USE OF SURROGATE RESPONDENTS IN STUDIES OF STROKE AND DEMENTIA

A study was performed to determine the misclassification of informatio n on exposure when surrogate informants are interviewed. Information f rom nondementia patients admitted to a geriatric ward was compared wit h that obtained from the patients' family members or friends (informan ts). Thirty seven patients were recruited (17 with current or previous stroke, and 20 no history of stroke). Information on past medical and family history, cigarette smoking and alcohol consumption was collect ed using a questionnaire that was administered independently to patien ts and informants. For nonstroke patients, agreement on smoking and al cohol consumption at different ages was generally good. Informants rep orted slightly lower smoking and alcohol intake than patients: 1.3 fev er total pack-years (95% CI, -3.8, +/- 6.5) and 2.7 fewer units/week ( 95% CI, -1.5, +6.9), respectively. For stroke patients, informants ten ded to report a greater smoking consumption at all ages, and a slightl y higher alcohol consumption. Informants reported an excess of 7.4 tot al pack-years (95% CI, -1.2, +16.0) and 2.19 units/week (95% CI, -1.0, +5.3). Agreement for medical history was good, except for hypertensio n. There was poor agreement for family medical history. The impact of misclassification is discussed.