Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 28, Num. 4, 2010, pp. 295-298

Indian Journal of Medical Microbiology, Vol. 28, No. 4, October-December, 2010, pp. 295-298

Original Article

Evaluation of Calypte AWARE HIV-1/2 OMT antibody test as a screening test in an Indian setting

NA Ingole, PR Mehta, RN Bande, SM Paranjpe, SW Wanjare

Department of Microbiology, Seth GSMC & KEMH, Parel, Mumbai - 400 012, India
Correspondence Address: N A Ingole, Department of Microbiology, Seth GSMC & KEMH, Parel, Mumbai - 400 012, India
nayanaingole@gmail.com

Date of Submission: 21-May-2010
Date of Acceptance: 05-Aug-2010

Code Number: mb10093

PMID: 20966557
DOI: 10.4103/0255-0857.71809

Abstract

Purpose: Integrated counselling and testing centres (ICTC) provide counselling and blood testing facilities for HIV diagnosis. Oral fluid tests provide an alternative for people whodo not want blood to be drawn. Also, it avoids the risk of occupational exposure. The goal of this study was to evaluate the utility of Calypte AWARE HIV-1/2 OMT antibody test as a screening test in an Indian setting.
Materials and Methods: A cross-sectional study was carried out after ethics committee approval in 250 adult ICTC clients. Blood was collected and tested from these clients for HIV diagnosis as per routine policy and the results were considered as the gold standard. Also, after another written informed consent, oral fluid was collected from the clients and tested for the presence of HIV antibodies. Twenty five clients who had and 25 clients who had not completed their secondary school education (Group A and Group B, respectively) were also asked to perform and interpret the test on their own and their findings and experiences were noted.
Result: The sensitivity, specificity, PPV and NPV of the oral fluid antibody test were 100%, 98.51%, 94.11% and 100%, respectively. Seventy six percent of clients preferred oral fluid testing. Group B found it difficult to perform the test as compared to Group A and this difference was statistically significant (P ≤ 0.05).
Conclusion: Oral fluid testing can be used as a screening test for HIV diagnosis; however, confirmation of reactive results by blood-based tests is a must.

Keywords: HIV diagnosis, oral fluid, screening tests

Introduction

Government of India has set up integrated counselling and testing centres (ICTCs) across the country for HIV diagnosis. These centres provide counselling facilities, and blood is collected for HIV antibody tests only after the client gives written informed consent. These tests require collection of blood from the client, which is an invasive procedure. Also, the person is reluctant to access this service as he has to personally come for the test. Tests that detect IgG antibodies present in oral fluid provide an alternative for such people. Also, it avoids the risk of needle-stick exposure for healthcare providers. Unfortunately, the use of oral fluids has been problematic due to specimen instability and assay insensitivity. An Indian study has reported a 100% sensitivity and specificity for the commercially available serum-based ELISA method using saliva. ^[1] Also, the Food and Drug Administration (FDA) USA has cleared the OraQuick ADVANCE HIV-1/2 antibody test for use with oral fluid and plasma, which has 99.3% sensitivity and greater than 99.6% specificity. ^[2] Calypte Biomedical Corporation has developed Calypte AWARE HIV-1/2 OMT antibody test using oral fluid samples. This test has demonstrated high sensitivity and specificity. ^[3] There is a school of thought that counselling, written informed consent and confidentiality should be done away with regards to HIV/AIDS, and HIV antibody testing should be treated as any other investigation. Home-based, non-invasive HIV testing would be a necessity in such a situation.

Hence the current study was carried out to evaluate the utility of Calypte AWARE HIV-1/2 OMT antibody test in an Indian setting. Also, the feasibility of using this test as a screening test in the ICTC was evaluated. For clients who hesitate to come forward for HIV testing due to the stigma and discrimination attached to the disease, the utility of this test as a home-based test for the diagnosis of HIV was evaluated in a small group of clients.

