Comparative effectiveness of immediate antiretroviral therapy versus CD4-based initiation in HIV-positive individuals in high-income countries: observational cohort study

Rapid antiretroviral therapy and treatment outcomes among people living with HIV: exploring the mediating roles of medication adherence

Introduction

The rapid initiation of antiretroviral therapy (ART) and its impact on treatment outcomes have been a subject of global public health interest. However, the precise mechanisms underlying the effects of rapid ART initiation remain unclear.

Methods

This retrospective cohort study examined data from 1846 HIV-infected individuals in Jiulongpo District, Chongqing, China, spanning from 2016 to 2022. Logistic regression models and serial mediation analysis were used to explore the influence of rapid ART initiation on treatment outcomes and the role of medication adherence as a mediating factor.

Results

The findings revealed a significant association between rapid ART initiation and reduced risk of viral failure (adjusted odds ratio [OR] = 0.320, 95% confidence interval [CI] = [0.161, 0.637]), as well as an increased likelihood of improved adherence (adjusted OR = 2.053, 95% CI = [1.226, 3.438]). Medication adherence was identified as a partial mediator in the relationship between rapid ART initiation and viral failure, explaining 10.5% of the total effect.

Discussion

In conclusion,rapid initiation of antiretroviral therapy was found to enhance treatment outcomes, emphasizing the importance of early adherence education. The study recommends early initiation of ART coupled with adherence education and psychological counseling for HIV-infected individuals.

Enhanced Cohort Methods for HIV Research and Epidemiology (ENCORE): Protocol for a Nationwide Hybrid Cohort for Transgender Women in the United States

BACKGROUND

In the United States, transgender women are disproportionately impacted by HIV and prioritized in the national strategy to end the epidemic. Individual, interpersonal, and structural vulnerabilities underlie HIV acquisition among transgender women and fuel syndemic conditions, yet no nationwide cohort monitors their HIV and other health outcomes.

OBJECTIVE

Our objective is to develop a nationwide cohort to estimate HIV incidence, identify risk factors, and investigate syndemic conditions co-occurring with HIV vulnerability or acquisition among US transgender women. The study is informed by the Syndemics Framework and the Social Ecological Model, positing that stigma-related conditions are synergistically driven by shared multilevel vulnerabilities.

METHODS

To address logistical and cost challenges while minimizing technology barriers and research distrust, we aim to establish a novel, hybrid community hub-supported digital cohort (N=3000). The digital cohort is the backbone of the study and is enhanced by hubs strategically located across the United States for increased engagement and in-person support. Study participants are English or Spanish speakers, are aged ≥18 years, identify as transgender women or along the transfeminine spectrum, reside in 1 of the 50 states or Puerto Rico, and do not have HIV (laboratory confirmed). Participants are followed for 24 months, with semiannual assessments. These include a questionnaire and laboratory-based HIV testing using self-collected specimens. Using residential zip codes, person-level data will be merged with contextual geolocated data, including population health measures and economic, housing, and other social and structural factors. Analyses will (1) evaluate the contribution of hub support to the digital cohort using descriptive statistics; (2) estimate and characterize syndemic patterns among transgender women using latent class analysis; (3) examine the role of contextual factors in driving syndemics and HIV prevention over time using multilevel regression models; (4) estimate HIV incidence in transgender women and examine the effect of syndemics and contextual factors on HIV incidence using Poisson regression models; and (5) develop dynamic, compartmental models of multilevel combination HIV prevention interventions among transgender women to simulate their impact on HIV incidence through 2030.

RESULTS

Enrollment launched on March 15, 2023, with data collection phases occurring in spring and fall. As of February 24, 2024, a total of 3084 individuals were screened, and 996 (32.3%) met the inclusion criteria and enrolled into the cohort: 2.3% (23/996) enrolled at a hub, and 53.6% (534/996) enrolled through a community hub-supported strategy. Recruitment through purely digital methods contributed 61.5% (1895/3084) of those screened and 42.7% (425/996) of those enrolled in the cohort.

CONCLUSIONS

Study findings will inform the development of evidence-based interventions to reduce HIV acquisition and syndemic conditions among US transgender women and advance efforts to end the US HIV epidemic. Methodological findings will also have critical implications for the design of future innovative approaches to HIV research.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/59846.

Target trial emulation for comparative effectiveness research with observational data: Promise and challenges for studying medications for opioid use disorder

Medications for opioid use disorder (MOUD) increase retention in care and decrease mortality during active treatment; however, information about the comparative effectiveness of different forms of MOUD is sparse. Observational comparative effectiveness studies are subject to many types of bias; a robust framework to minimize bias would improve the quality of comparative effectiveness evidence. This paper discusses the use of target trial emulation as a framework to conduct comparative effectiveness studies of MOUD with administrative data. Using examples from our planned research project comparing buprenorphine-naloxone and extended-release naltrexone with respect to the rates of MOUD discontinuation, we provide a primer on the challenges and approaches to employing target trial emulation in the study of MOUD.

Demographic and clinical factors correlated with clinical outcomes among people with HIV treated by antiretroviral therapy: a retrospective cohort study

BACKGROUND

As is known, CD4 cell count is a significant parameter predicting HIV progression, opportunistic infections and death in HIV-infected individuals, as well was an important indicator for initiating antiretroviral therapy (ART). In China's National Free Antiretroviral Treatment Program, people with HIV (PWH) on ART can receive a CD4 count test at least once every six months. Importantly, the baseline CD4 count (before ART initiation) is significantly correlated with ART and even prognosis, but the influence of the peak CD4 cell count on ART and/or clinical outcomes is still unknown.

METHODS

A retrospective study was conducted among 7965 PWH who received ART from October 2003 to September 2022 at Yunnan Infectious Disease Hospital. Clinical features and laboratory data were collected and analyzed by Chi-square test, univariate and multivariate Cox regression analysis. After elimination of confounding variables, multivariate Cox regression analysis was performed to identify survival-related factors.

RESULTS

Of a total of 7965 PWH in the ART treatment cohort who met the inclusion and exclusion criteria, 7939 were finally included in the subsequent analyses. First, it was found that the proportion of clinical variables, including sex, age distribution, interval from diagnosis to ART initiation, marital status, and others, was significantly different between the living and dead groups (P < 0.05). Impressively, significantly more PWH had the higher level of baseline, peak and recent CD4 cell counts in the living group compared to those in the dead group. Due to multicollinearity effect, after excluding confounders, the following factors were found to be significantly associated with mortality by multivariate Cox regression analysis: (1) male sex (hazard ratio (HR) = 1.268 [1.032, 1.559]; P = 0.024); (2) time from HIV confirmation to ART initiation ≥ 6 months (HR = 1.962 [1.631, 2.360]; P < 0.001); (3) peak CD4 cell count: Peak CD4 < 100cells/µL group (HR = 16.093 [12.041, 21.508]; P < 0.001), 100cells/µL ≤ x < 200cells/µL group (HR = 7.904 [6.148, 10.160]; P < 0.001), 200cells/µL ≤ x < 350cells/µL group (HR = 3.166 [2.519, 3.980]; P < 0.001), 350cells/µL ≤ x < 500cells/µL group (HR = 1.668 [1.291, 2.155]; P < 0.001).

CONCLUSION

Interestingly, patients in male, time from HIV confirmation to ART initiation ≥ 6 months, or peak CD4 count < 500 cells/µl had inferior clinical outcomes, in other word, a lower peak CD4 cell count significantly increased the risk of death, and peak CD4 cell was independent in predicting the overall survival of PWH. It is important to promote "early diagnosis and treatment of HIV" and regularly monitor CD4 levels in HIV/AIDS to evaluate the efficacy of ART and immune reconstitution, and optimize the ART regimen in time to further reduce the mortality of PWH.

