At the recent Conference on Retroviruses and Opportunistic Infections (CROI 2026) in Denver, US, the use of an app for men with HIV who also use illicit stimulants led to 58% lower odds of having a detectable viral load after six months, when compared to a control group who did not use the app in a fully remote randomised controlled trial.
These results were presented by Professor Adam Carrico of Florida International University, a principal investigator on the Supporting Treatment Adherence for Resilience and Thriving (START) study. Fellow principal investigator Professor Sabina Hirshfield from SUNY Downstate Health Sciences University, New York City, gave aidsmap.com additional details on the intervention.
“Overall, we find that the START mHealth application achieved clinically meaningful – albeit short term – reductions in viral load,” Carrico said. “There is a need for comprehensive approaches, specifically those that integrate substance use treatment options, like remote contingency management.”
Limited options for men who use stimulants
Injection drug use, including of methamphetamine (crystal meth), remains a prominent driver of the HIV epidemic in the US and beyond. Gay and bisexual men often pair meth use with sex in what is known as chemsex. For men who have HIV, ongoing illicit stimulant use may affect antiretroviral therapy (ART) adherence, leading to a detectable viral load.
Carrico explained that, unlike for opioid use disorder, there are currently no US Food and Drug Administration-approved medications for stimulant use disorder. First-line treatments are therefore resource-intensive behavioural interventions. Durable reductions in meth use have been achieved with approaches such as cognitive behavioural therapies and contingency management, the latter providing financial incentives for documented instances of stimulant abstinence. However, these approaches can be costly, are time-consuming and may not always be accessible to men who use substances.
Prior research has demonstrated that apps may be an effective harm reduction tool. For instance, the Getting Off app worked to reduce meth injection and condomless anal sex. However, follow-up was only a month, and biomarker confirmation (such as urine samples) were lacking in this study.
“The goal of [the START] trial is to address the gap,” Carrico said. “To identify scalable mHealth interventions that reach the broader population of people with HIV, specifically those that experience the greatest difficulties with achieving and maintaining [an] undetectable viral load.”
The study
Overall, 286 men with HIV from across the US participated. Nearly half of the sample were ethnic and racial minorities (48%), with a median age of 42. All the men had screened positive for a stimulant use disorder, with most having meth use disorder (92%). Most men were not in substance use treatment (84%). Reports of challenges adhering to ART were common, with nearly half the sample having a detectable viral load (46%) at baseline, measured as a viral load above 300 copies.
“It was important for START to enrol men from groups often under-represented in biomedical HIV research, including men who use substances, because barriers can make study engagement harder,” Hirshfield explained. “To reduce those barriers, we expanded staff coverage across time zones and offered flexible virtual enrolment as well as text- and phone-based support with study tasks. About three-quarters of participants returned biospecimens at 12 months, demonstrating the feasibility of this remote approach and sustained engagement.”
A key feature of the START study is that participants were required to mail in dried blood spot biospecimens. Thus, viral load was not self-reported; it was objectively measured, at baseline and during the study.
In terms of the app’s content, it draws on Positive Psychological Interventions (PPIs), such as expressing gratitude, identifying strengths and mindfulness-based meditation. Thus, self-monitoring is a central aspect of engaging with the app. PPIs target withdrawal symptoms and negative reinforcement cycles from continued substance use and provide coping skills to deal with these challenging aspects.
“START has daily check-ins to track HIV medication and mood, plus modules with videos to guide practice exercises to build skills like gratitude, mindfulness, coping, and acts of kindness to support mental health and well-being,” Hirshfield said. “Strengthening these skills is theorised to reduce stress, improve mood, and maintain medication routines, leading to reduced viral rebound.”
Short-term viral load suppression
Based on dried blood spot analysis, men randomly allocated to have access to the app had 58% lower odds of having a detectable viral load at six months, when compared to men in the control arm (Adjusted Odds Ratio 0.42, 95% Confidence Interval 0.19-0.93). There was an approximately twofold greater virological rebound among the control group at the six-month mark (25% vs 48%).
The Number Needed to Treat was 5, indicating that on average, five people would need to receive the intervention for one additional person to achieve virological suppression. Carrico explained that this indicates that there’s “some evidence that if this was brought to scale, we would have a population health impact.”
Despite the app’s short-term success, there was no durable effect on viral load at one year. Additionally, there was no effect on meth severity use over a year.
However, as Hirshfield explained: “the START app was not developed to address substance use treatment, and most START participants were not in treatment at baseline. START did improve HIV viral suppression at 6 months by reducing viral rebound, but a lasting benefit may require pairing START with remote contingency management or other promising treatments.”
Carrico echoed this, when asked about considerations for future use. Ideally, the app would be integrated with telehealth psychotherapy, such as motivational interviewing and more substance use focused interventions, to provide longer-term benefits, both in terms of viral suppression and reduced stimulant use.
References
Carrico, A. The START mHealth Application Reduces Risk of Virologic Rebound in Men with HIV Who Use Stimulants. Conference on Retroviruses and Opportunistic Infections, Denver, abstract 184, 2026.
