Abortion and breast cancer: a case-control record linkage study
Abortion and breast cancer: a case-control record linkage study
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DOI：
10.1136/jech.55.5.336
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发表时间：
2001-05-01
影响因子：
6.3
通讯作者：
Yeates, D
中科院分区：
文献类型：
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作者：
Goldacre, MJ;Kurina, LM;Yeates, D
方法我们进行了一项嵌套式病例对照研究，使用来自牛津记录连锁数据集的链接、匿名数据。我们以这种方式研究疾病关联的方法在其他地方有详细描述。对1968-1998年(即1967年《堕胎法》允许堕胎后)的9项数据进行了分析，其中包括国家医疗服务体系(NHS)住院记录(包括日间病例)和死亡证明的统计摘要。“病例”是乳腺癌妇女的记录(n=28 616)。“对照”是其他各种情况(主要是轻微的)内科和外科住院的妇女的记录(n=325 456)。对记录进行分析，比较病例和对照，以确定以前住院的编码为人工流产、自然流产或未指明为引产或自发流产的住院病例。对堕胎进行编码是很常见的，而不限定堕胎是诱导的还是自发的。病例和对照按年龄(五年组)、病例或对照事件发生的年份和居住地进行分层。尽管社会阶层数据的记录不完整，但对社会阶层的有限分层是可能的。结果总体而言，乳腺癌女性既往流产的发生率比对照组略低(表1)。我们想知道，较低的失业率是否可能是与社会阶层混为一谈的结果；但它在每个社会阶层中都存在。无论是对于所有堕胎还是人工流产，观察到的病例与预期病例的比率都不会随着时间的推移而增加，如果堕胎是乳腺癌的原因，这一点是可以预期的。当人工流产与其他堕胎进行比较时，观察到的病例与预期病例的比率在总体上(表1)或在个别时间段没有显著差异。
MethodsWe undertook a nested case-control study using linked, anonymised data from the Oxford record linkage dataset. Our methods for studying disease associations in this way are described in detail elsewhere. 9 Data were analysed from 1968–1998 (that is, after the Abortion Act of 1967 which liberalised abortion) and comprise statistical abstracts of records of National Health Service (NHS) hospital admissions (including day cases) and death certificates.“Cases” were records of women with breast cancer (n= 28 616).“Controls” were records of women with a wide range of other, mainly minor, medical and surgical admissions (n= 325 456). Records were analysed, comparing cases and controls, to identify prior hospital admissions coded as induced abortion, spontaneous abortion, or abortion unspecified as induced or spontaneous. It was common for abortions to be coded without qualification of whether they were induced or spontaneous. Cases and controls were stratified by age (in five year bands), year of occurrence of case or control event, and place of residence. Limited stratification for social class was possible although the recording of social class data was incomplete.ResultsOverall, previous abortion was slightly less common in women with breast cancer than in controls (table 1). We wondered if the lower rate might result from confounding with social class; but it was found in each social class stratum. The ratio of observed to expected cases did not increase over time either for all abortions or for induced abortions, as would be expected if abortions were a cause of breast cancer. When induced abortions were compared with other abortions, the ratios of observed to expected cases were not significantly different overall (table 1) or at individual time periods.