Evaluating Model Specification When Using the Parametric G-Formula in the Presence of Censoring

The noniterative conditional expectation (NICE) parametric g-formula can be used to estimate the causal effect of sustained treatment strategies. In addition to identifiability conditions, the validity of the NICE parametric g-formula generally requires the correct specification of models for time-varying outcomes, treatments, and confounders at each follow-up time point. An informal approach for evaluating model specification is to compare the observed distributions of the outcome, treatments, and confounders with their parametric g-formula estimates under the "natural course." In the presence of loss to follow-up, however, the observed and natural-course risks can differ even if the identifiability conditions of the parametric g-formula hold and there is no model misspecification. Here, we describe 2 approaches for evaluating model specification when using the parametric g-formula in the presence of censoring: 1) comparing factual risks estimated by the g-formula with nonparametric Kaplan-Meier estimates and 2) comparing natural-course risks estimated by inverse probability weighting with those estimated by the g-formula. We also describe how to correctly compute natural-course estimates of time-varying covariate means when using a computationally efficient g-formula algorithm. We evaluate the proposed methods via simulation and implement them to estimate the effects of dietary interventions in 2 cohort studies.

Survival times of HIV/AIDS in different AIDS Diagnostic and Treatment Guidelines from 2006 to 2020 in Liuzhou, China

BACKGROUND

To compare the survival rates of four timing of treatment initiation for people living with HIV/AIDS provided in China in 2006, 2011, 2015, and 2018, and to investigate the factors impacting survival time.

METHODS

A people living with HIV/AIDS retrospective cohort study was in Liuzhou City from April 2006 to December 2020. The information was obtained from the National Comprehensive AIDS Prevention and Control Information System. Life tables and the Kaplan-Meier method were used to calculate participant survival rates and time. The univariate and multivariate Cox regression models were used to investigate the factors related to survival.

RESULTS

18,543 participants were included in this study. In four periods, the 1-year survival rates were 81%, 87%, 95%, and 95%. The 2-year survival rates were 76%, 85%, 93%, and 94%. The 3-year survival rates were 73%, 84%, 92%, and 94%. Results of multivariate Cox regression showed that sex, age of HIV diagnosis, ethnicity, household registration, occupation, marital status, the timing of treatment, education level, route of HIV transmission, whether receiving antiretroviral therapy (ART), and the count of CD4+T cells at baseline (count of CD4+T cells at HIV diagnosis) were factors that are significantly correlated with mortality caused by HIV infection.

CONCLUSIONS

With the Guidelines updated from 2006 to 2020, the 1-, 2-, and 3-year survival rates of people living with HIV/AIDS in four periods tended to increase. The timing of treatment initiation of the updated edition of the AIDS Diagnostic and Treatment Guidelines (Guidelines) significantly prolonged the survival time of people living with HIV/AIDS.

Long-Term Benefits from Early Antiretroviral Therapy Initiation in HIV Infection

BACKGROUND

For people with HIV and CD4+ counts >500 cells/mm3, early initiation of antiretroviral therapy (ART) reduces serious AIDS and serious non-AIDS (SNA) risk compared with deferral of treatment until CD4+ counts are <350 cells/mm3. Whether excess risk of AIDS and SNA persists once ART is initiated for those who defer treatment is uncertain.

METHODS

The Strategic Timing of AntiRetroviral Treatment (START) trial, as previously reported, randomly assigned 4684 ART-naive HIV-positive adults with CD4+ counts .500 cells/mm3 to immediate treatment initiation after random assignment (n = 2325) or deferred treatment (n= 2359). In 2015, a 57% lower risk of the primary end point (AIDS, SNA, or death) for the immediate group was reported, and the deferred group was offered ART. This article reports the follow-up that continued to December 31, 2021. Cox proportional-hazards models were used to compare hazard ratios for the primary end point from randomization through December 31, 2015, versus January 1, 2016, through December 31, 2021.

RESULTS

Through December 31, 2015, approximately 7 months after the cutoff date from the previous report, the median CD4+ count was 648 and 460 cells/mm3 in the immediate and deferred groups, respectively, at treatment initiation. The percentage of follow-up time spent taking ART was 95% and 36% for the immediate and deferred groups, respectively, and the time-averaged CD4+ difference was 199 cells/mm3. After January 1, 2016, the percentage of follow-up time on treatment was 97.2% and 94.1% for the immediate and deferred groups, respectively, and the CD4+ count difference was 155 cells/mm3. After January 1, 2016, a total of 89 immediate and 113 deferred group participants experienced a primary end point (hazard ratio of 0.79 [95% confidence interval, 0.60 to 1.04] versus hazard ratio of 0.47 [95% confidence interval, 0.34 to 0.65; P<0.001]) before 2016 (P=0.02 for hazard ratio difference).

CONCLUSIONS

Among adults with CD4+ counts >500 cells/mm3, excess risk of AIDS and SNA associated with delaying treatment initiation was diminished after ART initiation, but persistent excess risk remained. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Sustained virological response after treatment with direct antiviral agents in individuals with HIV and hepatitis C co-infection

INTRODUCTION

Randomized trials and observational studies have consistently reported rates of sustained virological response (SVR), equivalent to hepatitis C virus (HCV) cure, as high as 95% following treatment with direct-acting antiviral (DAA) treatment in individuals with HIV and HCV co-infection. However, large studies assessing whether SVR rates differ according to demographic and clinical strata are lacking. Additionally, the SVR rates reported in the literature were typically computed in non-random samples of individuals with available post-DAA HCV-RNA measures. Here, we aimed to estimate the probability of SVR after DAA treatment initiation in persons with HIV and HCV co-infection overall and by demographic and clinical characteristics with and without adjustment for missing HCV-RNA testing.

METHODS

We included adults with HIV-HCV co-infection who received DAA treatment between 2014 and 2020 in HepCAUSAL, an international collaboration of cohorts from Europe and North America. We estimated the proportions of DAA recipients who had documented SVR (defined as an undetectable HCV-RNA at least 12 weeks after the end of DAA treatment) overall and by strata defined by age, sex, presence of cirrhosis, calendar period, mode of HIV acquisition, CD4 cell count and HCV genotype at DAA treatment. We then compared these rates with those obtained using the parametric g-formula to impute SVR status for individuals with no SVR assessment.

RESULTS AND DISCUSSION

A total of 4527 individuals who initiated DAA treatment (88% males, median [IQR] age 56 [50, 62] years) were included. Of the total of 642 (14%) individuals had no HCV-RNA test on or after 12 weeks after the end of treatment. The overall observed and g-formula imputed SVR rates were 93% (95% CI 93, 94) and 94% (95% CI 92, 95), respectively. SVR estimates were similarly high across all strata. A substantial proportion of individuals who received DAA treatment were never assessed for SVR post-DAA and strategies for more systematic routine HCV-RNA testing should be considered.

CONCLUSIONS

Our estimates with and without adjustment for missing HCV-RNA testing indicate SVR rates of approximately 95%, like those reported in clinical trials.

Motivations and Barriers to Routine HIV Testing Among Men Who Have Sex with Men in New York City

In-depth qualitative interviews explored the experiences and understandings of men 18-39 years old who have sex with men that could facilitate or prevent HIV testing and routine HIV testing. For many men who tested frequently, testing and routine testing were motivated by awareness of the benefit of prompt treatment; public health and provider encouragement to test periodically; responsibility towards sexual partners; and wanting to share a recent HIV-negative test result when seeking sex online. For some men, any testing was impeded by anxiety around possible HIV diagnosis that made testing a stressful occasion that required time and energy to prepare for. This anxiety was often compounded by stigma related to sex between men, having condomless sex, or having HIV. Routine testing could be further stigmatized as some men felt judged by testing providers or partners if they asked for a test or said they tested frequently. We describe efforts to promote testing and routine testing by countering fear and stigma associated with HIV and testing.

MULTIPLY ROBUST ESTIMATORS OF CAUSAL EFFECTS FOR SURVIVAL OUTCOMES

Multiply robust estimators of the longitudinal g-formula have recently been proposed to protect against model misspecification better than the standard augmented inverse probability weighted estimator (Rotnitzky et al., 2017; Luedtke et al., 2018). These multiply robust estimators ensure consistency if one of the models for the treatment process or outcome process is correctly specified at each time point. We study the multiply robust estimators of Rotnitzky et al. (2017) in the context of a survival outcome. Specifically, we compare various estimators of the g-formula for survival outcomes in order to 1) understand how the estimators may be related to one another, 2) understand each estimator's robustness to model misspecification, and 3) construct estimators that can be more efficient than others in certain model misspecification scenarios. We propose a modification of the multiply robust estimators to gain efficiency under misspecification of the outcome model by using calibrated propensity scores over non-calibrated propensity scores at each time point. Theoretical results are confirmed via simulation studies, and a practical comparison of these estimators is conducted through an application to the US Veterans Aging Cohort Study.

