title: Can the prevalence of diagnosed diabetes be estimated from linked national health records? The validity of a method applied in New Zealand.
abstract: BACKGROUND
  With projected global increases in the prevalence of Type 2 diabetes, the health sector requires timely assessments of the prevalence of this disease to monitor trends, plan services, and measure the efficacy of prevention programmes.
  
  
  OBJECTIVE
  To assess the validity of a method to estimate the prevalence of diagnosed diabetes from linked national health records.
  
  
  METHODS
  We measured the agreement between a diabetes diagnosis (using combined national lists of drug dispensing, outpatient attendance, laboratory tests (HbA1c) and hospital diagnoses) and a primary care diabetes diagnosis in a (PREDICT™) cohort of 53,911 adult New Zealanders. The completeness of the diagnosis of diabetes in the cohort was estimated using capture-recapture methods.
  
  
  RESULTS
  The primary care cohort had a high prevalence of recorded diabetes (20.9%, 11,266/53,911), similar to our derived prevalence of 20.1%. Of the participants with a diagnosis of diabetes, 89% (10,182/11,266) had a similar derived diagnosis, indicating that only about one in 10 people with a primary care diagnosis had not been either admitted to hospital, seen at outpatient clinics, prescribed diabetes drugs or undertaken regular HbA1c tests. The capture-recapture prevalence of diagnosed diabetes in this cohort was 23.7% indicating that primary care diagnoses in the cohort were about 90% complete.
  
  
  CONCLUSIONS
  A method for estimating the prevalence of diagnosed diabetes from national health data shows high-level agreement with primary care records. Linked health data can provide an efficient method for estimating the prevalence of diagnosed diabetes in regions where such records are individually linked.
authors: Department of Epidemiology and Biostatistics, School of Population Health, The University of Auckland, Auckland, New Zealand. sithor@woosh.co.nz
authors: Simon
authors: S
authors: Thornley
authors: Craig
authors: C
authors: Wright
authors: Roger
authors: R
authors: Marshall
authors: Gary
authors: G
authors: Jackson
authors: Paul L
authors: PL
authors: Drury
authors: Susan
authors: S
authors: Wells
authors: James
authors: J
authors: Smith
authors: Wing Cheuk
authors: WC
authors: Chan
authors: Romana
authors: R
authors: Pylypchuk
authors: Rod
authors: R
authors: Jackson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence; D011320:Primary Health Care / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D055815:Young Adult