Point-of-care testing of HIV refers to the practice undertaken by healthcare professionals at the time of testing outside of a designated laboratory. The standard methods of HIV testing, enzyme linked immunosorbent assay (ELISA) or Western blot with confirmatory testing, can take several days for result availability. A significant proportion of individuals who agree to undergo HIV serologic testing do not return to the HIV testing site to receive their test results. POC testing of HIV attempts to address delay in detection of HIV status by providing preliminary antibody results. POC tests can be most useful in resource limited settings (RLS) or outreach settings where there is lack of well-trained laboratory technicians, poor physical infrastructure, extremes of climate, and lack of uninterrupted power supply, all of which impact the use of laboratory technologies. Point-of-care testing has been shown to reduce patient loss to follow-up and increase access to antiretroviral therapy.
Rapid test devices (RTDs) are typically capillary flow tests for use on whole blood (e.g., fingerprick), plasma, or oral fluid. HIV test kits are designed for HIV antibody and antigen detection. The results can be delivered within 20 minutes after the specimen has been taken. The results are available within a single consultation. The rapid turnaround time associated with its use can guide urgent decision making. This makes it suitable for use in targeted clinical scenarios where the immediate administration of antiretroviral drugs is recommended to reduce the risk of transmission or in cases where the patient’s management may be altered by the availability of a reactive test result.
Access to antiretroviral therapy (ART) has increased dramatically over the past decade in Indonesia. Successful management of HIV requires patients receiving ART to be monitored routinely to assess treatment efficacy and detect treatment failure due to drug resistance. The standard of care to monitor ART is quantitative viral load testing based on plasma HIV RNA concentration. POC test for CD4 count could help clinicians to decide when to start antiretroviral treatment, and a POC test for viral load would be of great value in identifying treatment failure and the need for second-line treatment. These devices could rapidly and accurately identify CD4 counts with minimal operator training, infrastructural setup, and with less cost than standard laboratory-based equipment. Several CD4 POCT analysers can give CD4 count in 20 minutes from a finger stick or venous sample.
HIV viral load testing is the most accurate method to evaluate the response of ART on HIV infected patients. It is considered as gold standard to monitor response therapy and predict clinical prognosis of patients on ART. The threshold used to detect the failure to ART is 1000 virus copies/mL. The nucleic acid based tests detect and measure viral RNA. Several POC devices for viral load are currently available and in the pipeline.
Diagnosing HIV infection in infants early will be very beneficial in reducing the mortality of infants due to the HIV infection. The maternal antibodies present in the system of infants makes the antibody test undesirable for diagnosing HIV in infants less than the age of 18 months. The detection of viral components are required for early infant diagnosis and this can include viral capsid p24 antigen, cell free RNA or viral DNA incorporated into the host detection. The current p24 immunoassays show more sensitivity than the previously used p24. However, similar to nucleic acid amplification-based assays, p24 immunoassays require specialised equipment and skilled technicians to perform the test. In order to perform these tests in resource limited settings, early infant diagnosis rapid tests are required.
In Indonesia, POCT in HIV management has been used for several years. HIV rapid testing, POCT CD4 and VL has been used in all 34 provinces in Indonesia. HIV rapid testing used for initial screening has been used in primary healthcare, while CD4 and VL POCT placed in district hospital or laboratory to cover the testing reference from the whole area.
Rapidly scaling up point-of-care testing without simultaneously building the capacity of quality assurance is counterproductive if service providers are unable to guarantee adherence to minimum quality standards with accurate and reliable results. We found several challenges in implementing POC Testing. In contrast to standard laboratory-based HIV testing, the healthcare workers in the POC setting assume responsibility for specimen collection, testing, and counselling of the patient. Appropriate training on the use of kits, reading of results, detection of errors, quality assurance, counselling, and regular assessment of staff who will be performing POC testing is required for providing point-of-care testing.
RTDs are generally satisfactory for the detection of uncomplicated HIV infection (or its absence) but are less sensitive than lab-based ELISAs and automated systems for detecting early infections (seroconversion). Also, specificity of RTDs is lower than conventional ELISAs although it can be improved by immediate repeat of all RTD positives.
A variety of rapid tests for diagnosing HIV in resource limited settings are commercially available. All the approved HIV POC tests should have a sensitivity and specificity matching the ELISA kits that are used in laboratories. POC devices have in-built internal quality controls to monitor in real time the performance of an instrument and, to some extent, the user. External quality assessment (EQA), often used interchangeably with proficiency testing, challenges the testing environment and allows for an external expert body to examine the processes and provide remedial action. The three components of an effective EQA laboratory programme are site supervision, retesting of specimens, and proficiency testing. Proficiency testing is the most widely-used approach to monitor the performance of the test used and the quality of testing. It involves blinded control material, meant to mimic patient specimens, sent from a reference laboratory to the testing site and results sent back for scoring.
Indonesia’s Ministry of Health is currently providing EQA for rapid HIV test organised by provincial reference laboratory, while CD4 and VL EQA are centrally organised. CD4 EQA is provided by COE CD4 EQAS – Thailand, and QASI – Canada and VL from NRL – Australia.