Effect of Late Testing and Antiretroviral Treatment on Mortality Among People Living With HIV in the Era of Treat-All in Guangdong Province, China, 1992–2018: A Cohort Study

Late testing and antiretroviral therapy (ART) prevailed among people living with HIV (PLHIV) and impacted the benefit of immediate ART. This study aimed to identify the benefit of the test-and-immediate-treat policy in China, the effect of immediate ART, and the influence of late testing and ART on the whole PLHIV in Guangdong Province, China. We designed two tendency analyses in aggregative form and two cohorts (surveillance and ART cohort) in individuals' perspectives based on the HIV/AIDS Comprehensive Response Information Management System. Two interrupted time series models were conducted for tendency analysis from 2009 to 2018 to explore the all-cause and short-term mortality decrease after the test-and-immediate-treat policy. A time-dependent Cox model was performed for the surveillance cohort from 1992 to 2018 and a joint model was utilized for the ART cohort to identify the effect of immediate ART and the influence of late testing and ART on death. The tendency analysis included 324,914 and 68,679 person-year for all-cause/short-term mortality. A total of 49,289 and 26,287 PLHIV were recruited in the surveillance and ART cohort with 5,557 and 459 deaths, respectively. The short-term mortality dropped from 4.69 cases/100 person-year in January 2009 to 0.35 cases/100 person-year in December 2018 (standardized rate). The all-cause mortality saw a decreasing trend from 1.46 cases/100 person-year in January 2009 to 0.14 cases/100 person-year in December 2018 (standardized rate). The tendency analysis showed a significant short-term mortality slope decrease after the test-and-immediate-treat policy (P = 0.024). From the surveillance cohort, late testing, in general, was a risk factor for all-cause mortality [hazard ratio (HR) = 1.330, 95% CI, 1.250, 1.416]. ART cohort showed higher hazards of all-cause mortality among PLHIV with no late testing, but late ART (HR = 1.690, 95% CI, 1.166, 2.451) and both the late testing and late ART (HR = 1.335, 95% CI, 1.042, 1.710). Immediate ART might decrease the hazard of all-cause death though it is insignificant (HR = 0.923, 95% CI: 0.755, 1.129) in the ART cohort. The test-and-immediate-test policy brought benefit to PLHIV. We should enlarge HIV testing using comprehensive approaches to decrease late testing and ART and increase the benefit of immediate ART.

Benchmarking Observational Analyses Before Using Them to Address Questions Trials Do Not Answer: An Application to Coronary Thrombus Aspiration

To increase confidence in the use of observational analyses when addressing effectiveness questions beyond those addressed by randomized trials, one can first benchmark the observational analyses against existing trial results. We used Swedish registry data to emulate a target trial similar to the Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia (TASTE) randomized trial, which found no difference in the risk of death or myocardial infarction by 1 year with or without thrombus aspiration among individuals with ST-elevation myocardial infarction. We benchmarked the emulation against the trial at 1 year and then extended the emulation's follow-up to 3 years and estimated effects in subpopulations underrepresented in the trial. As in the TASTE trial, the observational analysis found no differences in risk of outcomes by 1 year between groups (risk difference = 0.7 (confidence interval, -0.7, 2.0) and -0.2 (confidence interval, -1.3, 1.0) for death and myocardial infarction, respectively), so benchmarking was considered successful. We additionally showed no difference in risk of death or myocardial infarction by 3 years, or within subpopulations by 1 year. Benchmarking against an index trial before using observational analyses to answer questions beyond those the trial could address allowed us to explore whether the observational data can be trusted to deliver valid estimates of treatment effects.

Estimating the causal effect of treatment with direct-acting antivirals on kidney function among individuals with hepatitis C virus infection

Background

Direct-acting antivirals (DAA) are highly effective at treating Hepatitis C virus (HCV) infection, with a cure rate >95%. However, the effect of DAAs on kidney function remains debated.

Methods

We analyzed electronic health record data for DAA-naive patients with chronic HCV infection engaged in HCV care at Boston Medical Center between 2014 and 2018. We compared the following hypothetical interventions using causal inference methods: 1) initiation of DAA and 2) no DAA initiation. For patients with normal kidney function at baseline (eGFR>90 ml/min/1.73m²), we estimated and compared the risk for reaching Stage 3 chronic kidney disease (CKD) (eGFR≤60 ml/min/1.73m²) under each intervention. For patients with baseline CKD Stages 2–4 (15<eGFR≤90 ml/min/1.73m²), we estimated and compared the mean change in eGFR at 2 years after baseline under each intervention. We used the parametric g-formula to adjust our estimates for baseline and time-varying confounders.

Results

First, among 1390 patients with normal kidney function at baseline the estimated 2-year risk difference (95% CI) of reaching Stage 3 CKD for DAA initiation versus no DAA was -1% (-3, 2). Second, among 733 patients with CKD Stage 2–4 at baseline the estimated 2-year mean difference in change in eGFR for DAA initiation versus no DAA therapy was -3 ml/min/1.73m² (-8, 2).

Conclusions

We found no effect of DAA initiation on kidney function, independent of baseline renal status. This suggests that DAAs may not be nephrotoxic; furthermore, in the short-term, HCV clearance may not improve CKD.

Revisiting the g-null Paradox

The (noniterative conditional expectation) parametric g-formula is an approach to estimating causal effects of sustained treatment strategies from observational data. An often-cited limitation of the parametric g-formula is the g-null paradox: a phenomenon in which model misspecification in the parametric g-formula is guaranteed in some settings consistent with the conditions that motivate its use (i.e., when identifiability conditions hold and measured time-varying confounders are affected by past treatment). Many users of the parametric g-formula acknowledge the g-null paradox as a limitation when reporting results but still require clarity on its meaning and implications. Here, we revisit the g-null paradox to clarify its role in causal inference studies. In doing so, we present analytic examples and a simulation-based illustration of the bias of parametric g-formula estimates under the conditions associated with this paradox. Our results highlight the importance of avoiding overly parsimonious models for the components of the g-formula when using this method.

Avoiding Time-Related Biases: A Feasibility Study on Antidiabetic Drugs and Pancreatic Cancer Applying the Parametric g-Formula to a Large German Healthcare Database

Purpose

Investigating intended or unintended effects of sustained drug use is of high clinical relevance but remains methodologically challenging. This feasibility study aims to evaluate the usefulness of the parametric g-formula within a target trial for application to an extensive healthcare database in order to address various sources of time-related biases and time-dependent confounding.

Patients and Methods

Based on the German Pharmacoepidemiological Research Database (GePaRD), we estimated the pancreatic cancer incidence comparing two hypothetical treatment strategies for type 2 diabetes mellitus (T2DM), i.e., (A) sustained metformin monotherapy vs (B) combination therapy with DPP-4 inhibitors after one year metformin monotherapy. We included 77,330 persons with T2DM who started metformin therapy at baseline between 2005 and 2011. Key aspects for avoiding time-related biases and time-dependent confounding were the emulation of a target trial over a 7-year follow-up period and application of the parametric g-formula.

Results

Over the 7-year follow-up period, 652 out of the 77,330 study subjects had a diagnosis of pancreatic cancer. Assuming no unobserved confounding, we found evidence that the metformin/DPP-4i combination therapy increased the risk of pancreatic cancer compared to a sustained metformin monotherapy (risk ratio: 1.47; 95% bootstrap CI: 1.07–1.94). The risk ratio decreased in sensitivity analyses addressing protopathic bias.

Conclusion

While protopathic bias could not fully be ruled out, and computational challenges necessitated compromises in the analysis, the g-formula and target trial emulation proved useful: Self-inflicted biases were avoided, observed time-varying confounding was adjusted for, and the estimated risks have a clear causal interpretation.

