Validation of a case definition to define hypertension using administrative data.
We validated the accuracy of case definitions for hypertension derived from administrative data across time periods (year 2001 versus 2004) and geographic regions using physician charts. Physician charts were randomly selected in rural and urban areas from Alberta and British Columbia, Canada, during years 2001 and 2004. Physician charts were linked with administrative data through unique personal health number. We reviewed charts of approximately 50 randomly selected patients >35 years of age from each clinic within 48 urban and 16 rural family physician clinics to identify physician diagnoses of hypertension during the years 2001 and 2004. The validity indices were estimated for diagnosed hypertension using 3 years of administrative data for the 8 case-definition combinations. Of the 3,362 patient charts reviewed, the prevalence of hypertension ranged from 18.8% to 33.3%, depending on the year and region studied. The administrative data hypertension definition of "2 claims within 2 years or 1 hospitalization" had the highest validity relative to the other definitions evaluated (sensitivity 75%, specificity 94%, positive predictive value 81%, negative predictive value 92%, and kappa 0.71). After adjustment for age, sex, and comorbid conditions, the sensitivities between regions, years, and provinces were not significantly different, but the positive predictive value varied slightly across geographic regions. These results provide evidence that administrative data can be used as a relatively valid source of data to define cases of hypertension for surveillance and research purposes.
Department of Community Health Sciences, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta T2N 4N1, Canada. hquan@ucalgary.ca
Hude
H
Quan
Nadia
N
Khan
Brenda R
BR
Hemmelgarn
Karen
K
Tu
Guanmin
G
Chen
Norm
N
Campbell
Michael D
MD
Hill
William A
WA
Ghali
Finlay A
FA
McAlister
D000328:Adult; D000416:Alberta / Q000453:epidemiology; D001955:British Columbia / Q000453:epidemiology; D003625:Data Collection / Q000592:standards*; D003953:Diagnosis-Related Groups; D005260:Female; D006302:Health Services Research; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D015203:Reproducibility of Results; D019035:Rural Health Services / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D019037:Urban Health Services / Q000706:statistics & numerical data