Factors associated with health-related quality of life in adults with asthma. A cross-sectional study

Background: The measurement of health-related quality of life (HRQoL) is increasingly recognized as an important endpoint, as a reflection of the effects of the disease from a patient perspective. Our aim was to evaluate the factors determining the HRQoL in patients with asthma, according to the EQ-5D questionnaire. Methods: Patients were included using multi-stage sampling, from Primary Care clinics from all the Autonomous Communities in Spain. The patients included were: over 18 years-old, with a confirmed diagnosis of asthma for at least one year, and had visited a Health Centre in the previous 2 years. The characteristics of the asthma disease, the adherence to treatment, the socio-demographic variables, the smoking habits, and the asthma control were collected using a questionnaire. The influence of the different variables included in the study on the EQ-5D was evaluated using multivariate logistic regression analysis. Results: A total of 2,125 patients were finally included (57.7% females, mean age 48 years). The response rate was 95.4%. Some factors showed a considerable detrimental effect on the HRQoL of asthmatics. Advanced age, lower educational level and poor control of asthma are significantly associated with a worse quality of life in all the dimensions assessed by the EQ-5D scale. The baseline severity of the asthma, and having been admitted to hospital are related to a worse quality of life in 5 of the 6 dimensions analyzed. Conclusion: In our study, we could identify some factors related to quality of life in asthma patients. The most important were advanced age, lower education level, and poor control of the asthma.