Timeliness of antiretroviral therapy initiation in the era before universal treatment

We assessed the prevalence and factors related to the time to antiretroviral (ART) initiation among persons who entered HIV care and subsequently started ART in Croatia from 2005 to 2014. Included were patients ≥ 18 years, the follow-up ended on Dec/31/2017. 628 patients were included into the study 91.9% were men; median age was 36.1 (Q1-Q3: 29.6-43.8) years. Rapid (within 7 days of diagnosis) ART initiation was observed in 21.8% patients, 49.8% initiated ART within 30 days, 21.7% and 28.5% had intermediate (31 days-1 year) and late initiation (> 1 year), respectively. Of 608 patients that achieved an undetectable viral load, 94% had a plasma HIV-1 RNA < 50 copies/ml at last measurement after a median follow-up of 5.2 years. On quantile regression analysis, calendar year of entry into care, and markers of more advanced HIV disease (higher viral load, lower CD4 cell count and clinical AIDS) were significantly associated with earlier ART initiation. Early ART was not related to a gap in care afterwards at all quantiles. In conclusion, a significant proportion of patients started ART early in Croatia in 2005-2014. Early ART initiation led to durable viral load suppression and was not associated with a subsequent gap in care.

A scoping review of studies using observational data to optimise dynamic treatment regimens

BACKGROUND

Dynamic treatment regimens (DTRs) formalise the multi-stage and dynamic decision problems that clinicians often face when treating chronic or progressive medical conditions. Compared to randomised controlled trials, using observational data to optimise DTRs may allow a wider range of treatments to be evaluated at a lower cost. This review aimed to provide an overview of how DTRs are optimised with observational data in practice.

METHODS

Using the PubMed database, a scoping review of studies in which DTRs were optimised using observational data was performed in October 2020. Data extracted from eligible articles included target medical condition, source and type of data, statistical methods, and translational relevance of the included studies.

RESULTS

From 209 PubMed abstracts, 37 full-text articles were identified, and a further 26 were screened from the reference lists, totalling 63 articles for inclusion in a narrative data synthesis. Observational DTR models are a recent development and their application has been concentrated in a few medical areas, primarily HIV/AIDS (27, 43%), followed by cancer (8, 13%), and diabetes (6, 10%). There was substantial variation in the scope, intent, complexity, and quality between the included studies. Statistical methods that were used included inverse-probability weighting (26, 41%), the parametric G-formula (16, 25%), Q-learning (10, 16%), G-estimation (4, 6%), targeted maximum likelihood/minimum loss-based estimation (4, 6%), regret regression (3, 5%), and other less common approaches (10, 16%). Notably, studies that were primarily intended to address real-world clinical questions (18, 29%) tended to use inverse-probability weighting and the parametric G-formula, relatively well-established methods, along with a large amount of data. Studies focused on methodological developments (45, 71%) tended to be more complicated and included a demonstrative real-world application only.

CONCLUSIONS

As chronic and progressive conditions become more common, the need will grow for personalised treatments and methods to estimate the effects of DTRs. Observational DTR studies will be necessary, but so far their use to inform clinical practice has been limited. Focusing on simple DTRs, collecting large and rich clinical datasets, and fostering tight partnerships between content experts and data analysts may result in more clinically relevant observational DTR studies.

Rapid Start of Antiretroviral Therapy in Youth Diagnosed with HIV Infection

BACKGROUND

Guidelines for the use of antiretroviral agents in adults and adolescents with HIV recommend that antiretroviral therapy (ART) be started as soon as possible. While rapid initiation of ART in adults with HIV has been well-described, there is relatively little information describing this approach for youth.

METHODS

On April 1, 2018, St. Jude Children's Research Hospital began offering ART to youth with HIV infection at their first clinic visit. We report the results of a quality improvement initiative that compared patients who offered ART at their first visit to a historical cohort of patients who initiated ART at a subsequent visit. Demographic, HIV biomarker, and visit information were abstracted from medical records, described and compared using univariate statistical methods.

RESULTS

There were 124 ART-naive youth (median age 19 years, 91% male, 94% black) first seen during the indicated time period. A total of 54 patients were in the baseline cohort and 70 patients were in the rapid start cohort. 90% of youth in the rapid start cohort started ART on their first clinic visit. Time from first clinic visit to undetectable viral load was significantly higher in the baseline cohort compared with the rapid start cohort (median 54 vs. 41 days; P = 0.01). Retention in care 12 months following the first clinic visit was comparable and overall high (>80%).

CONCLUSIONS

Starting ART-naïve youth with HIV infection on ART at their first clinic visit is feasible, has high acceptance, leads to faster viral load suppression, and is associated with high retention in care.

Effects of daily treatment with acid suppressants for stress ulcer prophylaxis on risk of ventilator-associated events

OBJECTIVE

To estimate the effects of continuous daily treatment with different acid suppressants on the risk of ventilator-associated events in critically ill patients.

DESIGN

Retrospective cohort study.

PATIENTS

Adult critically ill patients who underwent mechanical ventilation for ≥3 days during an inpatient admission between January 2006 and December 2014.

METHODS

We estimated the 30-day cumulative risk ratios (RRs) for ventilator-associated events comparing daily proton pump inhibitor (PPI) versus daily histamine-2-receptor antagonist (H2RA) strategies while controlling for time-fixed and time-varying confounding and accounting for competing events.

RESULTS

Of 6,133 patients, on ventilation day 3, 58.8% received H2RAs, 26.1% received PPIs, and 4.1% received sucralfate. Patients frequently changed treatment throughout follow-up. Among 4,595 patients receiving PPIs or H2RAs on day 3, we found no differences in risk estimates for ventilator mortality and extubation alive comparing daily PPI versus daily H2RA strategies: RR, mortality, 1.03 (95% CI, 0.89-1.22); extubation alive, 1.00 (95% CI, 0.96-1.03). We found similar results after accounting for PPI dose. For possible ventilator-associated pneumonia (PVAP) and infection-related ventilator-associated complication (IVAC), point estimates were larger, but the 95% CIs crossed 1.0: RR PVAP, 1.25 (95% CI, 0.80-1.94); IVAC, 0.89 (95% CI, 0.64-1.17). The magnitude of effect estimates depended on PPI dose. The RR for PVAP, high-dose PPI versus H2RA, was 1.53 (95% CI, 0.82-2.51), and for low-dose PPI versus H2RA, the RR was 0.97 (95% CI, 0.47-1.63). For IVAC, high-dose PPI versus H2RA, the RR was 1.01 (95% CI, 0.66-1.42), and for low-dose PPI versus H2RA, the RR was 0.78 (95% CI, 0.50-1.11).

CONCLUSIONS

We estimated no effect of daily PPI versus daily H2RA on risk of mortality or extubation alive in critically ill patients. Further investigation with larger samples is warranted for PVAP and IVAC.

Parametric g-formula implementations for causal survival analyses

The g-formula can be used to estimate the survival curve under a sustained treatment strategy. Two available estimators of the g-formula are noniterative conditional expectation and iterative conditional expectation. We propose a version of the iterative conditional expectation estimator and describe its procedures for deterministic and random treatment strategies. Also, because little is known about the comparative performance of noniterative and iterative conditional expectation estimators, we explore their relative efficiency via simulation studies. Our simulations show that, in the absence of model misspecification and unmeasured confounding, our proposed iterative conditional expectation estimator and the noniterative conditional expectation estimator are similarly efficient, and that both are at least as efficient as the classical iterative conditional expectation estimator. We describe an application of both noniterative and iterative conditional expectation to answer "when to start" treatment questions using data from the HIV-CAUSAL Collaboration.

Incorporation of the rapid HIV test in a sexually-transmitted disease clinic in Buenos Aires: Dramatic increase in the frequency of HIV diagnosis

Improving access to diagnosis constitutes a key step in the control of the Human immunodeficiency virus (HIV)/AIDS epidemic. Rapid testing is increasingly gaining interest as a powerful diagnostic tool to achieve this goal. The purpose of this study was to implement the rapid HIV test (RHT) in a clinical setting in order to evaluate its effectiveness in increasing HIV diagnosis and patient linkage to the healthcare system. The RHT was offered to all patients attending a sexually-transmitted disease clinic in the City of Buenos Aires between March and December 2015. A total of 593 RHT were performed. The implementation of the RHT yielded an increase in frequency of diagnosis from 6.9% to 31.4% (p<0.001). The first steps of the care cascade showed high retention rates around 90%. RHT yielded an HIV prevalence of 6.3% (95% CI: 4.2-8.5) in this population. HIV prevalence tended to be higher in individuals with no previous HIV testing (p=0.09). Linkage to the healthcare system was associated with a higher probability of having been tested for HIV (p=0.008). The incorporation of the RHT resulted in a high retention of patients and an increase in both frequency of diagnosis and results reception when compared to the classic methodology.

