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Validation of a case definition to define hypertension using administrative data
Hude Quan1, Nadia Khan, Brenda R Hemmelgarn
1Department of Community Health Sciences, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta T2N 4N1, Canada. hquan@ucalgary.ca
Hypertension (Dallas, Tex. : 1979)
|October 28, 2009
Summary
Administrative data accurately identifies hypertension cases using a definition of "2 claims within 2 years or 1 hospitalization." This method is reliable for public health surveillance and research, showing high validity across different regions and time periods.
Area of Science:
- Health Informatics
- Epidemiology
- Public Health Surveillance
Background:
- Accurate case definitions are crucial for hypertension surveillance and research.
- Administrative data offers a potentially vast and cost-effective data source.
- Validation of administrative data definitions against physician charts is necessary.
Purpose of the Study:
- To validate the accuracy of hypertension case definitions derived from administrative data.
- To compare the validity of different case definitions across time and geographic regions.
- To assess the utility of administrative data for hypertension case identification.
Main Methods:
- Physician charts were randomly selected from urban and rural family physician clinics in Alberta and British Columbia, Canada (2001-2004).
- Charts were linked to administrative data using unique personal health numbers.
- Validity indices (sensitivity, specificity, PPV, NPV, kappa) were calculated for 8 case definitions using physician diagnoses as the gold standard.
Main Results:
- The prevalence of hypertension ranged from 18.8% to 33.3% based on the year and region.
- The definition '2 claims within 2 years or 1 hospitalization' demonstrated the highest validity (sensitivity 75%, specificity 94%, PPV 81%, NPV 92%, kappa 0.71).
- Sensitivities were consistent across regions, years, and provinces after adjustments, though positive predictive value showed slight regional variation.
Conclusions:
- Administrative data, particularly the '2 claims within 2 years or 1 hospitalization' definition, is a relatively valid source for identifying hypertension cases.
- This validated definition supports the use of administrative data for large-scale hypertension surveillance and research.
- Findings suggest administrative data can reliably define hypertension cases for public health initiatives.
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