Validation of a Case Definition to Define Hypertension Using Administrative Data

Abstract

Abstract-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 Ϸ50 randomly selected patients Ͼ35 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 3362 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 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.

Association between First Nations ethnicity and progression to kidney failure by presence and severity of albuminuria

“…Diabetes and hypertension were identified from hospital discharge records and physicians' billing claims using validated algorithms. 17,18 Comorbid conditions were defined from physician claims and hospital admissions data using validated coding algorithms and the clinical modification of the International Classification of Diseases, 9th revision, and the International Classification of Diseases, 10th revision. 19 Health services data were captured for all residents of Alberta during the study period, regardless of movement within the province.…”

The safety of combining angiotensin-converting-enzyme inhibitors with angiotensin-receptor blockers in elderly patients: a population-based longitudinal analysis

“…12, 15 We defined baseline use of medications as use of drugs prescribed concomitant with, or in the 120 days before, the index prescription of an ACE inhibitor or an angiotensin-receptor blocker.…”

Estimating the Burden of Osteoarthritis to Plan for the Future

“…Although individuals responsible for ICD coding in the DAD receive standardized training in Canada (33), there may still be coding variations across provinces that could limit the generalizability of these findings. Previous studies have compared the validity of case identification using administrative data against chart review in the areas of hypertension and diabetes mellitus, and found that the sensitivity results (diabetes mellitus range 90.2-92.1%, hypertension range 74.0-76.0%) are not significantly different between 2 provinces (Alberta and British Columbia) (21,24).…”

“…The sensitivity and specificity of OA case definition are not high; however, these are the standard algorithms accepted for administrative database OA research. Further, previous research in other chronic disease areas have determined the case definition with the highest validity to be 2 physician claims within 2 years, or 1 hospitalization, with a minimum of 3 or more years of data (21)(22)(23)(24). Our estimates include only individuals who have accessed health care services paid for by the provincial health care insurance plan.…”

“…Further, research in diabetes mellitus, hypertension, and other chronic diseases have determined the case definition with the highest validity to be 2 physician claims within 2 years, or 1 hospitalization, with a minimum of 3 or more years of data (21)(22)(23)(24).…”