Osteoporosis International

, Volume 24, Issue 3, pp 801–810

Magnitude and consequences of misclassification of incident hip fractures in large cohort studies: the Study of Osteoporotic Fractures and Medicare claims data

  • J. T. Schousboe
  • M. L. Paudel
  • B. C. Taylor
  • B. A. Virnig
  • J. A. Cauley
  • J. R. Curtis
  • K. E. Ensrud
Original Article

DOI: 10.1007/s00198-012-2210-8

Cite this article as:
Schousboe, J.T., Paudel, M.L., Taylor, B.C. et al. Osteoporos Int (2013) 24: 801. doi:10.1007/s00198-012-2210-8

Abstract

Summary

In the Study of Osteoporotic Fractures (SOF), 18.5 % of incident hip fractures identified in Medicare Fee-for-Service claims data were not reported to or confirmed by the cohort. Cognitive impairment was a modest risk factor for false-negative hip fracture ascertainment via self-report.

Introduction

Prospective cohort studies of fractures that rely on participant self-report to be the initial signal of an incident fracture could be prone to bias if a significant proportion of fractures are not self-reported.

Methods

We used data from the SOF merged with Medicare Fee-for-Service claims data to estimate the proportion of participants who had an incident hip fracture identified in Medicare claims that was either not self-reported or confirmed (by review of radiographic reports) in SOF.

Results

Between 1/1/1991 and 12/31/2007, 647 SOF participants had a hip fracture identified in Medicare claims, but 120 (18.5 %) were either not reported to or confirmed by the cohort. False-negative hip fracture ascertainment was associated with a reduced modified Mini-Mental State Exam (MMSE) score (odds ratio 1.31 per SD decrease, 95 % C.I. 1.06–1.63). Point estimates of associations of predictors of incident hip fracture were changed minimally when the misclassification of incident hip fracture status was corrected with use of claims data.

Conclusions

A substantial minority of incident hip fractures were not reported to or confirmed in the SOF. Cognitive impairment was modestly associated with false-negative hip fracture ascertainment. While there was no evidence to suggest that misclassification of incident hip fracture status resulted in biased associations of potential predictors with hip fracture in this study, false-negative incident fracture ascertainment in smaller cohort studies with limited power may increase the risk of type 2 error (not finding significant associations of predictors with incident fractures).

Keywords

Cohort studies False-negative ascertainment of fractures Hip fracture Medicare claims data Misclassification of fractures 

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2012

Authors and Affiliations

  • J. T. Schousboe
    • 1
    • 2
  • M. L. Paudel
    • 3
  • B. C. Taylor
    • 3
    • 4
    • 5
  • B. A. Virnig
    • 2
  • J. A. Cauley
    • 6
  • J. R. Curtis
    • 7
  • K. E. Ensrud
    • 3
    • 4
    • 5
  1. 1.Park Nicollet InstituteMinneapolisUSA
  2. 2.Division of Health Policy and ManagementUniversity of MinnesotaMinneapolisUSA
  3. 3.Division of EpidemiologyUniversity of MinnesotaMinneapolisUSA
  4. 4.Center for Chronic Diseases Outcomes Research, Department of Veterans Affairs Health Care SystemMinneapolisUSA
  5. 5.Department of MedicineUniversity of MinnesotaMinneapolisUSA
  6. 6.Department of EpidemiologyUniversity of PittsburghPittsburghUSA
  7. 7.Division of Clinical Immunology and RheumatologyUniversity of Alabama at BirminghamBirminghamUSA