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Cardiovascular outcome ascertainment was similar using blinded and unblinded adjudicators in a national prospective

Gaurav Parmar1, Pallavi Ghuge, Jewell H Halanych

  • 1Division of Preventive Medicine, Department of Medicine, University of Alabama at Birmingham, AL, USA. gparmar@dopm.uab.edu

Journal of Clinical Epidemiology
|May 1, 2010
PubMed

Insights

Blinding medical records to race and geography in observational studies is costly and may not improve outcome accuracy. Unblinded reviews showed good to excellent agreement for cardiovascular events, suggesting blinding may be an unnecessary expense.

Area of Science:

  • Epidemiology
  • Clinical Research Methodology

Background:

  • Blinding medical records in observational studies can prevent bias but incurs significant costs.
  • Assessing the necessity of blinding for specific patient characteristics like race and geography is crucial for cost-effectiveness.

Purpose of the Study:

  • To evaluate the impact of blinding patient race and geographic location on the accuracy of outcome ascertainment in observational studies.
  • To determine if the cost of blinding is justified by improvements in outcome adjudication.

Main Methods:

  • The study analyzed data from the Reasons for Geographic and Racial Differences in Stroke - Myocardial Infarction (REGARDS-MI) Study, a subset of the REGARDS national prospective cohort.
  • 116 suspected cardiovascular events were initially adjudicated with blinding for race and geography, then re-adjudicated without blinding.
  • Differences in outcome ascertainment were assessed using Cohen's kappa statistic and agreement rates (ARs).

Main Results:

  • Agreement between blinded and unblinded reviews was consistently good to excellent across four cardiovascular outcomes (chest pain, heart failure, revascularization, MI).
  • Cohen's kappa values ranged from 0.74 to 0.86, indicating substantial to almost perfect agreement.
  • Agreement rates within race and geographic groups were high (83-100%), showing no significant disparities due to unblinding.

Conclusions:

  • Blinding medical record review for race and geography in observational studies may represent an unwarranted expense.
  • The findings suggest that unblinded review can yield reliable outcome ascertainment for certain characteristics, potentially reducing research costs.
Abstract

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