Purpose: There are no reports based on long-term observation on mortality caused by Crohn's disease in Japan because of the small number of patients recorded throughout the 1970s. Because Crohn's disease patients in Japan are exempt from medical expenses, Crohn's disease is treated mainly with nutritional therapy and less frequently with corticosteroids. This study sought to estimate mortality and cause of death by Crohn's disease in Japan in the referred population.
Methods: Consecutive patients with Crohn's disease from 1967 to 1997 were identified in the Kyushu and Fukuoka University Study Group's nine affiliated hospitals and were followed up for 8.4 +/- 5.6 years.
Results: Death occurred in 6 of 544 patients. Cumulative survival rates for patients with Crohn's disease were 99.7 percent at 5 years, 99.3 percent at 10 years, and 96.8 percent at 15 years; there was no significant difference between genders or the age-matched expected survival rate of the Japanese population (P = 0.61, 0.84, 0.56). The overall standardized mortality rate was 1.43 (95 percent confidence interval, 0.53-3.12). The standardized mortality rate in newly diagnosed patients who were treated mainly with nutritional therapy was 0.75 (95 percent confidence interval, 0.02-4.18), and 1.69 in referred patients (95 percent confidence interval, 0.55-3.93). The standardized mortality rate by causes of death was high (64.4; 95 percent confidence interval, 7.72-232.5) in rectal cancer. In 150 patients who had been followed up for more than ten years, only 40 percent were administered corticosteroids.
Conclusion: The standardized mortality rate of patients with Crohn's disease in the Kyushu and Fukuoka University Study Group's nine hospitals (the reference unit) was similar to reported rates of cohort studies. The standardized mortality rate of newly diagnosed patients was better than that of referred patients. The better vital prognosis of newly diagnosed patients might be attributable to the influence of frequent nutritional therapy and to lesser steroid use.