Effect of spirometry and medical review on asthma control in patients in general practice: a randomized controlled trial.

BACKGROUND AND OBJECTIVE: Although guidelines for asthma emphasize the importance of spirometry for continuity and evaluation of care, it is underused in general practice. The objective of this study was to investigate the effect of spirometry and medical review on asthma control in general practice over 12 months. METHODS: Patients were recruited through 31 practices, which were randomly allocated to one of three groups: Group A had 3-monthly spirometry with medical review, Group B spirometry only before and after the trial, and Group C usual care. Asthma control data were analysed by intention to treat using non-parametric tests and logistic regression models fitted to allow for confounders, repeated measures and clustering by practice. RESULTS: The trial was completed by 195 patients (Group A 69, Group B 78, Group C 48). Asthma control improved in all groups during the 12 months trial, most impressively in Group A (odds ratio per 3 months = 1.27, 95% confidence interval: 1.08-1.49, P = 0.004), but the difference between the groups' respective 3-monthly changes was not significant. At 6 months, asthma control in Group A had increased more from baseline than in Groups B + C (P = 0.006). CONCLUSIONS: Regular spirometry with medical review was associated with improved asthma control in general practice patients, while there was less improvement in either the spirometry only or usual care group. The mechanisms of this improvement may include appropriate adjustment of medication and improved compliance.