HIV viral non-suppression and drug resistance among persons who inject drugs on dolutegravir antiretroviral therapy in Kenya

In a two-year Kenyan study of people who inject drugs on dolutegravir-based antiretroviral therapy, approximately one-third experienced viral non-suppression, with living in improvised shelters identified as a significant risk factor, while dolutegravir resistance mutations remained rare despite frequent NNRTI resistance.

The Gist

The Big Picture: A Race Against the Virus in Kenya

Imagine the human body as a busy city, and the HIV virus as a group of unruly vandals trying to take over the power grid. The goal of HIV treatment is to keep the lights on and the vandals locked out.

For a long time, the "security guards" (medications) used in Kenya were good, but they had a weakness: the vandals could learn to pick the locks over time. So, Kenya switched to a newer, stronger security system called TLD (a combination of three drugs, with the star player being Dolutegravir or DTG). This new system is like a high-tech, unbreakable smart-lock.

This study is like a two-year security camera report. The researchers followed 250 people who inject drugs (a group often overlooked and facing huge challenges like homelessness and stigma) in Kenya. They wanted to see two things:

1. Did the new smart-lock keep the vandals out (viral suppression)?
2. Did the vandals learn to pick the new lock (drug resistance)?

The Cast of Characters

The people in this study face a storm of difficulties. Many are homeless, living in makeshift shelters or on the streets. Many struggle with heroin addiction. It's like trying to keep a house clean while a hurricane is blowing through the windows. Despite these challenges, the researchers wanted to see if the new medicine could still work.

The Results: Mostly Good News, But a Warning Sign

1. The Lock Held (Mostly)
For about two-thirds of the participants, the new medicine worked perfectly. The virus was completely suppressed, meaning the "vandals" were locked out, and the city was safe. This is great news because it means the new treatment is effective even for this difficult-to-reach group.

2. The "Intermittent" Problem
However, about one-third of the people had a bumpy ride. Their virus levels would go up and down.

• The Analogy: Imagine a car with a flat tire. Sometimes the driver stops to fix it (takes their meds), and the car runs smooth. Other times, they forget, the tire goes flat again, and the car sputters.
• The Cause: The study found that the biggest reason for these "flat tires" wasn't the medicine itself, but where the people lived. Those living in makeshift shelters or on the streets were 4 times more likely to have their virus flare up. It's hard to take daily medicine when you don't have a safe, stable place to sleep or store your pills.

3. The "Vandal" Didn't Learn the New Lock
This is the most exciting part. Even though some people's virus levels went up, the virus did not learn to break the new smart-lock (DTG).

• The researchers found that the virus was still very good at breaking the old locks (the older drugs), but it was completely helpless against the new DTG lock.
• Only a tiny, tiny fraction (1%) showed a sign of trying to learn the new lock, and even then, it was a very weak attempt.
• The Metaphor: It's like the vandals tried to pick the new smart-lock, but they only managed to scratch the paint. The lock still works perfectly.

Why This Matters

The "Housing" Lesson:
The study teaches us that medicine alone isn't a magic wand. If you give someone a perfect lock but they are living in a storm, the lock might get damaged. The study suggests that to keep HIV under control in this group, we need to fix the housing and stability issues first. You can't expect someone to take their pills perfectly if they are worried about where they will sleep tonight.

The "Safety Net" Lesson:
The researchers noticed that when they checked the patients frequently (every 6 months) and sent "peer educators" to help those who missed a dose, the patients often got back on track. This is like having a friendly neighbor who knocks on the door to remind you to take your vitamins. If we stop checking in, the virus might get a chance to grow back.

The Bottom Line

The new HIV medicine (DTG) is a superhero for people who inject drugs in Kenya. It is strong, effective, and the virus hasn't figured out how to beat it yet.

However, the superhero needs a sidekick: stable housing and consistent support. If we can help these individuals find a safe place to live and keep them connected to their doctors, we can keep the virus locked out for good, stop it from spreading, and save lives.

In short: The medicine works, but the patient needs a home to take it in.

Technical Summary

1. Problem Statement

People who inject drugs (PWID) living with HIV in sub-Saharan Africa face significant barriers to care, including homelessness, incarceration, stigma, and food insecurity, leading to higher rates of viral non-suppression compared to the general population. While the World Health Organization (WHO) and the Kenyan Ministry of Health have transitioned first-line antiretroviral therapy (ART) to the dolutegravir (DTG)-based regimen (Tenofovir + Lamivudine + DTG, or TLD) to improve efficacy and tolerability, there is a paucity of real-world data regarding:

• The longitudinal rates of viral non-suppression among PWID on DTG.
• The emergence of drug resistance mutations (specifically to DTG) in this high-risk, key population.
• Whether pre-existing resistance from previous regimens (Efavirenz-based) impacts outcomes on TLD.

