Aims: The aim of this report from a general population sample was to examine the association of respiratory symptoms and COPD severity with HRQoL (health related quality of life).
Methods: In a general population study in 1996-1997, of 3181 invited subjects aged 26-81 years, a total of 2405 returned postal questionnaires on respiratory symptoms and attended a clinical examination. Altogether 2306 subjects completed the SF-12 questionnaire, a general HRQoL questionnaire. The univariate relationships between respiratory symptom burden, degree of bronchial obstruction, and HRQoL were investigated by the Wilcoxon test for trend and the Mann-Whitney U-test. Adjustment for gender, age, education, and smoking habits was done using linear regression with estimation of robust standard errors.
Results: In asymptomatic subjects the mean (SD) physical component scale (PCS) score was 51.8 (7.4) and the mean (SD) mental component scale (MCS) score was 52.6 (8.0). Having one to six symptoms gave mean (SD) PCS scores of 49.6 (8.8), 48.2 (9.7), 45.1 (10.4), 42.1 (11.9), 38.1 (11.4), and 34.7 (10.2), respectively. The corresponding numbers for MCS scores were 50.9 (8.0), 48.8 (9.6), 48.9 (10.6), 47.2 (10.2), 43.6 (10.4), and 44.2 (9.8), respectively. In the multivariate model, subjects in GOLD stages 3 and 4 had significantly reduced PCS scores, while subjects with COPD had a significantly higher MCS score than subjects without COPD, after adjustment for symptoms. Both the PCS and MCS scores declined significantly with increasing number of respiratory symptoms.
Conclusion: In a general population sample, the burden of respiratory symptoms is more strongly associated with generic HRQoL than is lung function.