Unique Mortality Profile in Japanese Patients with COPD: An Analysis from the Hokkaido COPD Cohort Study

Causes of death may be unique and different in Japanese patients with COPD because they are generally older, thinner, experience fewer exacerbations, and live longer than those in other countries. We investigated the detailed mortality profile in the Hokkaido COPD cohort study, which completed a 10-year follow-up with a very low dropout rate.

We prospectively examined the 10-year natural history in 279 Japanese patients with COPD (GOLD 1, 26%; GOLD 2, 45%; GOLD 3, 24%; and GOLD 4, 5%). The majority of patients were male, and the average age at baseline was 69 years old. About 95% of all patients had accurate mortality data. The risk factors for mortality were also analyzed.

During the 10 years, 112 patients (40%) died. Their median survival time was 6.1 years (interquartile range: 4.7-7.9 years), and age at death was 79 ± 6 years old (mean ± SD). Respiratory diseases, including pneumonia, were the leading causes of death in 45 (40%), followed by lung cancer in 24 (21%), other cancers in 18 (16%), and cardiovascular diseases in 12 (11%). In particular, lung cancer-related death was equally distributed across all COPD stages, with a higher proportion of lung cancer in the relatively younger generation (<64 years old). Older age at baseline, lower BMI, and severer emphysema were significant risk factors for all-cause mortality.

The unique mortality profile observed in this study should be considered when designing strategies for the management of patients with COPD in any geographic region.