Southern Africa Medical Unit, Médecins Sans Frontiéres, Cape Town, South Africa.
Médecins Sans Frontiéres, Kinshasa, Democratic Republic of Congo.
PLoS One. 2020 Apr 3;15(4):e0230453. doi: 10.1371/journal.pone.0230453. eCollection 2020.
In sub-Saharan Africa, a third of people starting antiretroviral therapy and majority of patients returning to HIV-care after disengagement, present with advanced HIV disease (ADH), and are at high risk of mortality. Simplified and more affordable point-of-care (POC) diagnostics are required to increase access to prompt CD4 cell count screening for ambulatory and asymptomatic patients. The Visitect CD4 Lateral Flow Assay (LFA) is a disposable POC test, providing a visually interpreted result of above or below 200 CD4cells/mm3. This study evaluated the diagnostic performance of this index test.
Consenting patients above 18years of age and eligible for CD4 testing were enrolled in Nsanje district hospital (Malawi), Gutu mission hospital (Zimbabwe) and Centre hopitalier de Kabinda (DRC). A total of 708 venous blood samples were tested in the index test and in the BD FACSCount assay (reference test method) in the laboratories (Phase 1) to determine diagnostic accuracy. A total of 433 finger-prick (FP) samples were tested on the index test at POC by clinicians (Phase 2) and a self-completed questionnaire was administered to all testers to explore usability of the index test.
Among 708 patients, 67.2% were female and median CD4 was 297cells/mm3. The sensitivity of the Visitect CD4 LFA using venous blood in the laboratory was 95.0% [95% CI: 91.3-97.5] and specificity was 81.9% [95% CI: 78.2-85.2%]. Using FP samples, the sensitivity of the Visitect CD4 LFA was 98.3% [95% CI: 95.0-99.6] and specificity was 77.2% [95% CI: 71.6-82.2%]. Usability of the Visitect CD4 LFA was high across the study sites with 97% successfully completed tests. Due to the required specific multiple incubation and procedural steps during the Visitect CD4 LFA testing, few health workers (7/26) were not confident to manage testing whilst multi-tasking in their clinical work.
Visitect CD4 LFA is a promising test for decentralized CD4 screening in resource-limited settings, without access to CD4 testing and and it can trigger prompt management of patients with AHD. Lay health cadres should be considered to conduct Visitect CD4 LFA testing in PHCs as well as coordinating all other POC quality assurance.
在撒哈拉以南非洲，三分之一开始接受抗逆转录病毒治疗的人以及大多数重新回到艾滋病毒护理的人，都患有晚期艾滋病（ADH），并且有很高的死亡率。需要简化和更经济实惠的即时护理（POC）诊断方法，以增加对门诊和无症状患者进行即时 CD4 细胞计数筛查的机会。Visitect CD4 侧向流动检测（LFA）是一种一次性 POC 检测方法，可提供 200 个以上或以下的 CD4 细胞/mm3 的视觉解释结果。本研究评估了该指标检测的诊断性能。
在 Nsanje 区医院（马拉维）、Gutu 传教士医院（津巴布韦）和 Centre hopitalier de Kabinda（刚果民主共和国），同意并符合 CD4 检测条件的 18 岁以上患者被纳入研究。共 708 份静脉血样本在实验室中进行了指数检测和 BD FACSCount 检测（参考检测方法）（第 1 阶段），以确定诊断准确性。共有 433 份指尖（FP）样本在第 2 阶段由临床医生在 POC 上进行了指数检测，所有检测人员都完成了一份自我评估问卷，以探讨该指数检测的可用性。
在 708 名患者中，67.2%为女性，中位 CD4 为 297 个细胞/mm3。在实验室中使用静脉血时，Visitect CD4 LFA 的灵敏度为 95.0%[95%CI：91.3-97.5]，特异性为 81.9%[95%CI：78.2-85.2%]。使用 FP 样本时，Visitect CD4 LFA 的灵敏度为 98.3%[95%CI：95.0-99.6]，特异性为 77.2%[95%CI：71.6-82.2%]。Visitect CD4 LFA 在整个研究地点的可用性都很高，97%的测试都成功完成。由于 Visitect CD4 LFA 检测需要特殊的多次孵育和操作步骤，因此很少有卫生工作者（7/26）有信心在临床工作中同时进行多项任务时管理检测。
Visitect CD4 LFA 是资源有限环境中用于分散式 CD4 筛查的有前途的检测方法，无法进行 CD4 检测，可及时治疗患有 ADH 的患者。应考虑让非专业卫生工作者在初级保健中心进行 Visitect CD4 LFA 检测，并协调所有其他即时护理质量保证工作。
