Optimising the adult HIV testing services screening tool to predict positivity yield in Zimbabwe, 2022

Abstract

HIV positivity yield declined against increasing testing volumes in Zimbabwe, from 20% (1.65 million tests) in 2011 to 6% (3 million tests) in 2018. A screening tool was introduced to aid testers to identify clients likely to obtain a positive diagnosis of HIV. Consequently, testing volumes declined to 2.3 million in 2019 but positivity declined to 5% prompting the evaluation and validation of the tool to improve its precision in predicting positivity yield. A cross-sectional study was conducted. Sixty-four sites were randomly selected where all reporting clients (18+ years) were screened and tested for HIV. Participant responses and test outcomes were documented and uploaded to excel. Multivariable analysis was used to determine the performance of individual, combination questions and screening criteria to achieve >/ = 90% sensitivity for a new screening tool. We evaluated 13 questions among 7,825 participants and obtained 95.7% overall sensitivity, ranging from 3.9% [(95%CI:2.5,5.9) sharing sharp objects] to 86.8% [(95%CI:83.8,89.5) self-perception of risk] for individual questions. A 5-question tool was developed and validated among 2,116 participants. The best combination (self-perception of risk, partner tested positive, history of ill health, last tested >/ = 3months and symptoms of an STI) scored 94.1% (95%CI:89.4,97.1) sensitivity, 18% reduction in testing volumes and 11 Number Needed to Test (NNT). A screening in criteria that combine previously testing >/ = 3 months with a yes to any of the 4 remaining questions was analysed and sensitivity ranged from 89.9% (95%CI:84.4,94.0) for last tested >/ = 3months and sexual partner positive, to 93.5% (95%CI:88.7,96.7) for last tested >/ = 3months and self-perceived risk We successfully developed, evaluated and validated an HIV screening tool. High sensitivity and the fifth reduction in testing volume were acceptable attributes to enhance testing efficiency and effective limited resource utilisation. Screened out clients will be identified through frequent screening and self-testing options.

Risk Screening Tools Could Potentially Miss HIV-Positive Individuals Who Seek Testing Services: A Secondary Program Data Analysis on the Performance Characteristics of an Adolescent and Adult HIV Risk Screening Tool in Uganda

“…This study and research from other countries [ 12 ] show that screening tools could reduce testing volumes by 24%; hence, apparently saving the cost per HIV-positive case identified, screening in the current study resulted in a marginal increase in positivity rate from 3.71% to 4.5%. Of more concern is the number of clients who were misclassified as ineligible for HIV testing, even though they were HIV positive and they were willing to test for HIV.…”

A Status-Neutral Approach to HIV – Is Targeted Testing Still Relevant South of Sahara?

“…Since 2016, the HTS programme has been pursuing targeted testing as an approach to reduce testing volumes, increase efficiency in HIV testing and enhance the identification of people living with HIV, to enrol them on life-long Antiretroviral Therapy (ART). Eligibility for HIV testing is done using a validated Screening algorithm [17]. In this algorithm, high-risk individuals are offered provider-delivered testing whilst those screened out are offered HIVST kits for self-screen.…”

“…First, patients who were screened for their risk for HIV infection before testing scored a high positivity ratio of 8.5% compared with those who were not screened (5.5%). The risk screening was done using a standardized screening algorithm which is part of standard service delivery by the country, in determining eligibility for an HIV test [17]. Further, the screened patients contributed as high as 75% of the overall positivity obtained, when the calculation combined with those not screened.…”

Understanding Health Worker Perspectives on Risk Screening for HIV Testing—A Qualitative Study from Zimbabwe

“…We applied objectivist and constructivist attributes of the Grounded theory and adapted them to suit our context. This facilitated the application of the comparative methodology that provided systematic guidance for gathering, synthesizing, analyzing, and conceptualizing qualitative data to understand health workers' perspectives on the use of screening tools in HIV testing [6]. The adaptation of the Grounded theory is illustrated in Figure 1.…”

“…During the evaluation and validation exercise, it was anticipated that the positivity yield would decline since no screening was being done (both screened-in and screened-out clients were tested) in contrast with before the exercise when the screening tool guided eligibility for testing. However, it was noted with concern that a positivity yield of 7.53% was documented during the evaluation comparable with 7.68%, which was documented at the same facilities a month before the evaluation exercise [6]. This finding strongly suggested that either the tool was not being routinely utilized as expected, or that the tool was not effective in its determination of eligibility for testing.…”