Poisson regression to model the interaction of HVI and deviant days (days whose deviation of maximum temperature from the 30-year normal maximum temperature is at or above the 95th percentile) on hospitalization and mortality counts in five states participating in the Environmental Public Health Tracking Network for the years 2000 through 2007.
  
  
  RESULTS
  The HVI was associated with higher hospitalization and mortality rates in all states on both normal days and deviant days. However, associations were significantly stronger (interaction p-value < 0.05) on deviant days for heat-related illness, acute renal failure, electrolyte imbalance, and nephritis in California, heat-related illness in Washington, all-cause mortality in New Mexico, and respiratory hospitalizations in Massachusetts.
  
  
  CONCLUSIONS
  Our results suggest that the HVI may be a marker of health vulnerability in general, although it may indicate greater vulnerability to heat in some cases.
authors.affiliation: Environmental Health Sciences, School of Public Health, University of California-Berkeley, Berkeley, California 94720-7360, USA. creid@berkeley.edu
authors.forename: Colleen E
authors.initials: CE
authors.lastname: Reid
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Mann
authors.forename: Ruth
authors.initials: R
authors.lastname: Alfasso
authors.forename: Paul B
authors.initials: PB
authors.lastname: English
authors.forename: Galatea C
authors.initials: GC
authors.lastname: King
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Lincoln
authors.forename: Helene G
authors.initials: HG
authors.lastname: Margolis
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Rubado
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Sabato
authors.forename: Nancy L
authors.initials: NL
authors.lastname: West
authors.forename: Brian
authors.initials: B
authors.lastname: Woods
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Navarro
authors.forename: John R
authors.initials: JR
authors.lastname: Balmes
mesh_terms: D002980:Climate; D004198:Disease Susceptibility; D004782:Environmental Health; D006359:Heat Exhaustion / Q000453:epidemiology*; D006358:Hot Temperature; D006801:Humans; D011634:Public Health; D014481:United States / Q000453:epidemiology