{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,17]],"date-time":"2026-01-17T04:14:04Z","timestamp":1768623244103,"version":"3.49.0"},"reference-count":12,"publisher":"BMJ","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Epidemiol Community Health"],"published-print":{"date-parts":[[1996,12]]},"abstract":"<jats:p>STUDY OBJECTIVES: To evaluate the reliability of data supplied in a case-control study by proxy respondents for cases who were too ill to do so themselves. DESIGN: A hospital based, case-control study of the current use of oral contraceptives (OC) and cardiovascular diseases. Data from \"true\" controls matched to a subset of cases were compared with those supplied by proxy respondents about the true controls. SETTING: Hospitals in 21 centres from Africa, Asia, Europe, and Latin America. PATIENTS AND PARTICIPANTS: For a subset of cases, 403 pairs of controls-one \"true\" and one proxy-were interviewed. \"True\" controls were matched by age, place, and time of admission and were admitted with 1 of 27 permissible diagnoses not associated with OC use. Proxy controls were either relatives or friends of true controls. MAIN RESULTS: Levels of concordance between data from proxy and true controls were high for most variables regarding recent events, including current OC use, but were greatly diminished when detailed information, particularly from the past, was required. Husbands were usually the best proxy, although this was question-specific. The sensitivity and specificity of proxy responses were 93% (95% confidence intervals: 77%, 99%) and 100% (98%, 100%) respectively, for current use of OC. Assuming the misclassification of current OC use by proxy cases is similar to that produced by proxy controls, the estimated impact of using proxy data on risk estimates associated with current OC use was to bias the overall estimate of risk of stroke by less than 3% and the risks of both acute myocardial infarction and venous thromboembolism by less than 1%. CONCLUSIONS: Friends or relatives, and particularly husbands, provided reliable information when used as proxy respondents for young women. The estimated impact of misclassification by proxy respondents on overall risk estimates in the WHO collaborative study was less than that which would have arisen if information from proxy respondents had not been used.<\/jats:p>","DOI":"10.1136\/jech.50.6.674","type":"journal-article","created":{"date-parts":[[2008,11,12]],"date-time":"2008-11-12T15:10:54Z","timestamp":1226502654000},"page":"674-680","source":"Crossref","is-referenced-by-count":20,"title":["Reliability of data from proxy respondents in an international case-control study of cardiovascular disease and oral contraceptives. World Health Organization Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception."],"prefix":"10.1136","volume":"50","author":[{"given":"N R","family":"Poulter","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C L","family":"Chang","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T M","family":"Farley","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M G","family":"Marmot","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[1996,12,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1093\/oxfordjournals.epirev.a036063","article-title":"Proxy respondents in epidemiologic research","volume":"12","author":"Nelson, L.M.; W, Jr, Longstreth; Koepsell, T.D.; Van Belle, G.","year":"1990","unstructured":"Nelson LM, Longstreth W Jr, Koepsell TD, Van Belle G. Proxy respondents in epidemiologic research. Epidemiol Rev 1990;12:71-86.","journal-title":"Epidemiol Rev"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1513","DOI":"10.1016\/0895-4356(95)00516-1","article-title":"WHO Collaborative Study of Cardiovascular Disease and SteroidHormone Contraception. A multinational casecontrol study of cardiovascular disease and steroid hormone contraceptives: description and validation of methods","volume":"48","year":"1995","unstructured":"WHO Collaborative Study of Cardiovascular Disease and SteroidHormone Contraception. A multinational casecontrol study of cardiovascular disease and steroid hormone contraceptives: description and validation of methods. J Clin Epidemiol 1995;48:1513-47.","journal-title":"J Clin