University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.
University of Ghana, Accra, Ghana.
PLoS One. 2019 Apr 16;14(4):e0215347. doi: 10.1371/journal.pone.0215347. eCollection 2019.
In case-control studies, population controls can help ensure generalizability; however, the selection of population controls can be challenging in environments that lack population registries. We developed a population enumeration and sampling strategy to facilitate use of population controls in a breast cancer case-control study conducted in Ghana.
Household enumeration was conducted in 110 census-defined geographic areas within Ghana's Ashanti, Central, Eastern, and Greater Accra Regions. A pool of potential controls (women aged 18 to 74 years, never diagnosed with breast cancer) was selected from the enumeration using systematic random sampling and frequency-matched to the anticipated distributions of age and residence among cases. Multiple attempts were made to contact potential controls to assess eligibility and arrange for study participation. To increase participation, we implemented a refusal conversion protocol in which initial non-participants were re-approached after several months.
2,528 women were sampled from the enumeration listing, 2,261 (89%) were successfully contacted, and 2,106 were enrolled (overall recruitment of 83%). 170 women were enrolled through refusal conversion. Compared with women enrolled after being first approached, refusal conversion enrollees were younger and less likely to complete the study interview in the study hospital (13% vs. 23%). The most common reasons for non-participation were lack of interest and lack of time.
Using household enumeration and repeated contacts, we were able to recruit population controls with a high participation rate. Our approach may provide a blue-print for others undertaking epidemiologic studies in populations that lack accessible population registries.
在病例对照研究中，人群对照有助于确保研究结果的普适性；然而，在缺乏人群登记系统的环境中，选择人群对照可能具有挑战性。我们制定了一种人群计数和抽样策略，以方便在加纳进行的乳腺癌病例对照研究中使用人群对照。
在加纳的阿散蒂、中部、东部和大阿克拉地区的 110 个普查定义的地理区域进行了家庭计数。从计数中使用系统随机抽样和频率匹配的方法，从潜在对照（年龄在 18 至 74 岁之间、从未被诊断患有乳腺癌的女性）中选择了一个人群对照池，以匹配病例中年龄和居住地的预期分布。我们多次尝试联系潜在的对照者，以评估其资格并安排参与研究。为了提高参与率，我们实施了拒绝转换方案，即在几个月后再次联系最初拒绝的非参与者。
从计数清单中抽取了 2528 名女性，成功联系到 2261 名（89%），并招募了 2106 名（总体招募率为 83%）。通过拒绝转换招募了 170 名女性。与首次联系后参与的女性相比，拒绝转换招募的女性年龄更小，在研究医院完成研究访谈的可能性更小（13%比 23%）。不参与的最常见原因是缺乏兴趣和缺乏时间。
我们通过家庭计数和反复联系，成功招募了具有高参与率的人群对照。我们的方法可能为在缺乏可访问人群登记系统的人群中进行流行病学研究的其他人提供了蓝图。