Nationwide Cohort Study of Antiretroviral Therapy Timing: Treatment Dropout and Virological Failure in China, 2011-2015

Background

People living with human immunodeficiency virus (PLWH) are still being diagnosed late, rendering the benefits of "early" antiretroviral therapy (ART) unattainable. Therefore, we aimed to evaluate the benefits of "immediate" ART.

Methods

A nationwide cohort of PLWH in China who initiated ART January 1, 2011, to December 31, 2014 and had baseline CD4 results >200 cells/μL were censored at 12 months, dropout, or death, whichever came first. Treatment dropout and virological failure (viral load ≥400 copies/mL) were measured. Determinants were assessed by Cox and log-binomial regression.

Results

The cohort included 123605 PLWH. The ≤30 days group had a significantly lower treatment dropout rate of 6.72%, compared to 8.91% for the 91-365 days group and to 12.64% for the >365 days group. The ≤30 days group also had a significantly lower virological failure rate of 5.45% (31-90 days: 7.39%; 91-365 days: 9.64%; >365 days: 12.67%). Greater risk of dropout (91-365 days: adjusted hazard ratio [aHR] = 1.33, 95% confidence interval [CI] = 1.25-1.42; >365 days: aHR = 1.55, CI = 1.47-1.54), and virological failure (31-90 days: adjusted risk ratio [aRR] = 1.35, CI = 1.26-1.45; 91-365 days: aRR = 1.66, CI = 1.55-1.78; >365 days: aRR = 1.85, CI = 1.74-1.97) were observed for those who delayed treatment.

Conclusions

ART within 30 days of HIV diagnosis was associated with significantly reduced risk of treatment failure, highlighting the need to implement test-and-immediately-treat policies.

Immediate Antiretroviral Therapy Decreases Mortality Among Patients With High CD4 Counts in China: A Nationwide, Retrospective Cohort Study

Background

Clinical trials have demonstrated that immediate initiation of antiretroviral therapy (ART) reduces AIDS-related morbidity and mortality. We tested the hypothesis that initiating ART ≤30 days after human immunodeficiency virus (HIV) diagnosis would be associated with reduced mortality among people living with HIV (PLWH) with CD4 counts >500 cells/μL.

Methods

PLWH enrolled in the Chinese National HIV Information System between January 2012 and June 2014 with CD4 counts >500 cells/μL were followed for 12 months. Cox proportional hazards model was used to determine hazard ratios (HRs) for PLWH who initiated ART after HIV diagnosis. ART initiation was treated as a time-dependent variable.

Results

We enrolled 34581 PLWH with CD4 >500 cells/μL; 1838 (5.3%) initiated ART ≤30 days after diagnosis (immediate ART group), and 19 deaths were observed with a mortality rate of 1.04 per 100 person-years (PY). Fifty-eight deaths were documented among the 5640 PLWH in the delayed ART group with a mortality rate of 2.25 per 100 PY. There were 713 deaths among the 27103 PLWH in the no ART group with a mortality rate of 2.39 per 100 PY. After controlling for potential confounding factors, ART initiation at ≤30 days (adjusted HR, 0.37 [95% confidence interval, .23–.58]) was a statistically significant protective factor.

Conclusions

We found that immediate ART is associated with a 63% reduction in overall mortality among PLWH with CD4 counts >500 cells/μL in China, supporting the recommendation to initiate ART immediately following HIV diagnosis.

Refining the Association Between Body Mass Index and Atrial Fibrillation: G-Formula and Restricted Mean Survival Times

Background

Previous studies assessing the association between body mass index (BMI) and atrial fibrillation (AF) did not account for time‐varying covariates, which may be affected by previous BMI. We illustrate how the g‐formula can account for time‐varying confounding.

Methods and Results

We included 4392 participants from the Framingham Heart Study who were AF free at ages 45 to 55 years, and followed them for up to 20 years. We estimated hazard ratios (HRs) comparing time‐varying nonobese versus obese with Cox models. We used the g‐formula to compare nonobese versus obese and 10% annual decrease in BMI (until normal weight is reached) versus natural course. We estimated HRs and differences in restricted mean survival times, the mean difference in time alive and AF free. We adjusted for sex, age, and time‐varying risk factors. Cox models indicated that nonobese participants had a decreased rate of AF versus obese participants (HR, 0.83; 95% CI, 0.72–0.97). G‐formula analyses comparing everyone had they been nonobese versus obese yielded stronger associations (HR, 0.73; 95% CI, 0.58–0.91). The restricted mean survival time was 19.22 years had everyone been nonobese and 19.03 years had everyone been obese (difference, 2.25 months; 95% CI, −0.66 to 5.16). When assessing a 10% annual decrease in BMI, the association was weaker (HR 0.96; 95% CI, 0.86–1.08).

Conclusions

Decreased BMI was associated with a lower rate of AF after accounting for time‐varying covariates that depend on previous exposure using the g‐formula, which Cox models cannot accommodate. Absolute measures like the restricted mean survival time difference offer context to relative measures of association.

Effect Estimates in Randomized Trials and Observational Studies: Comparing Apples With Apples

Effect estimates from randomized trials and observational studies might not be directly comparable because of differences in study design, other than randomization, and in data analysis. We propose a 3-step procedure to facilitate meaningful comparisons of effect estimates from randomized trials and observational studies: 1) harmonization of the study protocols (eligibility criteria, treatment strategies, outcome, start and end of follow-up, causal contrast) so that the studies target the same causal effect, 2) harmonization of the data analysis to estimate the causal effect, and 3) sensitivity analyses to investigate the impact of discrepancies that could not be accounted for in the harmonization process. To illustrate our approach, we compared estimates of the effect of immediate with deferred initiation of antiretroviral therapy in individuals positive for the human immunodeficiency virus from the Strategic Timing of Antiretroviral Therapy (START) randomized trial and the observational HIV-CAUSAL Collaboration.

Screening for HIV Infection in Asymptomatic, Nonpregnant Adolescents and Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Untreated HIV infection can result in significant morbidity, mortality, and HIV transmission. A 2012 review for the US Preventive Services Task Force (USPSTF) found antiretroviral therapy (ART) associated with improved clinical outcomes and decreased transmission risk in persons with CD4 cell counts less than 500/mm3.

OBJECTIVE

To update the 2012 review on HIV screening to inform the USPSTF.

DATA SOURCES

Ovid MEDLINE, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews from 2012 to June 2018, with surveillance through January 2019.

STUDY SELECTION

Nonpregnant individuals 12 years and older; randomized clinical trials (RCTs) and controlled observational studies of screening vs no screening, alternative screening strategies, earlier vs later initiation of ART, and long-term harms of ART.

DATA EXTRACTION AND SYNTHESIS

One investigator abstracted data; a second checked accuracy. Two investigators independently rated study quality.

MAIN OUTCOMES AND MEASURES

Mortality, AIDS events, quality of life, function, and HIV transmission; harms of screening and long-term (≥2 years) harms of ART; screening yield.

RESULTS

Eighteen new studies (5 RCTs, 11 cohort studies, and 2 systematic reviews; N = 266 563) were included, and 11 studies (2 RCTs and 9 cohort studies; N = 218 542) were carried forward from the prior USPSTF report. No study directly evaluated effects of HIV screening vs no screening on clinical outcomes or harms, or the yield of alternative screening strategies. Two newly identified RCTs conducted completely or partially in low-resource settings found ART initiation at CD4 cell counts greater than 500/mm3 associated with lower risk of a composite outcome of mortality, AIDS-defining events, or serious non-AIDS events (relative risk [RR], 0.44 [95% CI, 0.31-0.63] and RR, 0.57 [95% CI, 0.35-0.95]); results were consistent with those from a large observational study. Early ART was not associated with increased risk of cardiovascular events. Early ART initiation was associated with sustained reduction in risk of HIV transmission at 5.5 years (RR, 0.07 [95% CI, 0.02-0.22] for linked transmission). New evidence regarding the association between abacavir use and risk of cardiovascular events was inconsistent. Certain antiretroviral regimens were associated with increased risk of long-term neuropsychiatric, renal, hepatic, and bone adverse events.

