Epidemiology of Chronic Critical Illness in Japan: A Nationwide Inpatient Database Study

OBJECTIVES: The epidemiology of chronic critical illness is not well known. We aimed to estimate the prevalence, mortality, and costs associated with chronic critical illness in Japan. DESIGN: A nationwide inpatient administrative database study in Japan from April 2011 to March 2018. SETTING: Six hundred seventy-nine acute-care hospitals with ICU beds in Japan. PATIENTS: Adult patients who met our definition for chronic critical illness: one of six eligible clinical conditions (prolonged acute mechanical ventilation, tracheotomy, stroke, traumatic brain injury, sepsis, and severe wound) plus at least 8 consecutive days in an ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among 2,395,016 ICU admissions during the study period, 216,434 (9.0%) met the definition for chronic critical illness. The most common eligible condition was prolonged acute mechanical ventilation (73.9%), followed by sepsis (50.6%), tracheostomy (23.8%), and stroke (22.8%). Overall inhospital mortality was 28.6%. The overall age-specific population prevalence was 42.0 per 100,000. The age-specific population prevalence steadily increased with age, reaching 109.6 per 100,000 in persons aged greater than 85 years. With extrapolation to national estimates in Japan, there were 47,729 chronic critical illness cases in 2011 and the number remained similar at 46,494 cases in 2017. Hospitalization costs increased gradually, rising from U.S.$2.3 billion in 2011 to U.S.$2.7 billion in 2017. Inhospital mortality decreased from 30.6% to 28.2%, whereas the proportion of patients with total/severe dependence increased from 29.6% to 33.2% and the proportion of patients with decreased consciousness at discharge increased from 18.7% to 19.6%. CONCLUSIONS: Using a nationwide inpatient database in Japan, we found substantial clinical and economic burdens of chronic critical illness in Japan. Chronic critical illness was particularly common in elderly people. Although inhospital mortality of chronic critical illness patients continues to decrease, costs and patients with dependence for activities of daily living or decreased consciousness at discharge are increasing.