Determinants of uncontrolled asthma in a Swedish asthma population: cross-sectional observational study

BACKGROUND: Asthma control is achieved in a low proportion of patients. The primary aim was to evaluate risk factors for uncontrolled asthma. The secondary aim was to assess quality of life associated with asthma control. METHODS: In a cross-sectional study, asthma patients aged 18–75 were randomly selected from primary and secondary health care centers. Postal questionnaires were sent to 1,675 patients and the response rate was 71%. A total of 846 patients from primary and 341 patients from secondary care were evaluated. Data were collected using a questionnaire and review of medical records. The questionnaire included questions about asthma control and a quality-of-life questionnaire, the mini-AQLQ, with four domains (symptoms, activity limitation, emotional function, and environmental stimuli). The mean score for each domain and the overall score were calculated. Asthma control was divided into three levels according to the GINA guidelines and partly and uncontrolled asthma were combined into one group – poorly controlled asthma. RESULTS: Asthma control was achieved in 36% of the sample: 38% in primary and 29% in secondary care. In primary and secondary care, 35 and 45% had uncontrolled asthma, respectively. Risk factors for poorly controlled asthma were female sex [OR 1.31 (1.003–1.70)], older age [OR 2.18 (1.28–3.73)], lower educational level [OR 1.63 (1.14–2.33)], and current smoking [OR 1.68 (1.16–2.43)]. Older age and lower educational level remained statistically significantly associated with poorly controlled asthma when the analyses were limited to never-smokers. Depression was an independent risk factor for poorly controlled asthma in men [OR 3.44 (1.12–10.54)]. The mini-AQLQ scores and the mean overall score were significantly lower in uncontrolled asthma. CONCLUSION: Risk factors for poorly controlled asthma were female sex, older age, low educational level, and smoking. Uncontrolled asthma was significantly associated with lower quality of life.