Monitoring the occurrence of diabetes mellitus and its major complications: the combined use of different administrative databases

Objective: Diabetes mellitus is a growing public health problem, for which efficient and timely surveillance is a key policy. Administrative databases offer relevant opportunities for this purpose. We aim to monitor the incidence of diabetes and its major complications using administrative data. Study design and methods: We study a population of about 850000 inhabitants in the Veneto Region (Italy) from the end of year 2001 to the end of year 2004. We use four administrative databases with record linkage. Databases of drug prescriptions and of exemptions from medical charge were linked to identify diabetic subjects; hospital discharge records and mortality data were used for the assessment of macrovascular and renal complications and vital status. Results: We identified 30230 and 34620 diabetic subjects at the start and at the end of the study respectively. The row prevalence increased from 38.3/1000 (95% CI 37.2-39.5) to 43.2/1000 (95% CI 42.3-44) for males and from 34.7/1000 (95% CI 33.9-35.5) to 38.1/1000 (95% CI 37.4-39) for females. The mean row incidence is 5.3/1000 (95% CI 5-5.6) person years for males and 4.8/1000 (95% CI 4.4-5.2) person years for females. The rate of hospitalisations for cardiovascular or kidney diseases is greatly increased in diabetic people with respect to non diabetics for both genders. The mortality relative risk is particularly important in younger age classes: diabetic males and females aged 45-64 years present relative risk for death of 1.7 (95% CI 1.58-1.88) and 2.6 (95% CI 2.29-2.97) respectively. Conclusion: This study provides a feasible and efficient method to determine and monitor the incidence and prevalence of diabetes and the occurrence of its complications along with indexes of morbidity and mortality.