Epidemiol"},{"key":"ref_3","first-page":"655","article-title":"Fatal myocardial infarction and the role of OCs","volume":"111","author":"Krueger, D.E.; Ellenberg, S.S.; Bloom, S.","year":"1980","unstructured":"Krueger DE, Ellenberg SS, Bloom S, et al. Fatal myocardial infarction and the role of OCs. AmJrEpidemiol 1980;111: 655-74.","journal-title":"AmJrEpidemiol"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/0010-7824(89)90118-2","article-title":"The reliability of surrogate information about oral contraceptive use, smoking, height and weight collected from men about their wives","volume":"39","author":"Thorogood, M.; Vessey, M.","year":"1989","unstructured":"Thorogood M, Vessey M. The reliability of surrogate information about oral contraceptive use, smoking, height and weight collected from men about their wives. Contraception 1989;39:401-8.","journal-title":"Contraception"},{"key":"ref_5","first-page":"212","article-title":"Statistical methods for rates and proportions","author":"Fleiss, J.L.","year":"1981","unstructured":"Fleiss JL. Statistical methods for rates and proportions. New York; John Wiley & Sons 1981:212-36."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1038\/clpt.1981.18","article-title":"Clinical biostatistics. IV. The biostatistics of concordance","volume":"29","author":"Kramer, M.S.; Feinstein, A.R.","year":"1981","unstructured":"Kramer MS, Feinstein AR. Clinical biostatistics. IV. The biostatistics of concordance. Clin Pharmacol Ther 1981; 29:111-23.","journal-title":"Clin Pharmacol Ther"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1093\/oxfordjournals.aje.a113621","article-title":"Blot WJ. Information available from surrogate respondents in case-control interview studies","volume":"118","author":"Pickle, L.W.; Brown, L.M.","year":"1983","unstructured":"Pickle LW, Brown LM, Blot WJ. Information available from surrogate respondents in case-control interview studies. Am J Epidemiol 1983;118:99-108.","journal-title":"Am J Epidemiol"},{"issue":"2","key":"ref_8","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1093\/aje\/126.2.161","article-title":"Misinterpretation and misuse of the kappa statistic","volume":"126","author":"Maclure, M.; Willett, W.C.","year":"1987","unstructured":"Maclure M, Willett WC. Misinterpretation and misuse of the kappa statistic. Am J Epidemiol 1987;126(2):161-9.","journal-title":"Am J Epidemiol"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/S0140-6736(86)90837-8","article-title":"Statistical methods for assessing agreement between two methods of clinical measurement","volume":"i:","author":"Bland, J.M.; Altman, D.G.","year":"1986","unstructured":"Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;i:307-10.","journal-title":"Lancet"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"408","DOI":"10.1001\/archpsyc.1981.01780290042004","article-title":"Reliability studies of psychiatric diagnosis. Theory and practice","volume":"38","author":"Grove, W.M.; Andreason, N.C.; McDonald-Scott, P.; Keller, M.B.; Shapiro, R.W.","year":"1981","unstructured":"Grove WM, Andreason NC, McDonald-Scott P, Keller MB, Shapiro RW. Reliability studies of psychiatric diagnosis. Theory and practice. Arch Gen Psychiaty 1981;38:408-13.","journal-title":"Arch Gen Psychiaty"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1111\/j.2517-6161.1977.tb01600.x","article-title":"Maximum likelihood from incomplete data via the EM algorithm (with Discussion)","volume":"39","author":"Dempster, A.P.; Laird, N.M.; Rubin, D.B.","year":"1977","unstructured":"Dempster AP, Laird NM, Rubin DB. Maximum likelihood from incomplete data via the EM algorithm (with Discussion). Journal of the Royal Statistical Society, Series B 1977;39: 1-38.","journal-title":"Journal of the Royal Statistical Society, Series B"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"488","DOI":"10.1093\/oxfordjournals.aje.a112408","article-title":"RH Bias due to misclassification in the estimation of relative risk","volume":"105","author":"Copeland, K.T.; McMichael, Checkoway H.; AJ, Holbrook","year":"1977","unstructured":"Copeland KT, Checkoway H. McMichael AJ, Holbrook RH Bias due to misclassification in the estimation of relative risk. 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