Arlene Chua

Accuracy and User-Acceptability of HIV Self-Testing Using an Oral Fluid-Based HIV Rapid Test

Background The United States FDA approved an over-the-counter HIV self-test, to facilitate increased HIV testing and earlier linkage to care. We assessed the accuracy of self-testing by untrained participants compared to healthcare worker (HCW) testing, participants’ ability to interpret sample results and user-acceptability of self-tests in Singapore. Methodology/Principal Findings A cross-sectional study, involving 200 known HIV-positive patients and 794 unknown HIV status at-risk participants was conducted. Participants (all without prior self-test experience) performed self-testing guided solely by visual instructions, followed by HCW testing, both using the OraQuick ADVANCE Rapid HIV 1/2 Antibody Test, with both results interpreted by the HCW. To assess ability to interpret results, participants were provided 3 sample results (positive, negative, and invalid) to interpret. Of 192 participants who tested positive on HCW testing, self-testing was positive in 186 (96.9%), negative in 5 (2.6%), and invalid in 1 (0.5%). Of 794 participants who tested negative on HCW testing, self-testing was negative in 791 (99.6%), positive in 1 (0.1%), and invalid in 2 (0.3%). Excluding invalid tests, self-testing had sensitivity of 97.4% (95% CI 95.1% to 99.7%) and specificity of 99.9% (95% CI: 99.6% to 100%). When interpreting results, 96%, 93.1% and 95.2% correctly read the positive, negative and invalid respectively. There were no significant demographic predictors for false negative self-testing or wrongly interpreting positive or invalid sample results as negative. Eighty-seven percent would purchase the kit over-the-counter; 89% preferred to take HIV tests in private. 72.5% and 74.9% felt the need for pre- and post-test counseling respectively. Only 28% would pay at least USD15 for the test. Conclusions/Significance Self-testing was associated with high specificity, and a small but significant number of false negatives. Incorrectly identifying model results as invalid was a major reason for incorrect result interpretation. Survey responses were supportive of making self-testing available.

Epidemiology of travel-associated pandemic (H1N1) 2009 infection in 116 patients, Singapore.

During the containment phase, regions of exposure for imported infections changed rapidly.

High prevalence of CXCR4 usage among treatment-naive CRF01_AE and CRF51_01B-infected HIV-1 subjects in Singapore

BackgroundRecent studies suggest HIV-1 inter-subtype differences in co-receptor usage. We examined the correlation between HIV-1 subtype and co-receptor usage among treatment-naïve HIV-1 subjects in Singapore. Additionally, we investigated whether the subtype co-receptor association was influenced by stage of infection.MethodsV3 sequences of HIV-1 envelope protein gp120 were obtained from 110 HIV treatment-naïve patients and genotypic co-receptor tropism determination was performed using Geno2pheno. Two false-positive rate (FPR) cut-offs, 10% and 5.75% were selected for tropism testing.ResultsSubtype assignment of viral strains from 110 HIV-infected individuals based on partial sequencing of HIV-1 pol, gp120 and gp41 were as follows: 27 subtype B, 64 CRF01_AE, 10 CRF51_01B, and 9 other subtypes. At FPR=10%, 10 (100%) CRF51_01B-infected subjects and 26 (40.6%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 7 (25.9%) subtype B subjects and 1 (11.1%) CRF33_01B-infected subject (P < 0.001). At FPR=5.75%, 10 (100%) CRF51_01B-infected subjects and 20 (31.3%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 4 (14.8%) subtype B and 1 (11.1%) CRF33_01B-infected subjects (P < 0.001). Among those with evidence of seroconversion within 2 years prior to study enrolment, 100% of CRF51_01B-infected subjects had CXCR4-using virus, independent of Geno2pheno FPR.ConclusionCRF51_01B and CRF01_AE-infected individuals have higher prevalence of CXCR4-usage compared to subtype B infected individuals. Further studies examining these differences could help optimise the use of CCR5-antagonist in populations with these subtypes, and increase our understanding of HIV-1 biology.

Opt-out of Voluntary HIV Testing: A Singapore Hospital's Experience

Introduction Since 2008, the Singapore Ministry of Health (MOH) has expanded HIV testing by increasing anonymous HIV test sites, as well as issuing a directive to hospitals to offer routine voluntary opt out inpatient HIV testing. We reviewed this program implemented at the end of 2008 at Tan Tock Seng Hospital (TTSH), the second largest acute care general hospital in Singapore. Methods and Findings From January 2009 to December 2010, all inpatients aged greater or equal than 21 years were screened for HIV unless they declined or were not eligible for screening. We reviewed the implementation of the Opt Out testing policy. There were a total of 93,211 admissions; 41,543 patients were included based on HIV screening program eligibility criteria. Among those included, 79% (n = 32,675) opted out of HIV screening. The overall acceptance rate was 21%. Majority of eligible patients who were tested (63%) were men. The mean age of tested patients was 52 years. The opt out rate was significantly higher among females (OR: 1.5, 95%CI: 1.4–1.6), aged >60 years (OR: 2.3, 95%CI: 2.2–2.4) and Chinese ethnicity (OR: 1.7, 95%CI:1.6–1.8). The false positive rate of the HIV screening test is 0.56%. The proportion of patients with HIV infection among those who underwent HIV screening is 0.18%. All16 confirmed HIV patients were linked to care. Conclusion The default opt-in rate of inpatient HIV testing was low at Tan Tock Seng Hospital, Singapore. Efforts to address individual HIV risk perception and campaigns against HIV stigma are needed to encourage more individuals to be tested for HIV.