Bunin Greta R, Baumgarten Mona, Norman Sandra A, Strom Brian L, Berlin Jesse A
Center for Clinical Epidemiology and Biostatistics and Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
Pharmacoepidemiol Drug Saf. 2005 Aug;14(8):523-30. doi: 10.1002/pds.1130.
We discuss the practical advantages and challenges of sharing controls among two or more concurrently conducted case-control studies.
We conducted two case-control studies, one of breast cancer and the other of endometrial cancer, with overlapping, shared control groups. The studies had overlapping geographic areas, identical telephone questionnaires and biosample collection, and identical age and race eligibility.
Sharing controls reduced the number of potential controls that had to be identified by random-digit dialing by 25% and the number of eligible controls that had to be interviewed by 32%. The cost savings were approximately 2,96,000 dollars, or 7% of the program project that funded the studies.
The disadvantage of sharing controls was the complexity of the design and the additional investigator time required to plan, monitor, and adjust the design. In the situation presented here, the complexities would have been reduced greatly if we had not attempted to frequency match on age in both studies. Generally, sharing controls is likely to work well when strict frequency matching is not required and there is a large overlap of interview questions, other data to be collected, and eligibility criteria among the studies.
我们探讨在两项或多项同时开展的病例对照研究中共享对照组的实际优势与挑战。
我们开展了两项病例对照研究，一项针对乳腺癌，另一项针对子宫内膜癌，采用重叠的共享对照组。两项研究的地理区域重叠，电话调查问卷和生物样本采集相同，年龄和种族纳入标准相同。
共享对照组使通过随机数字拨号确定的潜在对照数量减少了25%，需要访谈的合格对照数量减少了32%。节省的成本约为29.6万美元，占资助该研究的项目计划资金的7%。
共享对照组的缺点是设计复杂，以及在规划、监测和调整设计时需要额外的研究人员时间。在此处呈现的情况下，如果我们没有在两项研究中都尝试按年龄进行频数匹配，复杂性将会大大降低。一般来说，当不需要严格的频数匹配且研究之间的访谈问题、其他要收集的数据以及纳入标准有很大重叠时，共享对照组可能会运作良好。
