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The diabetes audit and research in Tayside Scotland (darts) study: electronic record linkage to create a diabetes register

BMJ 1997; 315 doi: https://doi.org/10.1136/bmj.315.7107.524 (Published 30 August 1997) Cite this as: BMJ 1997;315:524
  1. Andrew D Morris, senior lecturera,
  2. Douglas IR Boyle, computer programmerb,
  3. Ritchie MacAlpine, research nurseb,
  4. Alistair Emslie-Smith, general practitionerc,
  5. Roland T Jung, consultant physiciand,
  6. Ray W Newton, consultant physiciand,
  7. Thomas M MacDonald, clinical reader

    for the DARTS/MEMO Collaboration

    b
  1. a University Department of Medicine, Ninewells Hospital and Medical School, Dundee DD1 9SY
  2. b Medicines Monitoring Unit, Ninewells Hospital and Medical School, Dundee
  3. c Wallacetown Health Centre, Dundee DD4 6RD
  4. d Diabetes Centre, Ninewells Hospital and Medical School, Dundee
  1. Correspondence to: Andrew D Morris
  • Accepted 19 June 1997

Abstract

Objectives: To identify all patients with diabetes in a community using electronic record linkage of multiple data sources and to compare this method of case ascertainment with registers of diabetic patients derived from primary care.

Design: Electronic capture-recapture linkage of records included data on all patients attending hospital diabetes clinics, all encashed prescriptions for diabetes related drugs and monitoring equipment, all patients discharged from hospital, patients attending a mobile unit for eye screening, and results for glycated haemoglobin and plasma glucose concentrations from the regional biochemistry database. Diabetes registers from primary care were from a random sample of eight Tayside general practices. A detailed manual study of relevant records for the 35 144 patients registered with these eight general practices allowed for validation of the case ascertainment.

Setting: Tayside region of Scotland, population 391 274 on 1 January 1996.

Main outcome measures: Prevalence of diabetes; population of patients identified by different data sources; sensitivity and positive predictive value of ascertainment methods.

Results: Electronic record linkage identified 7596 diabetic patients, giving a prevalence of known diabetes of 1.94% (0.21% insulin dependent diabetes, 1.73% non-insulin dependent): 63% of patients had attended hospital diabetes clinics, 68% had encashed diabetes related prescriptions, 72% had attended the mobile eye screening unit, and 48% had biochemical results diagnostic of diabetes. A further 701 patients had isolated hyperglycaemia (plasma glucose >11.1 mmol/l) but were not considered diabetic by general practitioners. Validation against the eight general practices (636 diabetic patients) showed electronic linkage to have a sensitivity of 0.96 and a positive predictive value of 0.95 for ascertainment of known diabetes. General practice lists had a sensitivity of 0.91 and a positive predictive value of 0.98.

Conclusions: Electronic record linkage was more sensitive than general practice registers in identifying diabetic subjects and identified an additional 0.18% of the population with a history of hyperglycaemia who might warrant screening for undiagnosed diabetes.

Key messages

  • It has been recommended that regional registers of patients with diabetes are established in order to facilitate effective monitoring and treatment of diabetes

  • In Tayside we created a diabetes register by record linkage of multiple data sources: all patients attending hospital diabetes clinics, all encashed prescriptions for diabetes related drugs and monitoring equipment, all patients discharged from hospital, patients attending a mobile unit for eye screening, and results for glycated haemoglobin and plasma glucose concentrations from the regional biochemistry database

  • This register identified 7596 patients with diabetes in Tayside, giving a prevalence of diabetes of 1.94%

  • Record linkage was more sensitive than general practice registers in ascertaining cases of known diabetes

  • A unique patient identifier, the community health number, was fundamental for successful record linkage

Footnotes

    • Accepted 19 June 1997
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