Comparison of Medicare claims versus physician adjudication for identifying stroke outcomes in the Women's Health Initiative.
BACKGROUND AND PURPOSE
Many studies use medical record review for ascertaining outcomes. One large, longitudinal study, the Women's Health Initiative (WHI), ascertains strokes using participant self-report and subsequent physician review of medical records. This is resource-intensive. Herein, we assess whether Medicare data can reliably assess stroke events in the WHI.


METHODS
Subjects were WHI participants with fee-for-service Medicare. Four stroke definitions were created for Medicare data using discharge diagnoses in hospitalization claims: definition 1, stroke codes in any position; definition 2, primary position stroke codes; and definitions 3 and 4, hemorrhagic and ischemic stroke codes, respectively. WHI data were randomly split into training (50%) and test sets. A concordance matrix was used to examine the agreement between WHI and Medicare stroke diagnosis. A WHI stroke and a Medicare stroke were considered a match if they occurred within ±7 days of each other. Refined analyses excluded Medicare events when medical records were unavailable for comparison.


RESULTS
Training data consisted of 24 428 randomly selected participants. There were 577 WHI strokes and 557 Medicare strokes using definition 1. Of these, 478 were a match. With regard to algorithm performance, specificity was 99.7%, negative predictive value was 99.7%, sensitivity was 82.8%, positive predictive value was 85.8%, and κ=0.84. Performance was similar for test data. Whereas specificity and negative predictive value exceeded 99%, sensitivity ranged from 75% to 88% and positive predictive value ranged from 80% to 90% across stroke definitions.


CONCLUSIONS
Medicare data seem useful for population-based stroke research; however, performance characteristics depend on the definition selected.
['Lakshminarayan|Kamakshi|K|', 'Larson|Joseph C|JC|', 'Virnig|Beth|B|', 'Fuller|Candace|C|', 'Allen|Norrina Bai|NB|', 'Limacher|Marian|M|', 'Winkelmayer|Wolfgang C|WC|', 'Safford|Monika M|MM|', 'Burwen|Dale R|DR|']
D000368:Aged D000465:Algorithms D002545:Brain Ischemia D003627:Data Interpretation, Statistical D005260:Female D005500:Follow-Up Studies D006760:Hospitalization D006801:Humans D020300:Intracranial Hemorrhages D008137:Longitudinal Studies D006278:Medicare D008875:Middle Aged D010820:Physicians D015203:Reproducibility of Results D020521:Stroke D011795:Surveys and Questionnaires D016896:Treatment Outcome D014481:United States D016387:Women's Health
Medicare stroke validation studies