Objective: To determine the occurrence of complications and treatment costs in the first 6 years from diagnosis of Type 2 diabetes in the primary care level.
Design: The German multi-centre, retrospective epidemiological cohort study ROSSO observed patients from diagnosis in 1995-1999 until the end of 2003 or loss to follow-up.
Setting: 192 randomly contacted primary care practices and all patient records of newly diagnosed type 2 diabetes patients.
Participants: All 3,142 patients insured in a public health insurance plan.
Main outcome measures: Diabetes-related complications were documented from patient files. Treatment costs were attributed using the doctor's tariff, hospital DRGs and medication price lists for Germany.
Results: At diagnosis, already 22.4% of patients presented with CHD, 15.4% with CHF, 5.8% with pAOD, 3.1% with stroke and 3.9% with AMI, but less than 0.5% with documented microvascular complications. 7.4% of patients were diagnosed with prior depression and, 5.0% with polyneuropathy. Within a mean of 6.5 years of follow-up 114 patients (3.6%) died. The cumulated occurrence of AMI and stroke rose without a lag phase almost linearly from diagnosis reaching 6.7% for AMI and 7.7% for stroke. The total number of strokes was significantly higher than AMI (181 strokes vs. 109 AMI; p</=0.001). As expected, the rate of microvascular complications was low during this early disease stage but nevertheless reached 2.8 % of patients (amputation, dialysis and blindness combined). Mortality and stroke rates did not differ significantly between sexes but men suffered more frequently from AMI (4.8% men, 2.2% women; p < 0.001). Total costs of diabetes care was 1,288 euro (1,610 $)for the first treatment year with diagnosed diabetes and rose to 3,845 euro (4,806 $) in year seven. Costs for treating complications dominated already in the first year after diagnosis. The mean direct treatment costs amounted to 3,210 euro (4,013 $) per patient and year for the first 6.5 years.
Conclusion: ROSSO is the first epidemiological cohort study examining longitudinal epidemiological data of the same patients over more than five years (up to eight years) for type 2 diabetes mellitus in primary care practices, starting from diagnosis. The rate of complications rose linearly from diagnosis without a lag phase. Stroke occurred more often than myocardial infarction, the latter more often in men. Total treatment costs were dominated by costs of treating complications from early on, suggesting a costs saving potential by early detection of diabetes as well as by secondary prevention and patient empowerment in the period following diagnosis.