title: Forced expiratory volume in 1 second percentage improves the classification of severity among children with asthma.
abstract: OBJECTIVE
  Spirometry is an important component of the National Asthma Education and Prevention Program guidelines for asthma, yet published data show variable associations between forced expiratory volume in 1 second percentage (FEV1%) predicted, symptoms and health care utilization. The objective of this analysis was to examine the association between FEV1% and future risk of exacerbations among a well-characterized population of children with asthma.
  
  
  METHODS
  Using data that are available from the Childhood Asthma Management Program, we examined the relationship between prebronchodilator FEV1% and important clinical outcomes. Multiple observations of FEV1 were available for each patient; multivariate regression analysis, using a general estimating equation approach, was used to control for the correlation between repeated measurements among individuals and potential confounders. FEV1% was categorized into 4 levels and as a continuous variable. Outcomes of interest included mean symptom score (0-3), episode-free days, and asthma-related events (oral steroid use, emergency department visits, and hospitalizations) during the ensuing 4-month period. Our analysis was limited to the placebo group (N = 417).
  
  
  RESULTS
  We observed a clear relationship between prebronchodilator FEV1% and important clinical outcomes. In multivariable models that simultaneously controlled for covariates of interest, age at baseline, time, previous event history, and nocturnal awakenings, a significant relationship between FEV1% and asthma symptoms and serious asthma exacerbations (oral steroids, emergency department visits, and hospitalizations) was observed. Compared with children with an FEV1% > or = 100%, children with FEV1% 80% to 99%, 60% to 79%, and < 60% were 1.3, 1.8, and 4.8, respectively, more likely to have a serious asthma exacerbation during the ensuing 4 months. CONCLUSIONS. In children with mild to moderate asthma, FEV1% predicted is independently associated with future asthma symptoms and health care utilization. Previous asthma-related hospitalizations and nocturnal symptoms also were independently associated with risk for future adverse events. FEV1 is an important component of asthma health status and asthma severity classification.
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. anne.fuhlbrigge@channing.harvard.edu
authors.forename: Anne L
authors.initials: AL
authors.lastname: Fuhlbrigge
authors.forename: Scott T
authors.initials: ST
authors.lastname: Weiss
authors.forename: Karen M
authors.initials: KM
authors.lastname: Kuntz
authors.forename: A David
authors.initials: AD
authors.lastname: Paltiel
mesh_terms: D000420:Albuterol / Q000627:therapeutic use; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000145:classification* / Q000188:drug therapy / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D001993:Bronchodilator Agents / Q000627:therapeutic use; D019819:Budesonide / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004311:Double-Blind Method; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008962:Models, Theoretical; D015337:Multicenter Studies as Topic; D017835:Nedocromil / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D012720:Severity of Illness Index; D013147:Spirometry; D016896:Treatment Outcome
chemical_list: D018927:Anti-Asthmatic Agents; D001993:Bronchodilator Agents; D017835:Nedocromil; D016210:Methacholine Chloride; D019819:Budesonide; D000420:Albuterol