Mortality trends in type 1 diabetes - The Allegheny County (Pennsylvania) Registry 1965-1999

OBJECTIVES - To investigate long-term mortality and its temporal trends as of 1 January 1999 among the 1,075 patients with type 1 diabetes (onset age <18 years, diagnosed between 1965 and 1979) who comprise the Allegheny Coun ty population-based registry. RESEARCH DESIGN AND METHODS- Overall, sex- and race-specific mortality rate s per person-year of follow-up were determined Standardized mortality ratio s were also calculated. Survival analyses and Cox proportional hazard model were also used. Temporal trends were examined by dividing the cohort into three groups by year of diagnosis (1965-1969, 1970-1974. and 1975-1979). RESULTS - Living status of 972 cases was ascertained as of January 1, 1999 (ascertainment rate 90.4%). The mean duration of diabetes was 25.2 +/- 5.8 (SD) years. Overall, 170 deaths were observed. The crude mortality rate was 627 per 100,000 person-years (95% CI 532-728) and standardized mortality r atio was 519 (440-602). Life-table analyses by the Kaplan-Meier method indi cated cumulative survival rates of 98.0% at 10 years, 92.1% at 20 years, an d 79.6% at 30 years duration of diabetes. There was a significant improveme nt in the survival rate between the cohort diagnosed during 1965-1969 and t hat diagnosed during 1975-1979 by the log-rank test (P = 0.03). Mortality w as higher in African-Americans than in Caucasians, but there were no differ ences seen by sex. The improvement in recent years was seen in both ethnic groups and sexes. CONCLUSIONS - An improvement in long-term survival was observed in the more recently diagnosed cohort. This improvement is consistent with the introdu ction of HbA(1) testing, home blood glucose monitoring, and improved blood pressure therapy in the 1980s.