Background: For a number of chronic diseases, health-related quality of life (HRQoL) has become an important outcome measure. Little data are available on how incidence, remission, or persistence of respiratory symptoms affect HRQoL.
Methods: The Hordaland County Cohort Study was conducted between 1985 and 1997, and comprised 3,786 subjects, randomly selected, and aged 15 to 70 years in 1985. Respiratory symptoms were assessed both in 1985 and 1996/1997, and HRQoL was measured by the Short-Form 12 questionnaire in 1996/1997. Robust linear regression analysis was used to examine the relationship between changes in six respiratory symptoms and the physical component score (PCS) and mental component score (MCS).
Results: Among subjects with incidence or persistence of any of the six examined respiratory symptoms, PCS and MCS were significantly lower than among subjects without symptoms. The PCS was more reduced than the MCS in symptomatic subjects; however, this trend was reduced after adjustment for the confounder's gender, age, educational level, body mass index, and smoking status. Dyspnea attacks and dyspnea grade 2 had the largest negative impact on both PCS and MCS.
Conclusions: This is the first longitudinal population study to show the negative impact of incidence and persistence of respiratory symptoms on HRQoL.