title: Cold spells and the risk of hospitalization for asthma: New York, USA 1991-2006.
abstract: OBJECTIVE
  A study was conducted to investigate whether prolonged periods of very cold temperatures were associated with an increased risk of hospitalization for asthma.
  
  
  METHODS
  Hospitalization admissions with a principal diagnosis of asthma were identified in New York State, USA, for the months November through April from 1991 to 2006. A cold spell was defined as three or more consecutive days where the daily mean of universal apparent temperature (UAT) within a week prior to admission was at the 10th percentile or less. The percentage change in asthma hospitalizations during and after a cold spell was compared to the average daily number of hospitalizations preceding the cold spell using time series analysis.
  
  
  RESULTS
  The average temperature during winter cold spells (December through March) was -15 °C, compared to -6 and -2 °C for cold spells in November and April, respectively. Cold spells during the winter months were associated with a mean decline of 4.9 % in asthma admissions statewide (95 % CI -7.8, -1.9 %). After a cold spell, no statistically significant changes were apparent during the winter months, but asthma hospitalizations increased after cold spells in the transitional months of November (mean = 9.6, 95 % CI 5.5, 13.9 %) and April (mean = 5.0, 95 % CI 1.2, 9.0 %).
  
  
  CONCLUSIONS
  The results suggest that during prolonged periods of severe cold asthmatics may adhere to medical guidelines and limit their exposure, thereby preventing exacerbations. They may be less likely to alter their behavior in the more moderate months of November and April.
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University at Albany, State University of New York, 1 University Place, Rensselaer, NY, 12144, USA, Efitzgerald@albany.edu.
authors.forename: Edward F
authors.initials: EF
authors.lastname: Fitzgerald
authors.forename: Cristian
authors.initials: C
authors.lastname: Pantea
authors.forename: Shao
authors.initials: S
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology*; D002648:Child; D003080:Cold Temperature / Q000009:adverse effects*; D016001:Confidence Intervals; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009518:New York; D010343:Patient Admission / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment; D012621:Seasons; D017678:Sex Distribution; D013997:Time Factors; D055815:Young Adult