Mortality Trends in Patients With and Without Diabetes in Ontario, Canada and the UK From 1996 to 2009: A Population-Based Study

Study Questions:

Have mortality rates changed over time among adults with and without diabetes?

Methods:

Population-based health care databases from the province of Ontario, Canada, and The Health Improvement Network (THIN) database from the United Kingdom (UK) were used to identify patients with and without diabetes. For the Canadian data, persons were defined as having diabetes in a given year and being ages at least 20 years if they had one hospitalization or two physician claims bearing a diagnosis of diabetes within a 2-year period. UK data were obtained from the THIN database, a computerized medical research database that contains systematically recorded data on more than 3 million patients seen at primary care practices in the UK; a representative of this population with respect to age, sex, and geographical distribution. All individuals with a diagnosis of diabetes mellitus recorded by the primary care practitioner were identified with an automatic search. Annual age- and sex-adjusted mortality rates were compared for adults (>20 years old) with and without diabetes from January 1996 to December 2009.

Results:

In Ontario, the prevalence of diabetes increased consistently with time, from 5.4% in 1996 to 11.4% in 2009. In the UK data, the prevalence of diabetes increased from 3.2% to 5.9% from 1996 to 2009. The excess risk of mortality for individuals with diabetes in both cohorts was significantly lower during later versus earlier years of the follow-up period (1996-2009). In Ontario, the diabetes mortality rate ratio decreased from 1.90 (95% confidence interval [CI], 1.86-1.94) in 1996 to 1.51 (1.48-1.54) in 2009, and in THIN from 2.14 (1.97-2.32) to 1.65 (1.57-1.72), respectively. In Ontario and THIN, the mortality rate ratios among individuals with diabetes in 2009 were 1.16 (1.13-1.19) and 1.24 (1.17-1.30) for those ages 65-74 years, and 1.23 (1.20-1.26) and 1.25 (1.18-1.31) for those ages over 74 years, respectively. Corresponding rate ratios in Ontario and THIN were 1.94 (1.84-2.04) and 2.23 (1.98-2.50) for individuals ages 45-64 years, and 1.70 (1.63-1.78) and 1.79 (1.63-1.95) for those ages 20-44 years.

Conclusions:

The investigators concluded that the excess risk of mortality in individuals with versus without diabetes has decreased over time in both Canada and the UK. This may be in part due to earlier detection and higher prevalence of early diabetes, as well as to improvements in diabetes care.

Perspective:

These data suggest that although the prevalence of diabetes has increased, the mortality rate for those with versus without diabetes has not. However, adults with diabetes are likely to have increased comorbidities, which likely translate into higher rates of disability and lower overall quality of life. Further research on the overall costs related to this chronic condition is warranted.

Keywords: Risk, Great Britain, Disabled Persons, Follow-Up Studies, Early Diagnosis, Canada, Cardiovascular Diseases, Transcription Factors, Ontario, Databases, Factual, Primary Health Care, Diabetes Mellitus


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