Background: Respiratory symptoms are common in the general population, and their presence is related to Health-related quality of life (HRQoL). The objective was to describe the association of respiratory symptoms with HRQoL in subjects with and without asthma or COPD and to investigate the role of atopy, bronchial hyperresponsiveness (BHR), and lung function in HRQoL.
Methods: The European Community Respiratory Health Survey (ECRHS) I and II provided data on HRQoL, lung function, respiratory symptoms, asthma, atopy, and BHR from 6009 subjects. Generic HRQoL was assessed through the physical component summary (PCS) score and the mental component summary (MCS) score of the SF-36. Factor analyses and linear regressions adjusted for age, gender, smoking, occupation, BMI, comorbidity, and study centre were conducted.
Results: Having breathlessness at rest in ECRHS II was associated with mean score (95% CI) impairment in PCS of -8.05 (-11.18, -4.93). Impairment in MCS score in subjects waking up with chest tightness was -4.02 (-5.51, -2.52). The magnitude of HRQoL impairment associated with respiratory symptoms was similar for subjects with and without asthma/COPD. Adjustments for atopy, BHR, and lung function did not explain the association of respiratory symptoms and HRQoL in subjects without asthma and/or COPD.
Conclusion: Subjects with respiratory symptoms had poorer HRQoL; including subjects without a diagnosis of asthma or COPD. These findings suggest that respiratory symptoms in the absence of a medical diagnosis of asthma or COPD are by no means trivial, and that clarifying the nature and natural history of respiratory symptoms is a relevant challenge.
Several community studies have estimated the prevalence of common respiratory symptoms like cough, dyspnoea, and wheeze in adults [1-3]. Although the prevalence varies to a large degree between studies and geographical areas, respiratory symptoms are quite common. The prevalences of respiratory symptoms in the European Community Respiratory Health Study (ECRHS) varied from one percent to 35% . In fact, two studies have reported that more than half of the adult population suffers from one or more respiratory symptoms [4,5].
Respiratory symptoms are important markers of the risk of having or developing disease. Respiratory symptoms have been shown to be predictors for lung function decline [6-8], asthma [9,10], and even all-cause mortality in a general population study . In patients with a known diagnosis of asthma or chronic obstructive pulmonary disease (COPD), respiratory symptoms are important determinants of reduced health related quality of life (HRQoL) [12-15]. The prevalence of respiratory symptoms exceeds the combined prevalences of asthma and COPD, and both asthma and COPD are frequently undiagnosed diseases [16-18]. Thus, the high prevalence of respipratory symptoms may mirror undiagnosed and untreated disease.
The common occurrence of respiratory symptoms calls for attention to how these symptoms affect health also in subjects with no diagnosis of obstructive airways disease. Impaired HRQoL in the presence of respiratory symptoms have been found in two population-based studies [6,19], but no study of respiratory sypmtoms and HRQoL have separate analyses for subjects with and without asthma and COPD, and no study provide information about extensive objective measurements of respiratory health.
The ECRHS is a randomly sampled, multi-cultural, population based cohort study. The ECRHS included measurements of atopy, bronchial hyperresponsiveness (BHR), and lung function, and offers a unique opportunity to investigate how respiratory symptoms affect HRQoL among subjects both with and without obstructive lung disease. In the present paper we aimed to: 1) Describe the relationship between respiratory symptoms and HRQoL in an international adult general population and: 2) To assess whether this relationship varied with presence of asthma and/or COPD, or presence of objective functional markers like atopy and BHR.