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Modeling the rate of HIV testing from repeated binary data amidst potential never-testers.

ABSTRACT: Many longitudinal studies with a binary outcome measure involve a fraction of subjects with a homogeneous response profile. In our motivating data set, a study on the rate of human immunodeficiency virus (HIV) self-testing in a population of men who have sex with men (MSM), a substantial proportion of the subjects did not self-test during the follow-up study. The observed data in this context consist of a binary sequence for each subject indicating whether or not that subject experienced any events between consecutive observation time points, so subjects who never self-tested were observed to have a response vector consisting entirely of zeros. Conventional longitudinal analysis is not equipped to handle questions regarding the rate of events (as opposed to the odds, as in the classical logistic regression model). With the exception of discrete mixture models, such methods are also not equipped to handle settings in which there may exist a group of subjects for whom no events will ever occur, i.e. a so-called "never-responder" group. In this article, we model the observed data assuming that events occur according to some unobserved continuous-time stochastic process. In particular, we consider the underlying subject-specific processes to be Poisson conditional on some unobserved frailty, leading to a natural focus on modeling event rates. Specifically, we propose to use the power variance function (PVF) family of frailty distributions, which contains both the gamma and inverse Gaussian distributions as special cases and allows for the existence of a class of subjects having zero frailty. We generalize a computational algorithm developed for a log-gamma random intercept model (Conaway, 1990. A random effects model for binary data. Biometrics46, 317-328) to compute the exact marginal likelihood, which is then maximized to obtain estimates of model parameters. We conduct simulation studies, exploring the performance of the proposed method in comparison with competitors. Applying the PVF as well as a Gaussian random intercept model and a corresponding discrete mixture model to our motivating data set, we conclude that the group assigned to receive follow-up messages via SMS was self-testing at a significantly lower rate than the control group, but that there is no evidence to support the existence of a group of never-testers.

SUBMITTER: Rice JD

PROVIDER: S-EPMC6513024 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Modeling the rate of HIV testing from repeated binary data amidst potential never-testers.

Rice John D JD Johnson Brent A BA Strawderman Robert L RL

Biostatistics (Oxford, England) 20190401 2

Many longitudinal studies with a binary outcome measure involve a fraction of subjects with a homogeneous response profile. In our motivating data set, a study on the rate of human immunodeficiency virus (HIV) self-testing in a population of men who have sex with men (MSM), a substantial proportion of the subjects did not self-test during the follow-up study. The observed data in this context consist of a binary sequence for each subject indicating whether or not that subject experienced any eve ...[more]

PMID: 29315363

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Project description:BackgroundCoverage of HIV testing remains sub-optimal in West Africa. Between 2019 and 2022, the ATLAS program distributed ~400 000 oral HIV self-tests (HIVST) in Côte d'Ivoire, Mali, and Senegal, prioritising female sex workers (FSW) and men having sex with men (MSM), and relying on secondary redistribution of HIVST to partners, peers and clients to reach individuals not tested through conventional testing. This study assesses the proportion of first-time testers among HIVST users and the associated factors.MethodsA phone-based survey was implemented among HIVST users recruited using dedicated leaflets inviting them to anonymously call a free phone number. We collected socio-demographics, sexual behaviours, HIV testing history, HIVST use, and satisfaction with HIVST. We reported the proportion of first-time testers and computed associated factors using logistic regression.ResultsBetween March and June 2021, 2 615 participants were recruited for 50 940 distributed HIVST (participation rate: 5.1%). Among participants, 30% received their HIVST kit through secondary distribution (from a friend, sexual partner, family member, or colleague). The proportion who had never tested for HIV before HIVST (first-time testers) was 41%. The main factors associated with being a first-time tester were sex, age group, education level, condom use, and secondary distribution. A higher proportion was observed among those aged 24 years or less (55% vs 32% for 25-34, aOR: 0.37 [95%CI: 0.30-0.44], and 26% for 35 years or more, aOR: 0.28 [0.21-0.37]); those less educated (48% for none/primary education vs 45% for secondary education, aOR: 0.60 [0.47-0.77], and 29% for higher education, aOR: 0.33 [0.25-0.44]). A lower proportion was observed among women (37% vs 43%, aOR: 0.49 [0.40-0.60]); those reporting always using a condom over the last year (36% vs 51% for those reporting never using them, aOR: 2.02 [1.59-2.56]); and those who received their HISVST kit through primary distribution (39% vs 46% for secondary distribution, aOR: 1.32 [1.08-1.60]).ConclusionATLAS HIVST strategy, including secondary distribution, successfully reached a significant proportion of first-time testers. HIVST has the potential to reach underserved populations and contribute to the expansion of HIV testing services in West Africa.

