Mortality in GOLD stages of COPD and its dependence on symptoms of chronic bronchitis
Research output: Contribution to journal › Article
Background: The GOLD classification of COPD severity introduces a stage 0 ( at risk) comprising individuals with productive cough and normal lung function. The aims of this study were to investigate total mortality risks in GOLD stages 0 - 4 with special focus on stage 0, and furthermore to assess the influence of symptoms of chronic bronchitis on mortality risks in GOLD stages 1 - 4. Method: Between 1974 and 1992, a total of 22 044 middle-aged individuals participated in a health screening, which included a spirometry as well as recording of respiratory symptoms and smoking habits. Individuals with comorbidity at baseline ( diabetes, stroke, cancer, angina pectoris, or heart infarction) were excluded from the analyses. Hazard ratios (HR 95% CI) of total mortality were analyzed in GOLD stages 0 - 4 with individuals with normal lung function and without symptoms of chronic bronchitis as a reference group. HR: s in smoking individuals with symptoms of chronic bronchitis within the stages 1 - 4 were calculated with individuals with the same GOLD stage but without symptoms of chronic bronchitis as reference. Results: The number of deaths was 3674 for men and 832 for women based on 352 324 and 150 050 person-years respectively. The proportion of smokers among men was 50% and among women 40%. Self reported comorbidity was present in 4.6% of the men and 6.6% of the women. Among smoking men, Stage 0 was associated with an increased mortality risk, HR; 1.65 ( 1.32 - 2.08), of similar magnitude as in stage 2, HR; 1.41 ( 1.31 - 1.70). The hazard ratio in stage 0 was significantly higher than in stage 1 HR; 1.13 ( 0.98 - 1.29). Among male smokers with stage 1; HR: 2.04 ( 1.34 - 3.11), and among female smokers with stage 2 disease; HR: 3.16 ( 1.38 - 7.23), increased HR: s were found in individuals with symptoms of chronic bronchitis as compared to those without symptoms of chronic bronchitis. Conclusion: Symptoms fulfilling the definition of chronic bronchitis were associated with an increased mortality risk among male smokers with normal pulmonary function ( stage 0) and also with an increased risk of death among smoking individuals with mild to moderate COPD ( stage 1 and 2).
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Publication status||Published - 2005|