title: Seasonal risk factors for asthma exacerbations among inner-city children.
abstract: BACKGROUND
  Asthma exacerbations remain common, even in children and adolescents, despite optimal medical management. Identification of host risk factors for exacerbations is incomplete, particularly for seasonal episodes.
  
  
  OBJECTIVE
  We sought to define host risk factors for asthma exacerbations unique to their season of occurrence.
  
  
  METHODS
  This is a retrospective analysis of patients aged 6 to 20 years who comprised the control groups of the Asthma Control Evaluation study and the Inner City Anti-IgE Therapy for Asthma study. Univariate and multivariate models were constructed to determine whether patients' demographic and historical factors, allergic sensitization, fraction of exhaled nitric oxide values, spirometric measurements, asthma control, and treatment requirements were associated with seasonal exacerbations.
  
  
  RESULTS
  The analysis included 400 patients (54.5% male; 59.0% African American; median age, 13 years). Exacerbations occurred in 37.5% of participants over the periods of observation and were most common in the fall (28.8% of participants). In univariate analysis impaired pulmonary function was significantly associated with greater odds of exacerbations for all seasons, as was an exacerbation in the previous season for all seasons except spring. In multivariate analysis exacerbation in the previous season was the strongest predictor in fall and winter, whereas a higher requirement for inhaled corticosteroids was the strongest predictor in spring and summer. The multivariate models had the best predictive power for fall exacerbations (30.5% variance attributed).
  
  
  CONCLUSIONS
  Among a large cohort of inner-city children with asthma, patients' risk factors for exacerbation vary by season. Thus information on individual patients might be beneficial in strategies to prevent these seasonal events.
authors: Children's National Health System and the George Washington University School of Medicine and Health Sciences, Washington, DC. Electronic address: steach@childrensnational.org.
authors: Stephen J
authors: SJ
authors: Teach
authors: National Institute of Allergy and Infectious Diseases, Bethesda, Md.
authors: Peter J
authors: PJ
authors: Gergen
authors: Children's Hospital Colorado and University of Colorado Denver School of Medicine, Aurora, Colo.
authors: Stanley J
authors: SJ
authors: Szefler
authors: Rho Federal Systems Division, Chapel Hill, NC.
authors: Herman E
authors: HE
authors: Mitchell
authors: Rho Federal Systems Division, Chapel Hill, NC.
authors: Agustin
authors: A
authors: Calatroni
authors: Rho Federal Systems Division, Chapel Hill, NC.
authors: Jeremy
authors: J
authors: Wildfire
authors: Washington University School of Medicine, St Louis, Mo.
authors: Gordon R
authors: GR
authors: Bloomberg
authors: Cincinnati Children's Hospital, Cincinnati, Ohio.
authors: Carolyn M
authors: CM
authors: Kercsmar
authors: National Jewish Health, Denver, and Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, Colo.
authors: Andrew H
authors: AH
authors: Liu
authors: Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Ill.
authors: Melanie M
authors: MM
authors: Makhija
authors: Johns Hopkins University School of Medicine, Baltimore, Md.
authors: Elizabeth
authors: E
authors: Matsui
authors: University of Arizona College of Medicine, Tucson, Ariz.
authors: Wayne
authors: W
authors: Morgan
authors: Boston University School of Medicine, Boston, Mass.
authors: George
authors: G
authors: O'Connor
authors: University of Wisconsin School of Medicine and Public Health, Madison, Wis.
authors: William W
authors: WW
authors: Busse
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D001741:Black or African American; D000704:Analysis of Variance; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy* / Q000208:ethnology / Q000503:physiopathology; D002648:Child; D018450:Disease Progression; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D044465:White People; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D018927:Anti-Asthmatic Agents; D009569:Nitric Oxide; D007073:Immunoglobulin E
keywords: Asthma; IgE; allergy; asthma exacerbations; biomarkers; eosinophils; exhaled nitric oxide; pulmonary function; seasons