title: Measures of asthma control and quality of life: longitudinal data provide practical insights into their relative usefulness in different research contexts.
abstract: OBJECTIVE
  To further our understanding of the relationships between asthma control and health-related quality of life (HRQOL) and provide insights into the relative usefulness of various measures in different research contexts. We present a conceptual model and test it with longitudinal survey data.
  
  
  METHODS
  Participants recruited via population sampling and hospital Emergency Departments completed questionnaires every 6 months for up to 3 years. Measures included: sleep disturbance, use of short-acting beta agonists (SABA), activity limitation, urgent medical visits, hospital use, Marks' Asthma Quality of Life Questionnaire (AQLQ-M) and the SF-36 Health Survey. Correlation analysis and multi-level models tested predictions from the conceptual model.
  
  
  RESULTS
  A total of 213 people with asthma aged 16-75 years provided 967 observations. Correlations between asthma control and asthma-specific HRQOL were stronger than those between asthma control and generic HRQOL. The asthma control variables explained 54-58% of the variance in asthma-specific HRQOL and 8-25% of the variance in generic HRQOL. Activity limitation was the main contributor to between-person variation, while sleep disturbance and SABA use were the main contributors to within-person variation.
  
  
  CONCLUSIONS
  Sleep disturbance and SABA use may be most useful in evaluating treatment effectiveness, while activity limitation may be better when monitoring the impact of asthma in populations.
authors.affiliation: Quality of Life Office, Psycho-oncology Co-operative Research Group (PoCoG), School of Psychology, University of Sydney, Brennan MacCallum Building (A18), Sydney, 2006, NSW, Australia. mking@psych.usyd.edu.au
authors.forename: Madeleine T
authors.initials: MT
authors.lastname: King
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Kenny
authors.forename: Guy B
authors.initials: GB
authors.lastname: Marks
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D011795:Surveys and Questionnaires; D055815:Young Adult