“Frequent exacerbator” is a phenotype of poor prognosis in Japanese patients with chronic obstructive pulmonary disease

BACKGROUND The prognosis of Japanese patients with COPD who suffer repeated exacerbations is unclear, although Westerners with such episodes have a poor prognosis. MATERIALS AND METHODS We conducted a 1-year prospective observational trial involving 90 Japanese patients with COPD: 58 nonexacerbators, 12 infrequent exacerbators, and 20 frequent exacerbators classified on the basis of exacerbation frequency (zero, one, and two or more exacerbations/year), respectively, during the previous year were observed prospectively for 1 year. The characteristics of frequent exacerbators, the frequency of exacerbation, and the period until the first event were then compared among the groups. RESULTS A total of 78 patients completed the study. Frequent exacerbators had a significantly higher risk of frequent exacerbation in the following year than the case for nonexacerbators (odds ratio [95% confidence interval] 2.94 [1.21-7.17], P=0.0340), but not in comparison with infrequent exacerbators (1.51 [0.49-4.63], P>0.05). The mean annual frequency of exacerbations in the following year was significantly (P=0.0020) higher in the frequent exacerbators (1.4 exacerbations/year) than in the nonexacerbators (0.4), but not in the infrequent exacerbators (0.9, P>0.05). The mean period until the first exacerbation was significantly shorter in the frequent exacerbators than in the infrequent or nonexacerbators (P=0.0012). Independent risk factors for future frequent exacerbation included the presence of gastroesophageal reflux disease, more severe airflow obstruction, and use of inhaled corticosteroids. CONCLUSION Our present results indicate that Japanese COPD patients suffering frequent exacerbation have a poor prognosis. The characteristics of Japanese and Western COPD patients suffering frequent exacerbation are similar.