Materials and Methods

A cross-sectional study was carried out in 250 adult clients availing the ICTC services at Microbiology Department of a tertiary care hospital. Institutional ethics committee approved this study. After pre-test counselling and a written informed consent, blood was collected from these clients as per routine protocol and was tested for HIV antibody as per WHO/NACO HIV testing strategy III ^[4] and its results were considered as the 'gold standard'. In the pre-test counselling session, information regarding age, gender and educational status was obtained from the clients.

All clients giving consent for HIV testing were considered for participation in the study. Of these, clients consenting for study participation were enrolled. Calypte AWARE HIV-1/2 OMT antibody test kit manufactured by Calypte Biomedical Corporation, 5 Centrepointe Drive, Suite 411, Lake Oswego, OR, USA was used. As per instructions given in kit insert, oral fluid was collected from the clients [Figure - 1] and tested for the presence of HIV antibodies. After sample collection, patient's experience during blood and oral fluid collection was recorded in a questionnaire administered in a face-to-face interview by trained healthcare workers.

Some clients were given the option of performing the test on their own. Of those who were willing, 25 clients who had at least completed their secondary school education (Group A) and 25 clients who had not completed their secondary school education (Group B) were asked to perform and interpret the test on their own with the help of the kit insert (English/translated version in Marathi) and their findings and experience were noted down.

Statistical analysis

Analysis was conducted using Stata software (version 9.0; Stata Corp, College Station, TX, USA). The sensitivity, specificity, positive predictive value and negative predictive value of the Calypte AWARE HIV-1/2 OMT antibody test were compared to that of the serum antibody test. The feasibility of the test was evaluated using the Chi-square test or Fisher's exact test as applicable.

Results

A total of 250 participants were recruited and tested for HIV. The mean age of the study participants was 33.0 years (range 18-60 years). One hundred and ninety (76%) were men and 108 (43.2%) had not completed their secondary school education.

The oral fluid test was reactive in 51 (20.4%) clients as compared to 48 (19.2%) clients by serum-based tests [Figure - 2]. One sample, which was negative by oral fluid test and indeterminate by III serum-based tests, was later reported negative by western blot [Table - 1]. The sensitivity, specificity, PPV and NPV of the oral fluid test as compared to the serum-based test was 100%, 98.51%, 94.11% and 100%, respectively.

Seventy six percent of clients preferred oral fluid testing, 20% preferred serum/blood-based testing and 4% had no preference. Educational status of the participant did not make any difference with regards to preference of the test. Approximately 15.6% of clients complained of discomfort while collecting blood sample against 4.4% of clients who complained of discomfort while collecting oral fluid and this difference was statistically significant (P = 0.000 ).

Clients who had completed their secondary school education were significantly more confident with regards to oral fluid result and were also willing to perform the test at home.

A total of 50 clients performed the test on their own of which 25 were educated beyond secondary school level. Group B found it difficult to interpret the instructions mentioned in the kit insert (even when it was translated in local language) such as collecting the sample, performing the test and interpreting the result as compared to group A and this difference was statistically significant (P ≤ 0.05).

Discussion

Rapid point-of-care HIV testing is a very important component of HIV control initiatives and programmes. Calypte AWARE HIV-1/2 OMT antibody test for oral fluid sample is based on the principle of immunochromatography. This is a self-contained test, which does not require any additional equipment or consumables including refrigeration for storage. In a resource-limited setting like India, where the laboratory infrastructure is poor or unavailable at many sites, oral fluid tests can make a significant contribution in the expansion of HIV testing facilities to the primary level.

Oral fluid-based OraQuick tests have reported a sensitivity of 99.3% (95% CI 98.4, 99.7) and specificity of 99.8% (95% CI 99.6, 99.9). ^[3],[5] A study from central India in 2007 also reported 100% sensitivity and specificity using the OraQuick ADVANCE^® HIV-1/2 test. ^[6] Our finding of 100% sensitivity is comparable to these studies.

