Estimated numbers of patients with intractable respiratory diseases

To estimate the number of patients with intractable respiratory diseases, we conducted a two-stage nationwide epidemiological survey in 1997. The first survey was performed at randomly sampled hospitals to identify the number of patients treated. The second survey sought detailed clinico-epidemiological data on the patients reported in the first survey. The response rates were 54% for the first survey and 62% for the second. Based on the survey findings, we derived the following nationwide estimates: 450 patients (95% confidence interval: 360-530) with chronic thromboembolic pulmonary hypertension; 230 (200-260) with primary pulmonary hypertension; 180 (150-210) with obesity-associated hypoventilation syndrome; 40 (30-50) with primary alveolar hypoventilation syndrome; 160 (140-180) with histiocytosis X; and 190 (150-230) with juvenile pulmonary emphysema.