CONCLUSIONS AND RELEVANCE

In nonpregnant adolescents and adults there was no direct evidence on the clinical benefits and harms of screening for HIV infections vs no screening, or the yield of repeat or alternative screening strategies. New evidence extends effectiveness of ART to asymptomatic individuals with CD4 cell counts greater than 500/mm3 and shows sustained reduction in risk of HIV transmission at longer-term follow-up, although certain ART regimens may be associated with increased risk of long-term harms.

Immediate antiviral therapy for HIV-infected persons faces with various obstacles

Human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) ranks eighth in the global burden of disease, making seriously threatens to global health. Given there is not yet a cure for HIV infection, antiretroviral therapy (ART) holds a key role not only in improving the prognosis of the patients, but also reducing the risk of HIV transmission. The immediate initiation of ART has been recommended in domestic and foreign policies and guidelines, yet the implementation of this strategy is not satisfactory. In developing countries and even in some developed countries, it still takes a long time for patients to go from the diagnosis of HIV infection to the acceptance of ART. Clarifying the obstacles to the implementation of immediate ART and finding strategies to cope with them have emerged as key problems in response to HIV/AIDS.

Screening for HIV Infection: US Preventive Services Task Force Recommendation Statement

IMPORTANCE

Approximately 1.1 million persons in the United States are currently living with HIV, and more than 700 000 persons have died of AIDS since the first cases were reported in 1981. There were approximately 38 300 new diagnoses of HIV infection in 2017. The estimated prevalence of HIV infection among persons 13 years and older in the United States is 0.4%, and data from the Centers for Disease Control and Prevention show a significant increase in HIV diagnoses starting at age 15 years. An estimated 8700 women living with HIV give birth each year in the United States. HIV can be transmitted from mother to child during pregnancy, labor, delivery, and breastfeeding. The incidence of perinatal HIV infection in the United States peaked in 1992 and has declined significantly following the implementation of routine prenatal HIV screening and the use of effective therapies and precautions to prevent mother-to-child transmission.

OBJECTIVE

To update the 2013 US Preventive Services Task Force (USPSTF) recommendation on screening for HIV infection in adolescents, adults, and pregnant women.

EVIDENCE REVIEW

The USPSTF reviewed the evidence on the benefits and harms of screening for HIV infection in nonpregnant adolescents and adults, the yield of screening for HIV infection at different intervals, the effects of initiating antiretroviral therapy (ART) at a higher vs lower CD4 cell count, and the longer-term harms associated with currently recommended ART regimens. The USPSTF also reviewed the evidence on the benefits (specifically, reduced risk of mother-to-child transmission of HIV infection) and harms of screening for HIV infection in pregnant persons, the yield of repeat screening for HIV at different intervals during pregnancy, the effectiveness of currently recommended ART regimens for reducing mother-to-child transmission of HIV infection, and the harms of ART during pregnancy to the mother and infant.

FINDINGS

The USPSTF found convincing evidence that currently recommended HIV tests are highly accurate in diagnosing HIV infection. The USPSTF found convincing evidence that identification and early treatment of HIV infection is of substantial benefit in reducing the risk of AIDS-related events or death. The USPSTF found convincing evidence that the use of ART is of substantial benefit in decreasing the risk of HIV transmission to uninfected sex partners. The USPSTF also found convincing evidence that identification and treatment of pregnant women living with HIV infection is of substantial benefit in reducing the rate of mother-to-child transmission. The USPSTF found adequate evidence that ART is associated with some harms, including neuropsychiatric, renal, and hepatic harms, and an increased risk of preterm birth in pregnant women. The USPSTF concludes with high certainty that the net benefit of screening for HIV infection in adolescents, adults, and pregnant women is substantial.

CONCLUSIONS AND RECOMMENDATION

The USPSTF recommends screening for HIV infection in adolescents and adults aged 15 to 65 years. Younger adolescents and older adults who are at increased risk of infection should also be screened. (A recommendation) The USPSTF recommends screening for HIV infection in all pregnant persons, including those who present in labor or at delivery whose HIV status is unknown. (A recommendation).

Two decades of surveillance data show late presentation among a diverse group of women diagnosed with HIV in Victoria, Australia

OBJECTIVE

To develop an HIV response suited to women and to inform appropriate services, we describe the characteristics of women diagnosed and living with HIV using 22 years of high-quality surveillance data.

METHODS

Data on women newly diagnosed with HIV between 1994 and 2016 and women living with diagnosed HIV in Victoria at 31 December 2016 were extracted from the Victorian Public Health Surveillance System. Descriptive analysis by place of birth was performed and Poisson regression used to assess trends over time.

RESULTS

There were 465 new diagnoses among women in Victoria between 1994 and 2016 and 613 women living with HIV in 2016. Women were diagnosed late, and frequently reported no HIV testing history, AIDS-defining illness or other symptoms of HIV at diagnosis. These indicators of delayed diagnosis were even greater for non-Australian-born women. Conclusions and implications for public health: For Victoria to reach the ambitious targets for diagnosis, treatment and viral suppression in 95% of people living with HIV, prevention programs and efforts to increase early diagnosis as well as support services must consider the epidemiology and diversity of women.

Serious Non-AIDS Conditions in HIV: Benefit of Early ART

PURPOSE OF REVIEW

Optimal control of HIV can be achieved by early diagnosis followed by the initiation of antiretroviral therapy (ART). Two large randomised trials (TEMPRANO and START) have recently been published documenting the clinical benefits to HIV-positive adults of early ART initiation. Main findings are reviewed with a focus on serious non-AIDS (SNA) conditions.

RECENT FINDINGS

Data from the two trials demonstrated that initiating ART early in the course of HIV infection resulted in marked reductions in the risk of opportunistic diseases and invasive bacterial infections. This indicates that HIV causes immune impairment in early infection that is remedied by controlling viral replication. Intriguingly, in START, a marked reduction in risk of cancers, both infection-related and unrelated types of cancers, was observed. Like the findings for opportunistic infections, this anti-cancer effect of early ART shows how the immune system influences important pro-oncogenic processes. In START, there was also some evidence suggesting that early ART initiation preserved kidney function, although the clinical consequence of this remains unclear. Conversely, while no adverse effects were evident, the trials did not demonstrate a clear effect on metabolic-related disease outcomes, pulmonary disease, or neurocognitive function. HIV causes immune impairment soon after acquisition of infection. ART reverses this harm at least partially. The biological nature of the immune impairment needs further elucidation, as well as mechanisms and clinical impact of innate immune activation. Based on the findings from TEMPRANO and START, and because ART lowers the risk of onward transmission, ART initiation should be offered to all persons following their diagnosis of HIV.

Validation of HIV-infected cohort identification using automated clinical data in the Department of Veterans Affairs

OBJECTIVES

The US Department of Veterans Affairs (VA) is the largest integrated health care provider for HIV-infected patients in the USA. VA data for HIV-specific clinical and quality improvement research are an important resource. We sought to determine the accuracy of using the VA Corporate Data Warehouse (CDW), a fully automated medical records database for all VA users nationally, to identify HIV-infected patients compared with a gold-standard VA HIV Clinical Case Registry (CCR).

METHODS

We assessed the test performance characteristics of each of our CDW criteria-based algorithms (presence of one, two or all of the following: diagnostic codes for HIV, positive HIV laboratory tests, and prescription for HIV medication) by calculating their sensitivity (proportion of HIV-positive patients in the CCR accurately detected as HIV-positive by the CDW algorithm) and positive predictive value (PPV; the proportion of patients identified by the CDW algorithm who were classified as HIV-positive from the CCR).

RESULTS

We found that using a CDW algorithm requiring two of three HIV diagnostic criteria yielded the highest sensitivity (95.2%) with very little trade-off in PPV (93.5%).

