Mitchell Alice M, Kline Jeffrey A
Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC, USA.
Acad Emerg Med. 2008 Mar;15(3):225-30. doi: 10.1111/j.1553-2712.2008.00066.x.
To determine population characteristics, outcomes, and reasons for unsuccessful enrollment among potential study subjects approached for written, informed consent in a minimal-risk emergency department (ED) study. The authors hypothesized that the prevalence of venous thromboembolism (VTE) would be lower among study participants and that medical acuity and refusal to provide a blood sample would be the most common reasons for nonparticipation.
The authors requested prospective, written, informed consent for a blood sample and follow-up from consecutive ED patients undergoing evaluation for pulmonary embolism (PE) and recorded spontaneously stated reasons for refusal. VTE was diagnosed or excluded using a combination of D-dimer testing and selective computed tomography (CT) angiography of the chest with venography of the lower extremities. The primary outcome was defined by the number of CT scans positive for VTE among ED patients evaluated for PE.
Over 16 weeks, 260 of 287 (91%, 95% confidence interval [CI] = 87 to 94%) eligible patients were approached and consent was obtained from 183 patients (64%, 95% CI = 58% to 69%). The prevalence of VTE was 6% among participants and 13% among nonparticipants (95% CI [of the difference] = 1% to 15%). The proportions of African Americans, uninsured, and Medicaid patients were significantly higher among nonparticipants. No significant differences were found in the proportions of nonparticipants who disliked or distrusted research or desired financial reimbursement, compared to those not enrolled due to medical acuity or refused a blood sample.
These data implicate the written, informed consent process as a significant source of bias on estimated disease prevalence.
在一项低风险急诊科（ED）研究中，确定在寻求书面知情同意的潜在研究对象中，人群特征、研究结果以及未成功入组的原因。作者假设静脉血栓栓塞症（VTE）在研究参与者中的患病率会更低，并且病情严重程度以及拒绝提供血样将是最常见的未参与原因。
作者要求对连续接受肺栓塞（PE）评估的急诊科患者进行前瞻性书面知情同意，以获取血样并进行随访，并记录自发陈述的拒绝原因。使用D - 二聚体检测以及胸部选择性计算机断层扫描（CT）血管造影结合下肢静脉造影来诊断或排除VTE。主要结局由接受PE评估的急诊科患者中VTE阳性的CT扫描数量来定义。
在16周内，287名符合条件的患者中有260名（91%，95%置信区间[CI]=87%至94%）被纳入研究，183名患者（64%，95%CI = 58%至69%）获得了同意。参与者中VTE的患病率为6%，未参与者中为13%（差异的95%CI = 1%至15%）。未参与者中非洲裔美国人、未参保者和医疗补助患者的比例显著更高。与因病情严重程度未入组或拒绝提供血样的患者相比，在不喜欢或不信任研究或期望获得经济补偿的未参与者比例方面未发现显著差异。
这些数据表明书面知情同意过程是估计疾病患病率时偏差的一个重要来源。
