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Open Access Research article

Disease identification based on ambulatory drugs dispensation and in-hospital ICD-10 diagnoses: a comparison

Patricia Halfon1*, Yves Eggli2, Anne Decollogny2 and Erol Seker2

Author Affiliations

1 Institute of Social and Preventive Medicine (IUMSP), University Hospital Center and Faculty of Biology and Medicine, Biopole 2, Route de la Corniche 10, 1010, Lausanne, Switzerland

2 Institute of Health Economics and Management, University Hospital Center and University of Lausanne, Route de Chavannes 31, 1015, Lausanne, Switzerland

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BMC Health Services Research 2013, 13:453  doi:10.1186/1472-6963-13-453

Published: 31 October 2013

Abstract

Background

Pharmacy-based case mix measures are an alternative source of information to the relatively scarce outpatient diagnoses data. But most published tools use national drug nomenclatures and offer no head-to-head comparisons between drugs-related and diagnoses-based categories. The objective of the study was to test the accuracy of drugs-based morbidity groups derived from the World Health Organization Anatomical Therapeutic Chemical Classification of drugs by checking them against diagnoses-based groups.

Methods

We compared drugs-based categories with their diagnoses-based analogues using anonymous data on 108,915 individuals insured with one of four companies. They were followed throughout 2005 and 2006 and hospitalized at least once during this period. The agreement between the two approaches was measured by weighted kappa coefficients. The reproducibility of the drugs-based morbidity measure over the 2 years was assessed for all enrollees.

Results

Eighty percent used a drug associated with at least one of the 60 morbidity categories derived from drugs dispensation. After accounting for inpatient under-coding, fifteen conditions agreed sufficiently with their diagnoses-based counterparts to be considered alternative strategies to diagnoses. In addition, they exhibited good reproducibility and allowed prevalence estimates in accordance with national estimates. For 22 conditions, drugs-based information identified accurately a subset of the population defined by diagnoses.

Conclusions

Most categories provide insurers with health status information that could be exploited for healthcare expenditure prediction or ambulatory cost control, especially when ambulatory diagnoses are not available. However, due to insufficient concordance with their diagnoses-based analogues, their use for morbidity indicators is limited.

Keywords:
Case mix; Pharmacy data; Ambulatory care; Drug utilization; Kappa coefficients