CONCLUSIONS

A two diagnostic criteria-based algorithm can be utilized to accurately identify HIV-infected cohorts seen in the nationwide VA health care system.

HIV virologic failure and its predictors among HIV-infected adults on antiretroviral therapy in the African Cohort Study

INTRODUCTION

The 2016 WHO consolidated guidelines on the use of antiretroviral drugs defines HIV virologic failure for low and middle income countries (LMIC) as plasma HIV-RNA ≥ 1000 copies/mL. We evaluated virologic failure and predictors in four African countries.

MATERIALS AND METHODS

We included HIV-infected participants on a WHO recommended antiretroviral therapy (ART) regimen and enrolled in the African Cohort Study between January 2013 and October 2017. Studied outcomes were virologic failure (plasma HIV-RNA ≥ 1000 copies/mL at the most recent visit), viraemia (plasma HIV-RNA ≥ 50 copies/mL at the most recent visit); and persistent viraemia (plasma HIV-RNA ≥ 50 copies/mL at two consecutive visits). Generalized linear models were used to estimate relative risks with their 95% confidence intervals.

RESULTS

2054 participants were included in this analysis. Viraemia, persistent viraemia and virologic failure were observed in 396 (19.3%), 160 (7.8%) and 184 (9%) participants respectively. Of the participants with persistent viraemia, only 57.5% (92/160) had confirmed virologic failure. In the multivariate analysis, attending clinical care site other than the Uganda sitebeing on 2nd line ART (aRR 1.8, 95% CI 1·28-2·66); other ART combinations not first line and not second line (aRR 3.8, 95% CI 1.18-11.9), a history of fever in the past week (aRR 3.7, 95% CI 1.69-8.05), low CD4 count (aRR 6.9, 95% CI 4.7-10.2) and missing any day of ART (aRR 1·8, 95% CI 1·27-2.57) increased the risk of virologic failure. Being on 2nd line therapy, the site where one receives care and CD4 count < 500 predicted viraemia, persistent viraemia and virologic failure.

CONCLUSION

In conclusion, these findings demonstrate that HIV-infected patients established on ART for more than six months in the African setting frequently experienced viraemia while continuing to be on ART. The findings also show that being on second line, low CD4 count, missing any day of ART and history of fever in the past week remain important predictors of virologic failure that should trigger intensified adherence counselling especially in the absence of reliable or readily available viral load monitoring. Finally, clinical care sites are different calling for further analyses to elucidate on the unique features of these sites.

A systematic review and cost-effectiveness analyses of the new World Health Organization guidelines for the treatment of HIV-positive adults in India

Background

The World Health Organization (WHO) in 2013 has revised its guidelines on antiretroviral therapy (ART) treatment for human immunodeficiency virus (HIV)-positive adults and further updated it in 2016. Based on the WHO recommendations, in May 2017, National AIDS Control Organisation, India recommended initiation of ART treatment for all people living with HIV, regardless of CD4 count, clinical stage, age, or population. This systematic review aims to assess the clinical effectiveness and cost implication of the new guidelines for India.

Methods

A systematic and comprehensive literature search on PubMed, OvidSP, Cochrane Library, and Google Scholar was carried out. Studies reporting either acquired immunodeficiency syndrome (AIDS) or mortality or both as outcome variables were selected. A meta-analysis of the available studies was carried out. The risk ratio was calculated to assess the reduction in AIDS or mortality or both. Cost-effectiveness analysis using health technology principles evaluating the lives saved in terms of incremental cost-effectiveness ratio and cost per quality-adjusted life years gained was carried out.

Results

Nine eligible studies were included for the meta-analysis. For India, the pooled relative risk of AIDS or mortality or both being 0.84 (95% confidence interval [CI], 0.76-0.92) and 0.78 (95% CI, 0.68-0.89) for ART initiation at CD4 count of ≤350 vs CD4 count of ≤500 and at CD4 count of ≤500 vs CD4 count > 500 cells/mm³, respectively. The incremental cost for per additional life saved is US$ 2592 and US$ 2357 for ART initiation at ≤500 and > 500 CD4 count, respectively.

Conclusion

The adoption of the new WHO guidelines is beneficial with substantial reduction in AIDS or mortality or both. This study suggests that adopting new WHO guidelines is cost-effective for India.

Duration of Human Immunodef iciency Virus Infection at Diagnosis among New Human Immunodef iciency Virus Cases in Dehong, Yunnan, China, 2008-2015

Background:

On diagnosis of human immunodeficiency virus (HIV) infection, a person may have been infected already for many years. This study aimed to estimate the duration of HIV infection at the time of diagnosis.

Methods:

Newly diagnosed HIV cases in Dehong, China, from 2008 to 2015 were studied. Duration of infection at the time of diagnosis was calculated using the first CD4 cell count result after diagnosis and a CD4 depletion model of disease progression. Multiple linear regression analysis was used to investigate the associated risk factors.

Results:

A total of 5867 new HIV cases were enrolled. Overall, mean duration of infection was 6.3 years (95% confidence interval [CI]: 6.2, 6.5). After adjusting for confounding, significantly shorter durations of infection were observed among participants who were female (beta: −0.37, 95% CI: −0.64, −0.09), Dai ethnicity (beta: −0.28, 95% CI: −0.57, 0.01), and infected through injecting drug use (beta: −1.82, 95% CI: −2.25, −1.39). Compared to the hospital setting, durations were shorter for those diagnosed in any other settings, and compared to 2008, durations were shorter for those diagnosed all years after 2010.

Results:

A total of 5867 new HIV cases were enrolled. Overall, mean duration of infection was 6.3 years (95% confidence interval [CI]: 6.2, 6.5). After adjusting for confounding, significantly shorter durations of infection were observed among participants who were female (beta: −0.37, 95% CI: −0.64, −0.09), Dai ethnicity (beta: −0.28, 95% CI: −0.57, 0.01), and infected through injecting drug use (beta: −1.82, 95% CI: −2.25, −1.39). Compared to the hospital setting, durations were shorter for those diagnosed in any other settings, and compared to 2008, durations were shorter for those diagnosed all years after 2010.

Conclusion:

Although the reduction in duration of infection at the time of diagnosis observed in Dehong was significant, it may not have had a meaningful impact.

The contribution of observational studies in supporting the WHO 'treat all' recommendation for HIV/AIDS

In 2015, the World Health Organization (WHO) recommended that all people living with HIV (PLWH) should start antiretroviral therapy (ART) irrespective of clinical or immune status. This recommendation followed almost 20 years of research into the clinical and population-level benefits and risks of starting ART early compared with deferring treatment. This article summarises the ways in which observational data support the work of WHO, including the support provided by the International epidemiology Databases to Evaluate AIDS (IeDEA), taking the example of 'treat all'.

Cardiac status of perinatally HIV-infected children: assessing combination antiretroviral regimens in observational studies

OBJECTIVE

To evaluate potential adverse associations of individual antiretroviral medications used in combination antiretroviral therapy regimens on cardiac structure and function in youth with perinatally-acquired HIV infection (PHIV).

DESIGN

PHIV youth (N = 325) enrolled in a prospective multisite cohort study had a single echocardiogram at age 7-16 years to evaluate cardiac function and structure.

METHODS

We applied several statistical approaches to evaluate associations between use of 18 individual antiretroviral medications with Z-scores for 11 measures of left ventricular function and structure. These included simultaneously evaluating all antiretroviral medications in adjusted linear regression models controlling for the false discovery rate (FDR), applying hierarchical models to estimate individual antiretroviral medication effects as deviations from drug class means, and evaluating latent measures of cardiac function and structure underlying multiple echocardiographic parameters.

RESULTS

Youth taking combination regimens with a protease inhibitor (69%) had significantly better cardiac function than those on other regimens. After FDR control and adjustment for other antiretroviral medications, no individual antiretroviral medication was significantly associated with any measure of left ventricular function, but zidovudine was associated with higher adjusted mean Z-scores for one measure of left ventricular structure (end-systolic wall stress). Factor analysis identified three latent factors: heart function, heart size, and heart wall stress. Lopinavir was associated with better heart function scores, whereas zidovudine was associated with higher wall stress scores. Zidovudine and nevirapine were associated with higher heart size factor scores.

