Optimizing HIV testing services in sub-Saharan Africa: cost and performance of verification testing with HIV self-tests and tests for triage

Costs of distributing HIV self-testing kits in Eswatini through community and workplace models

BACKGROUND

This study evaluates the implementation and running costs of an HIV self-testing (HIVST) distribution program in Eswatini. HIVST kits were delivered through community-based and workplace models using primary and secondary distribution. Primary clients could self-test onsite or offsite. This study presents total running economic costs of kit distribution per model between April 2019 and March 2020, and estimates average cost per HIVST kit distributed, per client self-tested, per client self-tested reactive, per client confirmed positive, and per client initiating antiretroviral therapy (ART).

METHODS

Distribution data and follow-up phone interviews were analysed to estimate implementation outcomes. Results were presented for each step of the care cascade using best-case and worst-case scenarios. A top-down incremental cost-analysis was conducted from the provider perspective using project expenditures. Sensitivity and scenario analyses explored effects of economic and epidemiological parameters on average costs.

RESULTS

Nineteen thousand one hundred fifty-five HIVST kits were distributed to 13,031 individuals over a 12-month period, averaging 1.5 kits per recipient. 83% and 17% of kits were distributed via the community and workplace models, respectively. Clients reached via the workplace model were less likely to opt for onsite testing than clients in the community model (8% vs 29%). 6% of onsite workplace testers tested reactive compared to 2% of onsite community testers. Best-case scenario estimated 17,458 (91%) clients self-tested, 633 (4%) received reactive-test results, 606 (96%) linked to confirmatory testing, and 505 (83%) initiated ART. Personnel and HIVST kits represented 60% and 32% of total costs, respectively. Average costs were: per kit distributed US$17.23, per client tested US$18.91, per client with a reactive test US$521.54, per client confirmed positive US$550.83, and per client initiating ART US$708.60. Lower rates for testing, reactivity, and linkage to care in the worst-case scenario resulted in higher average costs along the treatment cascade.

CONCLUSION

This study fills a significant evidence gap regarding costs of HIVST provision along the client care cascade in Eswatini. Workplace and community-based distribution of HIVST accompanied with effective linkage to care strategies can support countries to reach cascade objectives.

Using signal-to-cutoff ratios of HIV screening assay to predict HIV infection

BACKGROUND

The sensitivity of HIV screening assays often leads to a high rate of false-positive results, requiring retests and confirmatory tests. This study aimed to analyze the capability of signal-to-cutoff (S/CO) ratios of HIV screening assay to predict HIV infection.

METHODS

A retrospective study on the HIV screening-positive population was performed at Zhongshan Hospital, Xiamen University, the correlation between HIV screening assay S/CO ratios and HIV infection was assessed, and plotted Receiver Operating Characteristic (ROC) curves were generated to establish the optimal cutoff value for predicting HIV infection.

RESULTS

Out of 396,679 patients, 836 were confirmed to be HIV-infected, with an HIV prevalence of 0.21%. The median S/CO ratios in HIV infection were significantly higher than that in non-HIV infection (296.9 vs. 2.41, P < 0.001). The rate of confirmed HIV infection was increased with higher S/CO ratios in the screening assay. The ROC curve based on the HIV screening assay S/CO ratio achieved a sensitivity of 93.78% and a specificity of 93.12% with an optimal cutoff value of 14.09. The area under the ROC curve was 0.9612. Further analysis of the ROC curve indicated that the S/CO ratio thresholds yielding positive predictive values of 99%, 99.5%, and 100% for HIV infection were 26.25, 285.7, and 354.5, respectively.

CONCLUSION

Using HIV screening assay S/CO ratio to predict HIV infection can largely reduce necessitating retests and confirmatory tests. Incorporating the S/CO ratio into HIV testing algorithms can have significant implications for medical and public health practices.

Predictors of HIV testing among women experiencing intimate partner violence in the Central Region of Ghana

HIV testing, which is important for the control of the HIV pandemic, has been hampered by several factors including Intimate Partner Violence (IPV), resulting in low uptake. This study sought to determine the predictors of HIV testing among women experiencing IPV. Secondary analysis of data generated from a cross-sectional mixed-method unmatched cluster-randomized controlled trial designed to evaluate a multi-faceted community intervention to reduce the incidence of IPV in Ghana was done (N = 2000). Logistic regressions were performed to determine the predictors of HIV testing among women experiencing IPV, using the trial baseline data. The prevalence of HIV testing among women exposed to IPV in the study setting was 42.4%. Less than a third of the respondents (30.2%) had ever used condom and 96.6% had unemployed partners. Age, educational attainment, employment, residence and condom use were found to be significant predictors of HIV testing among women experiencing IPV. Women aged 25-39 years were more than twice as likely to test for HIV (AOR:2.41; 95%CI:1.45-4.02) than those above 45 years. Women with formal education (Junior-High-AOR:2.10; 95%CI:1.42-3.12; Senior-High-AOR:3.87; 95%CI:2.07-7.26); who had ever used condom (AOR:1.42; 95%CI:1.05-1.93); those reporting life satisfaction (AOR:1.44; 95%CI:1.08-1.92); and coastal residents (AOR:1.97; 95%CI:1.45-2.67) were more likely to test for HIV than those who did not and inland residents. However, employed women (AOR:0.66; 95%CI:0.45-0.96) were less likely to test for HIV than unemployed women. Less than half of the women exposed to IPV had tested for HIV. Socioeconomic disadvantages related to age, education, employment, residence and life satisfaction predicted HIV testing among women exposed to IPV. Considering the vulnerability of women experiencing IPV to HIV infection, strategies to improve uptake of HIV testing must tackle contextual socioeconomic factors that hinder access to services.

