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Open Access Research article

Osteoporosis-related fracture case definitions for population-based administrative data

Lisa M Lix12*, Mahmoud Azimaee3, Beliz Acan Osman4, Patricia Caetano2, Suzanne Morin5, Colleen Metge2, David Goltzman5, Nancy Kreiger6, Jerilynn Prior7 and William D Leslie2

Author Affiliations

1 School of Public Health, University of Saskatchewan, Saskatoon, Canada

2 University of Manitoba, Winnipeg, Canada

3 Institute for Clinical Evaluative Sciences, Toronto, Canada

4 Health Quality Council, Saskatoon, Canada

5 McGill University, Montreal, Canada

6 University of Toronto, Toronto, Canada

7 University of British Columbia, Vancouver, Canada

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BMC Public Health 2012, 12:301  doi:10.1186/1471-2458-12-301

Published: 26 April 2012

Abstract

Background

Population-based administrative data have been used to study osteoporosis-related fracture risk factors and outcomes, but there has been limited research about the validity of these data for ascertaining fracture cases. The objectives of this study were to: (a) compare fracture incidence estimates from administrative data with estimates from population-based clinically-validated data, and (b) test for differences in incidence estimates from multiple administrative data case definitions.

Methods

Thirty-five case definitions for incident fractures of the hip, wrist, humerus, and clinical vertebrae were constructed using diagnosis codes in hospital data and diagnosis and service codes in physician billing data from Manitoba, Canada. Clinically-validated fractures were identified from the Canadian Multicentre Osteoporosis Study (CaMos). Generalized linear models were used to test for differences in incidence estimates.

Results

For hip fracture, sex-specific differences were observed in the magnitude of under- and over-ascertainment of administrative data case definitions when compared with CaMos data. The length of the fracture-free period to ascertain incident cases had a variable effect on over-ascertainment across fracture sites, as did the use of imaging, fixation, or repair service codes. Case definitions based on hospital data resulted in under-ascertainment of incident clinical vertebral fractures. There were no significant differences in trend estimates for wrist, humerus, and clinical vertebral case definitions.

Conclusions

The validity of administrative data for estimating fracture incidence depends on the site and features of the case definition.