Identifying Ontarians with Type 2 Diabetes Mellitus in Administrative Data: A Comparison of Two Case Definitions

IntroductionThis study compared two previously validated sensitive and specific diabetes case definitions to explore the impact of different classification methods in Ontario ICES administrative data.MethodsThis study included patients captured by the Ontario Diabetes Database with type 2 diabetes using either the sensitive cohort definition (≥ 2 physician visits for diabetes within 1 year or ≥ 1 drug claim for diabetes or ≥ 1 hospitalization with diabetes), or the specific cohort definition (≥ 3 physician visits for diabetes within 1 year), between October 1, 2013 to September 30, 2015. Each cohort's demographic and clinical features were described using descriptive analysis.ResultsUsing sensitive and specific definitions, 1,093,812 and 783,228 patients with type 2 diabetes were identified, respectively. Overall, the demographic and clinical characteristics were similar between cohorts. Patients in the sensitive cohort had mean age of 64.1 years and were 52.4% male, compared to 64.8 years and 53.6% male in the specific cohort. In the sensitive and specific cohorts respectively, 64.4% and 55.7% of patients reported one-year mean HbA1c of < 7% (53 mmol/mol) and 25.3% and 31.5% reported levels between 7.0–8.5% (53–69 mmol/mol).ConclusionsAlthough sample sizes were different between sensitive and specific cohorts, demographic and clinical characteristics were similar.