2. Methodology

• Study Design: A prospective longitudinal cohort study conducted in Kenya (Nairobi and the coastal region) between May 2021 and September 2023.
• Participants: 250 PWID (aged ≥18) who had been on DTG-based regimens for at least 6 months prior to enrollment.
  • Demographics: 70% male, median age 39, 79.6% reported heroin use, and 50% were on methadone maintenance therapy.
• Data Collection:
  • Participants underwent five visits over 24 months (baseline, 6, 12, 18, and 24 months).
  • Virologic Monitoring: Plasma HIV RNA viral load (VL) was measured at every visit using the Abbott RealTime HIV-1 assay. Viremia was defined as VL >200 copies/mL.
  • Genotyping: Viremic specimens were genotyped for drug resistance using a lab-developed PacBio sequencing assay (targeting the pol gene: protease, reverse transcriptase, and integrase). If PacBio failed, Sanger sequencing was used.
  • Resistance Analysis: Data were analyzed using the Stanford HIVdb program. "Major" resistance was defined by specific mutation scores (e.g., >10 for DTG).
• Statistical Analysis:
  • Univariable and multivariable Cox proportional hazards models were used to identify risk factors for time-to-viremia.
  • Fisher's exact test assessed associations between pre-treatment resistance and subsequent viral non-suppression.

3. Key Contributions

• Longitudinal Focus: Unlike cross-sectional studies, this research tracks viral suppression and resistance emergence over a full 2-year period in a key population.
• Advanced Sequencing: The use of PacBio long-read sequencing allowed for the detection of minority variants (low-frequency resistance mutations) that standard Sanger sequencing might miss.
• Contextual Insight: The study specifically addresses the transition from NNRTI-based regimens (Efavirenz) to INSTI-based regimens (DTG) in a resource-limited setting with a high burden of injection drug use.

4. Key Results

• Viral Suppression Rates:
  • Overall: 66.0% of participants remained consistently suppressed throughout the study.
  • Viremia: 33.6% experienced viremia at least once.
    • 3.2% were always viremic.
    • 30.4% were intermittently viremic (suppressed at some visits, viremic at others).
  • Follow-up: 77.6% completed all 5 visits; 16.4% were lost to follow-up, and 6.0% died.
• Risk Factors for Viremia:
  • Housing Instability: Living in an improvised shelter or outdoors was significantly associated with a higher risk of viremia (Unadjusted HR = 4.35; 95% CI: 1.52–12.53).
  • Methadone: Being on methadone was not a significant protective factor against viremia in this cohort, likely because many methadone users continued heroin use and all participants received close monitoring.
  • Pre-existing Resistance: Having pre-treatment resistance mutations (NNRTI or NRTI) was not associated with viral non-suppression on the new TLD regimen.
• Drug Resistance Patterns:
  • NNRTI Resistance: Highly prevalent (37–41% of viremic specimens), reflecting historical use of Efavirenz.
  • NRTI Resistance: Low prevalence for Tenofovir (4.3%) and Lamivudine (7.5%).
  • DTG Resistance:
    • Major Resistance: Extremely rare. Only 1% of genotyped specimens showed a major DTG resistance mutation (minority variant S153F detected at 1% frequency).
    • Accessory Mutations: Common (41% of specimens), including T97A, E138K, and L74M. These do not independently reduce DTG susceptibility but may act as precursors to resistance.
  • Viral Load: The median viral load when viremic was high (16,654 copies/mL), suggesting periods of complete non-adherence rather than partial adherence (which typically selects for resistance).

5. Significance and Implications

• Clinical Outcomes: The DTG-based TLD regimen is highly effective for PWID in Kenya, with the majority achieving and maintaining viral suppression. The low rate of major DTG resistance suggests that the regimen remains robust even in this high-risk population.
• Social Determinants: The study highlights that housing instability is the primary driver of treatment failure for PWID, rather than biological factors like pre-existing drug resistance. Interventions must address social determinants (e.g., shelter, food security) alongside medical care.
• Monitoring Strategy: The high rate of intermittent viremia (30.4%) suggests that annual viral load monitoring may be insufficient for PWID. More frequent (e.g., biannual) monitoring and rapid re-engagement strategies (peer tracing) are critical to prevent the development of resistance.
• Public Health: Despite high NNRTI resistance from previous regimens, the switch to TLD has not led to widespread DTG resistance. However, the presence of accessory mutations warrants continued surveillance to prevent the accumulation of mutations that could eventually compromise DTG efficacy.
• Policy Context: The findings underscore the fragility of care continuity for key populations, particularly with the potential withdrawal of PEPFAR support in 2025, emphasizing the need for sustainable, locally managed support systems.