Clinical Research
Validity of Administrative Data for Identifying Patients Who Have Had a Stroke or Transient Ischemic Attack Using EMRALD as a Reference Standard

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Abstract

Background

Surveillance for stroke/transient ischemic attack (TIA) using administrative data has traditionally been limited to reporting patients who had an acute event and were hospitalized. This underestimates the true prevalence because many events do not result in hospitalization. We examined whether the accuracy of administrative data for identifying prevalent stroke/TIA could be improved by using data from both inpatient and outpatient visits.

Methods

An administrative data validation reference standard was developed through chart abstraction of 5000 adult patients randomly sampled from 73,014 patients of 83 family physicians who participate in the Electronic Medical Record Administrative Data Linked Database (EMRALD), in Ontario, Canada.

Results

The prevalence of stroke/TIA in our adult population was 3.0%. An algorithm of 1 hospital record had a sensitivity of 35.3% (27.7%-43.0%) and specificity of 99.8% (99.7%-99.9%), whereas an algorithm of 2 physician billings within 1 year or 1 hospitalization had a sensitivity of 68.0% (95% confidence interval [CI], 60.5%-75.5%) and specificity of 98.9% (95% CI, 98.6%-99.2%) for the identification of patients who had ever had a stroke/TIA. We found that hospitalization data underestimated the prevalence of stroke by > 50% and TIA by > 66% compared with using both hospitalization and physician claims data.

Conclusions

The use of outpatient physician claims data in addition to hospitalization data improves the sensitivity of administrative data for the identification of prevalent stroke/TIA and may be used to estimate the prevalence of cerebrovascular events in large populations and over time.

Résumé

Introduction

La surveillance de l’accident vasculaire cérébral (AVC) et de l'ischémie cérébrale transitoire (ICT) à l’aide des données administratives a traditionnellement été limitée à la déclaration des patients qui étaient hospitalisés à la suite d’un événement aigu. Cela sous-estime la prévalence réelle puisque plusieurs événements n’entraînent pas l’hospitalisation. Nous avons examiné si l’exactitude des données administratives pour déterminer la prévalence de l'AVC et de l'ICT pourrait être améliorée en utilisant les données des hospitalisations et les données des consultations externes.

Méthodes

Un étalon de référence de la validation des données administratives a été développé au moyen des résumés de dossiers de 5000 patients adultes sélectionnés au hasard à partir de 73 014 patients de 83 médecins de famille qui participent à la base de données EMRALD (Electronic Medical Record Administrative Data Linked Database), en Ontario, au Canada.

Résultats

La prévalence de l'AVC et de l'ICT de notre population adulte était de 3,0 %. Un algorithme de 1 dossier d’hôpital avait une sensibilité de 35,3 % (27,7 %-43,0 %) et une spécificité de 99,8 % (99,7 %-99,9 %), tandis qu’un algorithme des honoraires facturés par 2 médecins en 1 an ou de 1 hospitalisation avait une sensibilité de 68,0 % (intervalle de confiance [IC] à 95 %, 60,5 %-75,5 %) et une spécificité de 98,9 % (IC à 95 %, 98,6 %-99,2 %) pour déterminer les patients qui avaient déjà eu un AVC ou un ICT. Nous avons observé que les données d’hospitalisation sous-estimaient la prévalence de l'AVC de > 50 % et l'ICT de > 66 % comparativement à l’utilisation des données des hospitalisations et des données des réclamations des médecins.

Conclusions

L’utilisation des données des déclarations des médecins en consultation externe ainsi que des données des hospitalisations améliore la sensibilité des données administratives pour déterminer la prévalence de l'AVC et de l'ICT et nous pouvons y avoir recours pour estimer la prévalence des événements cérébrovasculaires au sein de vastes populations et au fil du temps.

Section snippets

Methods

The Electronic Medical Record Administrative Data Linked Database (EMRALD) held at the Institute for Clinical Evaluative Sciences was used as the reference standard for the diagnosis of stroke or TIA. EMRALD consists of all clinically relevant information contained in the family physician patient chart of volunteering family physicians in Ontario using Practice Solutions EMR. The data used in this validation study were extracted between June 2011 and November 2011. Patients in this database are

Results

For the 5000 adult patients randomly sampled for chart abstraction, the average age was 51.5 years and 57.5% were women. Among the 83 physicians practicing in 26 geographically distinct clinics, the average years in practice was 18.4 years and the average length of time using EMR was 5.6 years. Overall, the prevalence of stroke in our population was 2.1%, for TIA it was 1.6%, and for stroke and TIA combined it was 3.0%. We found that 61 (59%) of the patients had ischemic strokes, 12 (12%) of

Discussion

We found the ideal algorithm to identify patients who had a stroke or stroke or TIA, or both, was hospitalization or 2 physician billings within a 1-year period. For the identification of patients who had a TIA, the ideal algorithm was 1 hospitalization or emergency department visit or 2 physician billings within 1 year. We found that about 40% of strokes and 20% of TIAs identified using administrative data sources were only identified through physician billing data and were likely milder cases

Acknowledgements

We would like to thank Asako Bienek for her help with the conceptual design and critical review of this manuscript.

This study was supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions, results, and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should

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