Long-Term Mortality in Nationwide Cohorts of Childhood-Onset Type 1 Diabetes in Japan and Finland
- Keiko Asao, MD, MPH12,
- Cinzia Sarti, MD, PHD3,
- Tom Forsen, MD34,
- Valma Hyttinen, MSC3,
- Rimei Nishimura, MD, MPH1,
- Masato Matsushima, MD, MPH5,
- Antti Reunanen, MD, PHD6,
- Jaakko Tuomilehto, MD, MPOLSC, PHD34,
- Naoko Tajima, MD1 and
- for the Diabetes Epidemiology Research International (DERI) Mortality Study Group
- 1Division of Diabetes and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
- 2Department of Public Health and Environmental Medicine, Jikei University School of Medicine, Tokyo, Japan
- 3Diabetes and Genetic Epidemiology Unit, Department of Epidemiology and Health Promotion, National Public Health Institute, Helsinki, Finland
- 4Department of Public Health, University of Helsinki, Helsinki, Finland
- 5Department of General Medicine, Jikei University School of Medicine, Tokyo, Japan
- 6Department of Health and Functional Capacity, National Public Health Institute, Helsinki, Finland
- Address correspondence and reprint requests to Naoko Tajima, MD, Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishishimbashi, Minato-ku, Tokyo 105-8461, Japan. E-mail: ntajima{at}jikei.ac.jp.
Abstract
OBJECTIVE—This study compares mortality from type 1 diabetes in Japan and Finland and examines the effects of sex, age at diagnosis, and calendar time period of diagnosis on mortality.
RESEARCH DESIGN AND METHODS—Patients with type 1 diabetes from Japan (n = 1,408) and Finland (n = 5,126), diagnosed from 1965 through 1979, at age <18 years, were followed until 1994. Mortality was estimated with and without adjustment for that of the general population to assess absolute and relative mortality using Cox proportional hazard models.
RESULTS—Overall mortality rates in Japan and Finland were 607 (95% CI 510–718) and 352 (315–393), respectively, per 100,000 person-years; standardized mortality ratios were 12.9 (10.8–15.3) and 3.7 (3.3–4.1), respectively. Absolute mortality was higher for men than for women in Finland, but relative mortality was higher for women than for men in both cohorts. Absolute mortality was higher in both cohorts among those whose diabetes was diagnosed during puberty, but relative mortality did not show any significant difference by age at diagnosis in either cohort. In Japan, both absolute and relative mortality were higher among those whose diagnosis was in the 1960s rather than the 1970s.
CONCLUSIONS—Mortality from type 1 diabetes was higher in Japan compared with Finland. The increased risk of death from type 1 diabetes seems to vary by sex, age at diagnosis, and calendar time period of diagnosis. Further investigation, especially on cause-specific mortality, is warranted in the two countries.
Footnotes
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A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
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- Accepted April 6, 2003.
- Received October 17, 2002.
- DIABETES CARE
