ORLANDO — Despite a steadily improving mortality picture, patients with childhood-onset type 1 diabetes still faced significantly increased mortality risks in a 40-year prospective follow-up study.
Women were particularly at risk, with a 13-fold greater risk of death than women in the same Pennsylvania community who were free of the disease, Dr. Trevor J. Orchard said.
However, the follow-up study did show improving survival rates. After 30 years, the death rate among those diagnosed in the earliest cohort (1965–1969) was 22%. That dropped to 19% in the 1970–1974 cohort, and to 15% in the 1975–1979 cohort.
“We believe this reflects better care, resulting in fewer deaths early in diagnosis and—more recently—lower rates of diabetes complications,” Dr. Orchard, professor of epidemiology at the University of Pittsburgh, said in an interview.
“A lot of patients and the public feel that individuals with childhood-onset type 1 have lower life expectancy. These data firmly support that this is rapidly changing, and most people with type 1 diabetes can look forward to a normal life span if they keep their blood glucose and other risk factors under control,” he added.
Dr. Orchard presented data collected by his colleague, Aaron Secrest, a PhD candidate at the university. Mr. Secrest based his analysis on the Allegheny County Type 1 Diabetes Registry, one of the largest population-based registries of the disease.
The analysis included 1,075 residents of Allegheny County, Pa., who were diagnosed with childhood-onset type 1 diabetes in 1965–1979. The population was stratified into three time cohorts: those diagnosed in 1965–1969, in 1970–1974, and in 1975–1979, with about one-third of the cohort included in each time period. In all, 48% of the patients were female, and 93% were white; the small percentage of black patients is representative of the county's overall population.
As of January 2008, 19% (202) of registry participants had died—a rate seven times greater than age- and sex-matched people in the general population. Of those 202 participants, 95 were men and 107 were women.
The cumulative survival rates were 98% at 10 years, 93% at 20 years, 81% at 30 years, and 68% at 40 years. “This tells us that about one-third of people with childhood-onset type 1 diabetes diagnosed in the 1960s will die within 40 years of their diagnosis,” Dr. Orchard said.
Although women within the cohort were not significantly more likely to die than men, “striking differences” emerged when the diabetes group was compared to the background population. “Compared to the standardized mortality rate of the county, women [in the cohort] were 13 times more likely to die, and men were 5 times more likely to die,” Dr. Orchard said. The relative mortality differences between cohort and community and the sex differences in relative mortality were highly statistically significant, he said.
Race also factored significantly into the survival curve. “We saw a tremendously high mortality in blacks, such that 30-year survival was down to 57% compared to 83% in whites,” Dr. Orchard said. “However, the standardized mortality ratio for blacks is very much the same [compared to the local county] as it is for whites, illustrating the relatively high mortality rate in the black background community.”
There were 32 deaths among black patients—41% of the black cohort. All of the deaths among blacks were directly related to diabetes.
“As this increase did include both acute and chronic complications of diabetes, it is most likely related to access to care and/or the ability to follow through with that care,” Dr. Orchard said.
Disclosures: The National Institutes of Health funded the study. Neither Dr. Orchard nor Mr. Secrest reported any financial disclosures.
After 30 years, the death rate was 22% in those diagnosed in 1965–1969, and 15% in the 1975–1979 cohort.
Source DR. ORCHARD