title: Validation of the Asthma Predictive Index and comparison with simpler clinical prediction rules.
abstract: BACKGROUND
  The loose and stringent Asthma Predictive Indices (API), developed in Tucson, are popular rules to predict asthma in preschool children. To be clinically useful, they require validation in different settings.
  
  
  OBJECTIVE
  To assess the predictive performance of the API in an independent population and compare it with simpler rules based only on preschool wheeze.
  
  
  METHODS
  We studied 1954 children of the population-based Leicester Respiratory Cohort, followed up from age 1 to 10 years. The API and frequency of wheeze were assessed at age 3 years, and we determined their association with asthma at ages 7 and 10 years by using logistic regression. We computed test characteristics and measures of predictive performance to validate the API and compare it with simpler rules.
  
  
  RESULTS
  The ability of the API to predict asthma in Leicester was comparable to Tucson: for the loose API, odds ratios for asthma at age 7 years were 5.2 in Leicester (5.5 in Tucson), and positive predictive values were 26% (26%). For the stringent API, these values were 8.2 (9.8) and 40% (48%). For the simpler rule early wheeze, corresponding values were 5.4 and 21%; for early frequent wheeze, 6.7 and 36%. The discriminative ability of all prediction rules was moderate (c statistic ≤ 0.7) and overall predictive performance low (scaled Brier score < 20%).
  
  
  CONCLUSIONS
  Predictive performance of the API in Leicester, although comparable to the original study, was modest and similar to prediction based only on preschool wheeze. This highlights the need for better prediction rules.
authors: Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors: Nora A
authors: NA
authors: Leonardi
authors: Ben D
authors: BD
authors: Spycher
authors: Marie-Pierre F
authors: MP
authors: Strippoli
authors: Urs
authors: U
authors: Frey
authors: Michael
authors: M
authors: Silverman
authors: Claudia E
authors: CE
authors: Kuehni
mesh_terms: D000293:Adolescent; D001130:Arizona; D001249:Asthma / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004198:Disease Susceptibility; D004739:England; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012135:Respiratory Sounds / Q000503:physiopathology; D011795:Surveys and Questionnaires