Background: Patient-related factors are a significant component in the serious public health problem of poor asthma control, yet they have not been extensively studied.
Aims: To gauge the impact of baseline patient characteristics, compliance and inhaler device manipulation on Asthma Control Score (ACS).
Methods: ACS (between 0 and 9) was calculated from data recorded in a routine consultation in 4,362 patients with persistent asthma using a maintenance treatment with only inhaled corticosteroid and correlated with patient characteristics, compliance (using 2 methods) and critical errors in inhaler handling.
Results: Mean ASC was 2.95 (95%CI: 2.88-3.02) and asthma control was unsatisfactory (i.e., ACS > or = 4) in 41.1% of subjects, with higher proportions in smokers, non-compliant patients, and those misusing their device. Mean ACS tended to rise with age, and was higher in smokers than in non-smokers (+0.83 point) and ex-smokers (+0.49 point). More than 20% of all subjects were using their inhaler device incorrectly (Turbuhaler 37.1%; Metered-dose inhaler 28.1%; Diskus 21.3%; Aerolizer 7.4%) and this was associated with a 0.84-point increase in ACS. Mean ACS was lower in the most compliant patients (-0.74 points in the 13.4% with a perfect score on a compliance questionnaire) and much lower than in the least compliant (-1.84 points in the 6.6% who reported missing 4 or more doses per week).
Conclusion: Patient-related factors including smoking, poor compliance and critical errors in device manipulation, have significant negative impact on asthma control. This could be addressed by patient education.