Comparison of methods for classifying Hispanic ethnicity in a population-based cancer registry

The accuracy of ethnic classification can substantially affect ethnic-speci fic cancer statistics. In the Greater Bay Area Cancer Registry, which is pa rt of the Surveillance, Epidemiology, and End Results (SEER) Program and of the statewide California Cancer Registry, Hispanic ethnicity is determined by medical record review and by matching to surname lists. This study comp ared these classification methods with self-report. Ethnic self-identificat ion was obtained by surveying 1,154 area residents aged 20-89 years who wer e diagnosed with cancer in 1990 and were reported to the registry as being Hispanic or White non-Hispanic, Predictive value positive, sensitivity, and relative bias were used to assess the accuracy of Hispanic classification by medical record and surname. Among those persons classified as Hispanic b y either or both of these sources, only two-thirds agreed (predictive value positive = 66%), and many self-identified Hispanics were classified incorr ectly (sensitivity = 68%). Classification based on either medical record or surname alone had a lower sensitivity (59% and 61%, respectively) but a hi gher predictive value positive (77% and 70%, respectively). Ethnic classifi cation by medical record alone resulted in an underestimate of Hispanic can cer cases and incidence rates. Bias was reduced when medical records and su rnames were used together to classify cancer cases as Hispanic.