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reporting_bias_in_abortion-breast_cancer_studies [2015/07/28 19:19] marri |
reporting_bias_in_abortion-breast_cancer_studies [2022/03/23 16:14] (current) |
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+ | ==========Reporting Bias in Abortion-Breast Cancer Studies========== | ||
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+ | The most common argument against retrospective studies affirming the [[abortion-breast_cancer_link|abortion-breast cancer link]] is recall bias: the theory that cases who have breast cancer, will be more likely to report having had abortions than (usually healthy) controls. Neither the 1991 Lindefors Harris study nor the [[studies_on_the_abortion-breast_cancer_link|1996 Rookus study]] are sufficient evidence for this theory. The results of retrospective or case-control studies must not be dismissed out of hand. | ||
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+ | =====1. 1991 Lindefors Harris Study===== | ||
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+ | The most quoted study((Britt-Marie Lindefors Harris, Gunnar Eklund, Hans-Olov Adami, and Olav Meirik, “Response Bias in a Case-control Study: Analysis Utilizing Comparative Data Concerning Legal Abortions from Two Independent Swedish Studies,” //American Journal of Epidemiology// | ||
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+ | However, their [[common_problems_in_abortion-breast_cancer_studies|findings are an insufficient basis]] for this conclusion. The interviews referenced were conducted at home. Interviews conducted in participants’ homes will not be comparable to those conducted in clinical environments and will be disposed to bias and underreporting (which will not likely differ between cases and controls). | ||
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+ | Furthermore, | ||
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+ | The difference in the percentage of cases and controls underreporting their registered abortions amounts to undisclosed abortions on the part of //two or fewer cases//. (Among cases, the error in the registry is larger than the error introduced by underreporting. See the table below.) Furthermore, | ||
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+ | **__Breakdown of Induced Abortions as (un)Registered and (un)Reported in the 1991 Lindefors Harris Study__** | ||
+ | ^24 cases had abortion in the registry ^26 cases reported abortions in their interview ^ | ||
+ | |5 //did not// disclose registered abortions | 19 //did// disclose registered abortions |7 disclosed // | ||
+ | ^59 controls had abortions in the registry ^44 controls reported abortions in their interview ^ | ||
+ | |16 //did not// disclose registered abortions |43 //did// disclose registered abortions |1 disclosed an // | ||
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+ | =====2. 1996 Rookus study===== | ||
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+ | The authors of this study in Holland((Matti A. Rookus, Flora E. van Leeuwen, “Induced Abortion and Risk for Breast Cancer: Reporting (Recall) Bias in a Dutch Case-Control Study,” //Journal of the National Cancer Institute// 88, no. 23 (1996): 1759-1764. | ||
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+ | This entry draws heavily from [[http:// | ||
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+ | The authors attribute the gap in the risk associated with induced abortion between the more and less religious regions to area religiosity; | ||
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+ | [[common_problems_in_abortion-breast_cancer_studies|Recall bias]] is predicated on the assumption that controls are more likely to obscure induced abortion history than cases, yet 12 percent more controls than cases agreed to participate in the study (the authors state that “[a] small nonresponse study among case subjects suggested that the majority of nonresponders had not been informed of the study by their doctors and thus had not been able to consider participation”). | ||
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+ | Furthermore, | ||
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+ | The authors did not include controls for all known breast cancer risk factors; hence, there is no need for the assertion of reporting bias as it is put forward but not substantiated by the authors. The differing risk found for induced abortion in the more religious and less religious regions may be due to any number of factors. | ||