Malnutrition, Airflow Limitation and Severe Emphysema are Risks for Exacerbation of Chronic Obstructive Pulmonary Disease in Japanese Subjects: A Retrospective Single-Center Study

Background: Different characteristics of patients with chronic obstructive pulmonary disease (COPD) between Western and Japanese populations have been reported. Risk factors for COPD exacerbation have been reported in Western countries but have not been studied in Japan.

Patients and methods: We retrospectively examined risk factors for COPD exacerbation. A total of 156 Japanese patients were enrolled, and the records of 136 patients were analyzed.

Results: In the exacerbation group (n=60), body mass index, forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), the FEV₁/FVC ratio (FEV₁/FVC), the percent predicted values of FEV₁ (%FEV₁), and serum total protein (TP) and albumin concentrations were lower, and age, mortality rate, frequency of common cold and pneumonia, COPD severity rankings, modified Medical Research Council (mMRC) dyspnea score, and proportions of patients with severe emphysema (>50% of low attenuation area) and receiving long-term oxygen therapy were higher than those in the nonexacerbation group (n=76). However, the proportion of patients with a greater number of eosinophils (≥200/μL and/or ≥2%) and the exhaled nitric oxide concentration did not differ between the two groups. In the univariate analysis, the risk factors for exacerbation were age; long-term oxygen therapy; low FVC, FEV₁, FEV₁/FVC and %FEV₁; high COPD severity ranking and mMRC score; severe emphysema; hypoproteinemia (<6.5 g/dL); hypoalbuminemia (<3.5 g/dL); leukocytosis; lymphocytopenia; and anemia. In the multivariate analysis, the risk factors were hypoalbuminemia, hypoproteinemia and low FEV₁. Additionally, in patients in the exacerbation-induced mortality subgroup, age, exacerbation frequency, mMRC score and the proportion of patients with lymphocytopenia were higher, and FVC, %FVC, FEV₁, serum TP concentration and the lymphocyte number were lower than those in the exacerbation survival subgroup.

Conclusion: Malnutrition, airflow limitation and severe emphysema were risks for exacerbation and mortality associated with infection in Japanese patients with COPD.