Impact of patient-related factors on asthma control

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 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.