Project description:IntroductionHIV diagnoses among gay and bisexual men have increased over the past decade in Australia. HIV point-of-care testing (POCT) was introduced in Australia in 2011 as a strategy to increase HIV testing by making the testing process more convenient. We surveyed gay and bisexual men undergoing POCT to assess barriers to HIV testing and characteristics associated with not having previously tested for HIV (never testing).MethodsDuring 2011 and 2012, gay and bisexual men who were undergoing POCT at four Sydney sexual health clinics self-completed questionnaires assessing testing history and psychological and structural barriers to HIV testing. Bivariate and multivariate logistic regression was used to assess associations between patient characteristics and never testing.ResultsOf 1093 participants, 981 (89.9%) reported ever testing for HIV and 110 (10.1%) never testing. At least one barrier to testing was reported by 1046 men (95.7%), with only 47 men (4.3%) not reporting any barrier to testing. The most commonly reported barriers to testing were annoyance at having to return for results (30.2%), not having done anything risky (29.6%), stress in waiting for results (28.4%), being afraid of testing positive (27.5%) and having tested recently (23.2%). Never testing was independently associated with being non-gay-identified (adjusted odds ratio [AOR]: 1.9; 95% confidence interval [CI]: 1.1-3.2), being aged less than 25 years (AOR: 2.4; 95% CI: 1.6-3.8), living in a suburb with few gay couples (AOR: 1.9; 95% CI: 1.2-3.0), being afraid of testing HIV-positive (AOR: 1.6; 95% CI: 1.0-2.4), not knowing where to test (AOR: 3.8; 95% CI: 1.3-11.2) and reporting one or no sexual partners in the last six months (AOR: 2.7; 95% CI: 1.2-6.2).ConclusionsBarriers to HIV testing were commonly reported among the clinic-based gay and bisexual men in this study. Our findings suggest further health promotion and prevention strategies are needed to address the knowledge, attitudes and behavioural factors associated with never testing.

Project description:BackgroundCouples HIV testing and counseling (CHTC) is now a standard of care prevention strategy recommended by the Centers for Disease Control and Prevention for sexual minority men (SMM) in relationships. Despite standard recommendations that couples complete CHTC every 6-12 months, no study has empirically evaluated the effects associated with CHTC retesting.ObjectiveThis study aims to understand the benefits associated with continued dyadic engagement in the HIV prevention continuum through routine CHTC retesting, which is of particular importance for emerging-adult SMM in relationships who use drugs.MethodsEligible couples for this CHTC retesting trial must already be enrolled in the 4Us trial, where they completed a CHTC session after their baseline survey. The purpose of the original 4Us trial was to test the efficacy of 2 intervention components for CHTC: a communication skills training video and a substance use module. Couples were eligible for the original 4Us trial if they identified as cisgender male, were in a relationship for 3 months or longer, were aged 17 years or older, and communicated in English. At least 1 partner had to be aged 17-29 years, report HIV negative or unknown serostatus, report use of at least 1 drug (cannabis, cocaine or crack, crystal methamphetamine, ketamine, gamma-hydroxybuterate [GHB], psychedelics, ecstasy, prescription medication misuse, opiates, and nitrates) use, and engage in condomless anal sex (CAS) acts with a casual partner or have a main partner who is nonmonogamous or serodiscordant. Those who complete the 4Us 12-month follow-up and remain in a relationship with the partner they participated in 4Us with are offered the opportunity to participate in this CHTC retesting trial. Those consenting are randomized to either CHTC retesting or individual HIV testing. Follow-up assessments are conducted 3 and 6 months after randomization to evaluate the effects of repeat CHTC on 2 primary outcomes: (1) CAS with a casual partner in the absence of preexposure prophylaxis (PrEP), and (2) CAS with a serodiscordant main partner who is not virally suppressed or concurrent CAS between main and casual partners in the absence of PrEP.ResultsThe CHTC retesting trial launched in January 2023, and enrollment is ongoing. As of February 2024, the study had enrolled 106 eligible participants (n=53 couples).ConclusionsFindings from this CHTC retesting study will contribute to knowledge about the benefits associated with regular (repeated) CHTC testing versus routine individual HIV testing for SMM in relationships. The results of this trial will inform CHTC retesting guidance.Trial registrationClinicalTrials.gov NCT05833074; htps://www.clinicaltrials.gov/study/NCT05833074.International registered report identifier (irrid)DERR1-10.2196/53023.

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Modeling the rate of HIV testing from repeated binary data amidst potential never-testers.

Publications

Modeling the rate of HIV testing from repeated binary data amidst potential never-testers.

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