Evaluating Point-of-Care Nucleic Acid Tests in Adult Human Immunodeficiency Virus Diagnostic Strategies: A Côte d'Ivoire Modeling Analysis

BACKGROUND

The World Health Organization (WHO) human immunodeficiency virus (HIV) diagnostic strategy requires 6 rapid diagnostic tests (RDTs). Point-of-care nucleic acid tests (POC NATs) are costlier, less sensitive, but more specific than RDTs.

METHODS

We simulated a 1-time screening process in Côte d'Ivoire (CI; undiagnosed prevalence: 1.8%), comparing WHO- and CI-recommended RDT-based strategies (RDT-WHO, RDT-CI) and an alternative: POC NAT to resolve RDT discordancy (NAT-Resolve). Costs included assays (RDT: $1.47; POC NAT: $27.92), antiretroviral therapy ($6-$22/month), and HIV care ($27-$38/month). We modeled 2 sensitivity/specificity scenarios: high-performing (RDT: 99.9%/99.1%; POC NAT: 95.0%/100.0%) and low-performing (RDT: 91.1%/82.9%; POC NAT: 93.3%/99.5%). Outcomes included true-positive (TP), false-positive (FP), true-negative (TN), or false-negative (FN) results; life expectancy; costs; and incremental cost-effectiveness ratios (ICERs: $/year of life saved [YLS]; threshold ≤$1720/YLS [per-capita gross domestic product]).

RESULTS

Model-projected impacts of misdiagnoses were 4.4 years lost (FN vs TP; range, 3.0-13.0 years) and a $5800 lifetime cost increase (FP vs TN; range, $590-$14 680). In the high-performing scenario, misdiagnoses/10 000 000 tested were lowest for NAT-Resolve vs RDT-based strategies (FN: 409 vs 413-429; FP: 14 vs 21-28). Strategies had similar life expectancy (228 months) and lifetime costs ($220/person) among all tested; ICERs were $3450/YLS (RDT-CI vs RDT-WHO) and $120 910/YLS (NAT-Resolve vs RDT-CI). In the low-performing scenario, misdiagnoses were higher (FN: 22 845-30 357; FP: 83 724-112 702) and NAT-Resolve was cost-saving.

CONCLUSIONS

We projected substantial clinical and economic impacts of misdiagnoses. Using POC NAT to resolve RDT discordancy generated the fewest misdiagnoses and was not cost-effective in high-performing scenarios, but may be an important adjunct to existing RDT-based strategies in low-performing scenarios.

HIV self-testing in adolescents living in Sub-Saharan Africa

Less than 20% of African adolescents aged 10-19 years are aware of their HIV status, whereas HIV screening remains the gateway to care and while AIDS has become the leading cause of death among adolescents in Sub-Saharan Africa. According to the UNAIDS target, scalable HIV testing strategies specific to various age groups, populations, and geographical areas must be implemented to end the AIDS epidemic by 2030. Many African countries have implemented policies supporting HIV self-testing (HIVST). Evidence of practicability and efficiency of HIVST in Sub-Saharan Africa settings has been reported, including HIVST data among adolescents. Adapted strategies of HIVST are urgently needed to promote HIV testing among adolescents living in sub-Saharan Africa.

Optimizing HIV testing services in sub-Saharan Africa: cost and performance of verification testing with HIV self-tests and tests for triage

INTRODUCTION

Strategies employing a single rapid diagnostic test (RDT) such as HIV self-testing (HIVST) or "test for triage" (T4T) are proposed to increase HIV testing programme impact. Current guidelines recommend serial testing with two or three RDTs for HIV diagnosis, followed by retesting with the same algorithm to verify HIV-positive status before anti-retroviral therapy (ART) initiation. We investigated whether clients presenting to HIV testing services (HTS) following a single reactive RDT must undergo the diagnostic algorithm twice to diagnose and verify HIV-positive status, or whether a diagnosis with the setting-specific algorithm is adequate for ART initiation.

METHODS

We calculated (1) expected number of false-positive (FP) misclassifications per 10,000 HIV negative persons tested, (2) positive predictive value (PPV) of the overall HIV testing strategy compared to the WHO recommended PPV ≥99%, and (3) expected cost per FP misclassified person identified by additional verification testing in a typical low-/middle-income setting, compared to the expected lifetime ART cost of $3000. Scenarios considered were as follows: 10% prevalence using two serial RDTs for diagnosis, 1% prevalence using three serial RDTs, and calibration using programmatic data from Malawi in 2017 where the proportion of people testing HIV positive in facilities was 4%.

RESULTS

In the 10% HIV prevalence setting with a triage test, the expected number of FP misclassifications was 0.86 per 10,000 tested without verification testing and the PPV was 99.9%. In the 1% prevalence setting, expected FP misclassifications were 0.19 with 99.8% PPV, and in the Malawi 2017 calibrated setting the expected misclassifications were 0.08 with 99.98% PPV. The cost per FP identified by verification testing was $5879, $3770, and $24,259 respectively. Results were sensitive to assumptions about accuracy of self-reported reactive results and whether reactive triage test results influenced biased interpretation of subsequent RDT results by the HTS provider.

CONCLUSIONS

Diagnosis with the full algorithm following presentation with a reactive triage test is expected to achieve PPV above the 99% threshold. Continuing verification testing prior to ART initiation remains recommended, but HIV testing strategies involving HIVST and T4T may provide opportunities to maintain quality while increasing efficiency as part of broader restructuring of HIV testing service delivery.