High rates of false-positive results with the oral fluid-based OraQuick® ADVANCE HIV-1/2 test have also been reported. ^[7],[8] From March 2005 to May 2008, the New York City Department of Health and Mental Hygiene (NYC DOHMH) administered 166 058 oral fluid rapid tests, with 442 (0.27%) false-positive test results. ^[9] In the current study, Calypte AWARE HIV-1/2 OMT antibody test also yielded three false-positive results. Since the sensitivity of this test was 100%, it can be used as a screening test. However, the specificity of 98.51% implies that the reactive results need to be confirmed by a second and/or third test. Similar recommendations have also been given by the US Centres for Diseases Control and Prevention (CDC) and CDC continues to support the use of the rapid oral fluid HIV test. ^[9]

The oral fluid sample should be tested within one hour of collection or can be preserved up to 12 h at 2−8°C. Hence, inability to preserve oral fluid samples for external quality assessment (EQA) is a limitation. This is especially important considering the false-positive test results seen in three cases.

As per response to the questionnaire, 96% of our clients gave their willingness for confirming their HIV status using blood-based antibody test in case the oral fluid-based screening test turns out to be reactive. Hence, this test can play an important role in HIV prevention efforts, making HIV testing possible in many venues outside of clinical settings, and increasing the opportunities for persons to learn their HIV status.

Majority of our clients preferred oral fluid collection (76%) to blood collection. Preference for oral HIV tests in previous studies ranged from 33 to 87%. ^{[6],[10],[11]} This preference may be due to various factors such as less discomfort and pain, fear of drawing blood, ease and non-invasiveness of sample collection method and its innovative nature.

Oral fluid-based testing also opens the possibility of home-based HIV testing. When patients were asked to perform the test on their own, a significant difference was seen in the understanding, performance and interpretation of results by the clients educated till secondary school level or more as compared to those not so well educated. Educated individuals who are not healthcare professionals could also use the test. But, in a country like India, with its diverse cultural, social, economic and educational background, the availability of this test as a home-based test may create a lot of problems.

This test comes in a self-contained packet inclusive of collection devices. The results of this test hence can be available within 15−20 minutes from time of collection of sample; whereas it takes about 1−2 h using the serum-based tests. Also, for serum-based test, extra cost, time and effort are required for collection and separation of serum samples. Hence, this test can find an application for emergency HIV testing of unregistered pregnant women directly coming for delivery similar to the whole-blood HIV antibody testing currently being used. Current WHO guidelines recommend provider-initiated HIV testing and counselling in place of client-initiated HIV testing and counselling - also known as voluntary counselling and testing (VCT) as the uptake of client-initiated HIV testing and counselling has been limited by low coverage of services, fear of stigma and discrimination, and the perception by many people - even in high prevalence areas - that they are not at risk. ^[12] In this scenario also oral fluid testing can play an important role as a bedside screening test.

For HIV sentinel surveillance since 2008 in high-risk groups like MSM, IDU, transgender, etc., where it is difficult to get the client to come to a healthcare facility for testing, NACO has recommended dried blood spot (DBS) testing. ^[13] Oral fluid testing can also find an application in this setting.

In prospective studies of healthcare workers, the average risk for HIV transmission after a percutaneous exposure to HIV-infected blood has been estimated to be approximately 0.3% (95% confidence interval [CI] = 0.2%−0.5%) and after a mucous membrane exposure, approximately 0.09% (CI = 0.006%−0.5%). ^[14] Possible transmission of HIV in two healthcare workers through needle-stick injuries has also been reported from India. ^[15] With the rapid spread of HIV epidemic in the Indian subcontinent, ignorance about universal safety precautions and post-exposure prophylaxis and the paucity in the availability of personal protective equipments (PPEs), oral fluid testing for HIV infection is an attractive alternative.

Conclusion

Calypte AWARE HIV-1/2 OMT test was rapid, easy, feasible, convenient and preferred over blood-based assays by majority of the clients. It had 100% sensitivity and hence can be used as a screening test especially for unregistered pregnant women directly coming for delivery. It has a specificity of 98.51%. Hence, confirmation of reactive results by blood-based tests is a must. Targeted oral fluid-based HIV testing in outreach settings can be used to expand the existing integrated counselling and testing programme.

References

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