ACCURACY OF REPORTED FAMILY HISTORY OF HEART-DISEASE - THE IMPACT OF DONT KNOW RESPONSES

Background: Usual 'Yes/No' definitions of a family history of heart di sease do not allow for 'Don't know' responses. In some families, miscl assification of family history may result if these are not considered. Aims: To study the accuracy of family history reporting and the impac t of 'Don't know' responses. Methods: We compared reported family hist ory of coronary heart disease (CHD) and cancer among 360 deceased rela tives of 59 probands with 'gold standard' diagnoses recorded on offici al death certificates. Results: For first degree relatives, sensitivit y of reporting was 81% for CHD, 86% for any heart disease and 60% for cancer, while for second degree relatives, sensitivity was 73%, 69% an d 90%, respectively. When 'Don't know' responses were classified as 'N o', sensitivity in first degree relatives was not affected, but in sec ond degree relatives, it fell to 49%, 41% and 60%, respectively. Speci ficities were unchanged. These data show that in families where inform ation beyond first degree relatives is considered, failing to account for 'Don't know' responses is likely to lead to misclassification of f amily history of CHD.