THE DIABETES AUDIT AND RESEARCH IN TAYSIDE SCOTLAND (DARTS) STUDY - ELECTRONIC RECORD LINKAGE TO CREATE A DIABETES REGISTER

Objectives: To identify all patients with diabetes in a community usin g electronic record linkage of multiple data sources and to compare th is method of case ascertainment with registers of diabetic patients de rived from primary care.Design: Electronic capture-recapture linkage o f records included data on all patients attending hospital diabetes cl inics, all encashed prescriptions for diabetes related drugs and monit oring equipment, all patients discharged from hospital, patients atten ding a mobile unit for eye screening, and results for glycated haemogl obin and plasma glucose concentrations from the regional biochemistry database, Diabetes registers from primary care were from a random samp le of eight Tayside general practices. A detailed manual study of rele vant records for the 35 144 patients registered with these eight gener al practices allowed for validation of the case ascertainment. Setting : Tayside region of Scotland, population 391 274 on 1 January 1996. Ma in outcome measures: Prevalence of diabetes; population of patients id entified by different data sources; sensitivity and positive predictiv e value of ascertainment methods. Results: Electronic record linkage i dentified 7596 diabetic patients, giving a prevalence of known diabete s of 1.94% (0.21% insulin dependent diabetes, 1.73% non-insulin depend ent): 63% of patients had attended hospital diabetes clinics, 68% had encashed diabetes related prescriptions, 72% had attended the mobile e ye screening unit, and 48% had biochemical results diagnostic of diabe tes. A further 701 patients had isolated hyperglycaemia (plasma glucos e > 11.1 mmol/l) but were not considered diabetic by general practitio ners. Validation against the eight general practices (636 diabetic pat ients) showed electronic linkage to have a sensitivity of 0.96 and a p ositive predictive value of 0.95 for ascertainment of known diabetes. General practice lists had a sensitivity of 0.91 and a positive predic tive value of 0.98. Conclusions: Electronic record linkage was more se nsitive than general practice registers in identifying diabetic subjec ts and identified an additional 0.18% of the population with a history of hyperglycaemia who might warrant screening for undiagnosed diabete s.