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Aims: To describe the use of large-scale respondent driven sampling (RDS) surveys to demonstrate the "end of an HIV epidemic" (HIV incidence < 0.5/100 person-years) among persons who inject drugs (PWID) in a middle-income country. Large sample sizes are needed to convincingly demonstrate very low incidence rates. Methods: 4 large surveys (Ns approximately 1500 each) were conducted among PWID in Hai Phong, Vietnam in 2016–2019. Respondent driven sampling (RDS) with a modification to add snowball sampling was used for recruiting participants. HIV incidence was measured through recency testing, repeat participants across multiple surveys and in a cohort study of PWID recruited from the surveys. RDS analytics (time to equilibria and homophilies for major variables) were used to assess similarities/differences in RDS only versus RDS plus snowball recruiting. Characteristics were compared among respondents recruited through standard RDS recruitment versus through snowball sampling. An overall assessment of the robustness of RDS to modification was made when adding a snowball sampling recruitment. Results: RDS recruiting was very efficient in the first 5 weeks of each survey with approximately 180 respondents recruited per week. Recruiting then slowed considerably, and snowball sampling (permitting an individual respondent to recruit large numbers of new respondents) was added to the existing RDS recruiting. This led to recruiting within 13–14 weeks of 1383, 1451, 1444 and 1268 respondents, close to the target of 1500 respondents/survey. Comparisons of participants recruited through standard RDS method and respondents recruited through snowball methods showed very few significant differences. RDS analytics (quickly reaching equilibria, low homophilies) were favorable for both RDS recruited and total numbers of participants in each survey. DRug use and Infections in ViEtnam (DRIVE) methods have now been officially adopted in other provinces. Conclusions: RDS appears to be quite robust with respect to adding a modest number of participants recruited through snowball sampling. Large sample sizes can provide compelling evidence for "ending an HIV epidemic" to policy makers in a PWID population in a middle income country setting. [ABSTRACT FROM AUTHOR]

Background: Rifampicin and protease inhibitors are difficult to use concomitantly in patients with HIV-associated tuberculosis because of drug-drug interactions. Rifabutin has been proposed as an alternative rifamycin, but there is concern that the current recommended dose is suboptimal. The principal aim of this study was to compare bioavailability of two doses of rifabutin (150 mg three times per week and 150 mg daily) in patients with HIV-associated tuberculosis who initiated lopinavir/ritonavir-based antiretroviral therapy in Vietnam. Concentrations of lopinavir/ritonavir were also measured. Methods: This was a randomized, open-label, multi-dose, two-arm, cross-over trial, conducted in Vietnamese adults with HIV-associated tuberculosis in Ho Chi Minh City (Clinical trial registry number NCT00651066). Rifabutin pharmacokinetics were evaluated before and after the introduction of lopinavir/ritonavir -based antiretroviral therapy using patient randomization lists. Serial rifabutin and 25-O-desacetyl rifabutin concentrations were measured during a dose interval after 2 weeks of rifabutin 300 mg daily, after 3 weeks of rifabutin 150 mg daily with lopinavir/ritonavir and after 3 weeks of rifabutin 150 mg three times per week with lopinavir/ritonavir. Results: Sixteen and seventeen patients were respectively randomized to the two arms, and pharmacokinetic analysis carried out in 12 and 13 respectively. Rifabutin 150 mg daily with lopinavir/ritonavir was associated with a 32% mean increase in rifabutin average steady state concentration compared with rifabutin 300 mg alone. In contrast, the rifabutin average steady state concentration decreased by 44% when rifabutin was given at 150 mg three times per week with lopinavir/ritonavir. With both dosing regimens, 2 – 5 fold increases of the 25-O-desacetyl- rifabutin metabolite were observed when rifabutin was given with lopinavir/ritonavir compared with rifabutin alone. The different doses of rifabutin had no significant effect on lopinavir/ritonavir plasma concentrations. Conclusions: Based on these findings, rifabutin 150 mg daily may be preferred when co-administered with lopinavir/ritonavir in patients with HIV-associated tuberculosis. Trial Registration: ClinicalTrials.gov NCT00651066 [ABSTRACT FROM AUTHOR]

Background: Cryptococcal infection is a frequent cause of mortality in Cambodian HIV-infected patients with CD4+ count ≤100 cells/μl. This study assessed the cost-effectiveness of three strategies for cryptococcosis prevention in HIV-infected patients. Methods: A Markov decision tree was used to compare the following strategies at the time of HIV diagnosis: no intervention, one time systematic serum cryptococcal antigen (CRAG) screening and treatment of positive patients, and systematic primary prophylaxis with fluconazole. The trajectory of a hypothetical cohort of HIV-infected patients with CD4+ count ≤100 cells/μl initiating care was simulated over a 1-year period (cotrimoxazole initiation at enrollment; antiretroviral therapy within 3 months). Natural history and cost data (US$ 2009) were from Cambodia. Efficacy data were from international literature. Results: In a population in which 81% of patients had a CD4+ count ≤50 cells/ μl and 19% a CD4+ count between 51-100 cells/ml, the proportion alive 1 year after enrolment was 61% (cost $ 472) with no intervention, 70% (cost $ 483) with screening, and 72% (cost $ 492) with prophylaxis. After one year of follow-up, the cost-effectiveness of screening vs. no intervention was US$ 180/life year gained (LYG). The cost-effectiveness of prophylaxis vs. screening was $ 511/LYG. The costeffectiveness of prophylaxis vs. screening was estimated at $1538/LYG if the proportion of patients with CD4+ count ≤50 cells/μl decreased by 75%. Conclusion: In a high endemic area of cryptococcosis and HIV infection, serum CRAG screening and prophylaxis are two cost effective strategies to prevent AIDS associated cryptococcosis in patients with CD4+ count ≤100 cells/μl, at a short-term horizon, screening being more cost-effective but less effective than prophylaxis. Systematic primary prophylaxis may be preferred in patients with CD4+ below 50 cells/μl while systematic serum CRAG screening for early targeted treatment may be preferred in patients with CD4+ between 51-100 cells/μl. [ABSTRACT FROM AUTHOR]