Epidemiology and treatment outcome of pneumonia: Analysis based on Japan national database

Pneumonia is the third leading cause of death in Japan. Mortality increases at an accelerating rate in elderly patients aged ≥65 years. Elderly patients tend to have underlying conditions affecting pneumonia treatment. The national database (NDB) associated with medical services under Japanese universal health insurance is available for research purposes. Our NDB randomly sampled 10% of hospitalized patients every October from 2011 to 2014. In this NDB, we analyzed pneumonia epidemiology in patients aged ≥15 years and 30-day mortality in Japanese hospitals. This study also investigated the factors affecting treatment outcome. A total of 9386 patients were entered. The number of patients from age 65 years and older increased greatly, representing 85% of the total. The thirty-day mortality rate among all patients was 11.7%. Mortality rates at age 15-64, 65-74, 75-84, and ≥85 years were 9.5%, 12.0%, 8.3%, and 14.9%, respectively, showing significant differences (P < 0.001). The underlying conditions varied among age groups. Male gender, age, heart failure, chronic kidney disease (CKD), consciousness disorder, shock and respiratory failure are risk factors for 30-day mortality. Pneumonia develops mainly in people aged 65 years and older in Japan, and treatment outcome is generally poor in elderly patients. The underlying conditions were seen to affect the 30-day mortality rate. CURB-65 and ADROP, a modification of CURB-65 in Japan, have already estimated these risk factors, and heart failure and CKD might be additional factors for estimating pneumonia severity.