title: Assessing productivity loss and activity impairment in severe or difficult-to-treat asthma.
abstract: OBJECTIVE
  Asthma can be associated with substantial productivity loss and activity impairment, particularly among those with the most severe disease. We sought to assess the performance characteristics of an asthma-specific adaptation of the Work Productivity and Activity Impairment Questionnaire (WPAI:Asthma) in patients with either severe or difficult-to-treat asthma.
  
  
  METHODS
  We analyzed 2529 subjects from The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR) study. The WPAI:Asthma was administered at baseline and at 12 months. Asthma control and quality-of-life were simultaneously assessed using the Asthma Therapy Assessment Questionnaire and Mini-Asthma Quality-of-Life Questionnaire, respectively.
  
  
  RESULTS
  Severe versus mild-to-moderate asthma was associated with a greater percentage of impairment at work (28% vs. 14%), at school (32% vs. 18%), and in daily activities (41% vs. 21%). At baseline, greater asthma control problems correlated with higher levels of impairment as measured by the WPAI (work: r = 0.54, school: r = 0.37, activity: r = 0.55). Over the 12-month follow-up period, improved quality-of-life correlated with decreased levels of impairment (work: r = -0.42, school: r = -0.36, activity: r = -0.48). In multivariate analyses, greater than 10% overall work impairment at baseline predicted emergency visits (OR 2.6 [1.6, 4.0]) and hospitalization (OR 4.9 [1.8, 13.1]) at 12 months.
  
  
  CONCLUSIONS
  The WPAI:Asthma correlates with other self-reported asthma outcomes in the expected manner and predicts health-care utilization at 12 months when administered to patients with severe or difficult-to-treat asthma.
authors.affiliation: Department of Medicine, University of California, San Francisco, CA, USA, and Genentech Inc., South San Francisco, CA, USA. hubert.chen@ucsf.edu
authors.forename: Hubert
authors.initials: H
authors.lastname: Chen
authors.forename: Paul D
authors.initials: PD
authors.lastname: Blanc
authors.forename: Mary L
authors.initials: ML
authors.lastname: Hayden
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Bleecker
authors.forename: Anita
authors.initials: A
authors.lastname: Chawla
authors.forename: June H
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000041:Absenteeism; D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000191:economics*; D004526:Efficiency; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D018582:Sick Leave / Q000191:economics*; D017211:Treatment Failure
chemical_list: D018927:Anti-Asthmatic Agents