Do frequent moderate exacerbations contribute to progression of chronic obstructive pulmonary disease in patients who are ex-smokers?
BACKGROUND
In addition to smoking, acute exacerbations are considered to be a contributing factor to progression of chronic obstructive pulmonary disease (COPD). However, these findings come from studies including active smokers, while results in ex-smokers are scarce and contradictory. The purpose of this study was to evaluate if frequent acute moderate exacerbations are associated with an accelerated decline in forced expiratory volume in one second (FEV1) and impairment of functional and clinical outcomes in ex-smoking COPD patients.


METHODS
A cohort of 100 ex-smoking patients recruited for a 2-year follow-up study was evaluated at inclusion and at 6-monthly scheduled visits while in a stable condition. Evaluation included anthropometry, spirometry, inspiratory capacity, peripheral capillary oxygen saturation, severity of dyspnea, a 6-minute walking test, BODE (Body mass index, airflow Obstruction, Dyspnea, Exercise performance) index, and quality of life (St George's Respiratory Questionnaire and Chronic Respiratory Disease Questionnaire). Severity of exacerbation was graded as moderate or severe according to health care utilization. Patients were classified as infrequent exacerbators if they had no or one acute exacerbation/year and frequent exacerbators if they had two or more acute exacerbations/year. Random effects modeling, within hierarchical linear modeling, was used for analysis.


RESULTS
During follow-up, 419 (96% moderate) acute exacerbations were registered. At baseline, frequent exacerbators had more severe disease than infrequent exacerbators according to their FEV1 and BODE index, and also showed greater impairment in inspiratory capacity, forced vital capacity, peripheral capillary oxygen saturation, 6-minute walking test, and quality of life. However, no significant difference in FEV1 decline over time was found between the two groups (54.7±13 mL/year versus 85.4±15.9 mL/year in frequent exacerbators and infrequent exacerbators, respectively). This was also the case for all other measurements.


CONCLUSION
Our results suggest that frequent moderate exacerbations do not contribute to accelerated clinical and functional decline in COPD patients who are ex-smokers.