Factors affecting adherence to asthma treatment in an international cohort of young and middle-aged adults

BACKGROUND: A major reason of the poor control of asthma is that patients fail to adhere to their treatment. The aim of the study was to identify factors affecting changes in asthma treatment adherence in an international cohort. METHODS: A follow-up study was carried out by means of a structured clinical interview in 971 subjects with asthma from 12 countries who participated in both the European Community Respiratory Health Survey: ECRHS-I (1990-94) and ECRHS-II (1998-2002). Subjects were considered adherent if they reported they normally took all the prescribed drugs. A logistic model was used to study the adjusted effect of the determinants. RESULTS: The net change in adherence to anti-asthmatic treatment per 10 years of follow-up was -2% (95% CI: -9.5, 5.5), 7.5% (-2.6, 17.6), 15.0% (6.6, 23.5) and 19.8% (4.1, 35.5), respectively, in Nordic, Mediterranean, Continental and extra-European areas. Among the 428 non-adherent subjects in ECRHS-I, having regular consultations with health care professionals was the strongest predictor of increased adherence (OR 3.32; 95% CI: 1.08-10.17). Among the 543 adherent subjects in ECRHS-I, using inhaled corticosteroids significantly predicted a persistence of adherence (OR 2.04; 95% CI: 1.11-3.75). No effect of gender, age, duration of the disease, smoking habit and educational level was observed. CONCLUSIONS: Our findings highlight the key role of doctors and nurses in educating and regularly reviewing the patients and support the efforts for an improvement of clinical communication.