CONCLUSIONS

Despite cardioprotective effects of combination regimens in PHIV youth, individual antiretroviral medications were associated with altered cardiac structure, which could progress to symptomatic cardiomyopathy in adulthood.

A review of time scale fundamentals in the g-formula and insidious selection bias

PURPOSE OF REVIEW

We review recent examples of data analysis with the g-formula, a powerful tool for analyzing longitudinal data and survival analysis. Specifically, we focus on the common choices of time scale and review inferential issues that may arise.

RECENT FINDINGS

Researchers are increasingly engaged with questions that require time scales subject to left-truncation and right-censoring. The assumptions necessary for allowing right-censoring are well defined in the literature, whereas similar assumptions for left-truncation are not well defined. Policy and biologic considerations sometimes dictate that observational data must be analyzed on time scales that are subject to left-truncation, such as age.

SUMMARY

Further consideration of left-truncation is needed, especially when biologic or policy considerations dictate that age is the relevant time scale of interest. Methodologic development is needed to reduce potential for bias when left-truncation may occur.

Long-term moderately elevated LDL-cholesterol and blood pressure and risk of coronary heart disease

Background

Harmful effects of long-term exposure to moderately elevated low-density lipoprotein (LDL)-cholesterol and blood pressure on coronary heart disease (CHD) have not been rigorously examined. We estimated the risk of CHD under long-term exposure to moderately elevated LDL-cholesterol and blood pressure compared with the risk under shorter exposures to higher levels of the same risk factors.

Methods

Observational study using data from 2,714 adults in Framingham Offspring Study who were free of existing cardiovascular disease and aged <70 years at baseline (1987–1991). We used the parametric g-formula to estimate 16-year CHD risk under different levels and durations of exposure to LDL-cholesterol (low: <130 mg/dL, moderate: 130 to <160 mg/dL, high 160 to <190 mg/dL, and very high: ≥190 mg/dL) and systolic blood pressure (low: <120 mmHg, prehypertension: 120 to <140 mmHg, stage 1 hypertension: 140 to <160 mmHg, and stage 2 hypertension: ≥160 mmHg).

Results

The estimated 16-year CHD risk under exposure to low LDL was 8.2% (95% CI = 7.0–9.6). The 16-year CHD risk under exposure to moderate LDL was 8.9% (7.8–10.1) which was similar to CHD risk under 8 years of low LDL followed by 8 years of high LDL at 9.0% (7.7–10.3); and 12 years of low LDL followed by 4 years of very high LDL at 8.8% (7.6–10.1). The results for blood pressure were similar.

Conclusions

Long-term exposure to moderate levels of LDL-cholesterol and blood pressure had a similar impact on CHD risk as shorter exposures to levels considered ‘high’ per clinical guidelines.

Optimal timing of antiretroviral treatment initiation in HIV-positive children and adolescents: a multiregional analysis from Southern Africa, West Africa and Europe

Background

There is limited knowledge about the optimal timing of antiretroviral treatment initiation in older children and adolescents.

Methods

A total of 20 576 antiretroviral treatment (ART)-naïve patients, aged 1-16 years at enrolment, from 19 cohorts in Europe, Southern Africa and West Africa, were included. We compared mortality and growth outcomes for different ART initiation criteria, aligned with previous and recent World Health Organization criteria, for 5 years of follow-up, adjusting for all measured baseline and time-dependent confounders using the g-formula.

Results

Median (1st;3rd percentile) CD4 count at baseline was 676 cells/mm 3 (394; 1037) (children aged ≥ 1 and < 5 years), 373 (172; 630) (≥ 5 and < 10 years) and 238 (88; 425) (≥ 10 and < 16 years). There was a general trend towards lower mortality and better growth with earlier treatment initiation. In children < 10 years old at enrolment, by 5 years of follow-up there was lower mortality and a higher mean height-for-age z-score with immediate ART initiation versus delaying until CD4 count < 350 cells/mm 3 (or CD4% < 15% or weight-for-age z-score < -2) with absolute differences in mortality and height-for-age z-score of 0.3% (95% confidence interval: 0.1%; 0.6%) and -0.08 (-0.09; -0.06) (≥ 1 and < 5 years), and 0.3% (0.04%; 0.5%) and -0.07 (-0.08; -0.05) (≥ 5 and < 10 years). In those aged > 10 years at enrolment we did not find any difference in mortality or growth with immediate ART initiation, with estimated differences of -0.1% (-0.2%; 0.6%) and -0.03 (-0.05; 0.00), respectively. Growth differences in children aged < 10 years persisted for treatment thresholds using higher CD4 values. Regular follow-up led to better height and mortality outcomes.

Conclusions

Immediate ART is associated with lower mortality and better growth for up to 5 years in children < 10 years old. Our results on adolescents were inconclusive.

From CD4-Based Initiation to Treating All HIV-Infected Adults Immediately: An Evidence-Based Meta-analysis

Background

The World Health Organization (WHO) Consolidated antiretroviral therapy (ART) guidelines set the CD4⁺ T-cell counts threshold to 500 cells/mm³ in 2013, and 2015 guidelines recommend treating all HIV-infected adults regardless of their CD4⁺ T-cell counts. To inform the decision-making around ART guidelines for people living with HIV, we systematically reviewed the literature to estimate differences in clinical benefits between individuals starting treatment with baseline CD4⁺ T-cell counts ≥500 cells/mm³ (early initiation) as compared to <500 cells/mm³ (deferred initiation).

Methods

We systematically searched the electronic databases and abstracts for randomized controlled trials (RCT) and observational studies. Outcomes were mortality, AIDS progression, AIDS or death, immunologic recovery, and virologic suppression. We pooled data across studies and performed analyses of effect sizes.

Results

We identified 13 studies comparing early and deferred treatment. The pooled risk ratio (RR) of mortality of 11 observational studies was 0.90 (95% CI 0.82–0.99), with moderate heterogeneity (I² = 53%). The pooled RR for progression to AIDS from two observational studies was 0.77 (95% CI 0.47–1.24). Five observational studies found a pooled RR of death or AIDS of 0.94 (95% CI 0.93–0.95). For the outcome of immunologic recovery, defined as CD4⁺ T-cell counts reaching at least 800 cells/mm³ after ART, one observational study found early initiation of ART had an HR (hazard ratio) of 2.39 (95% CI 1.93–2.96). The pooled RR of viral suppression (a viral load <50 copies/ml) after 9 months from one cohort was 1.04 (95% CI 0.99–1.09).

Conclusion

Mortality risk and risk for AIDS appear to be reduced among people living with HIV with early initiation of ART, based on current WHO guidelines, as compared to those with deferred initiation of ART (<500 cells/mm³).

Using Observational Data to Calibrate Simulation Models

BACKGROUND

Individual-level simulation models are valuable tools for comparing the impact of clinical or public health interventions on population health and cost outcomes over time. However, a key challenge is ensuring that outcome estimates correctly reflect real-world impacts. Calibration to targets obtained from randomized trials may be insufficient if trials do not exist for populations, time periods, or interventions of interest. Observational data can provide a wider range of calibration targets but requires methods to adjust for treatment-confounder feedback. We propose the use of the parametric g-formula to estimate calibration targets and present a case-study to demonstrate its application.

METHODS

We used the parametric g-formula applied to data from the HIV-CAUSAL Collaboration to estimate calibration targets for 7-y risks of AIDS and/or death (AIDS/death), as defined by the Center for Disease Control and Prevention under 3 treatment initiation strategies. We compared these targets to projections from the Cost-effectiveness of Preventing AIDS Complications (CEPAC) model for treatment-naïve individuals presenting to care in the following year ranges: 1996 to 1999, 2000 to 2002, or 2003 onwards.

RESULTS

The parametric g-formula estimated a decreased risk of AIDS/death over time and with earlier treatment. The uncalibrated CEPAC model successfully reproduced targets obtained via the g-formula for baseline 1996 to 1999, but over-estimated calibration targets in contemporary populations and failed to reproduce time trends in AIDS/death risk. Calibration to g-formula targets improved CEPAC model fit for contemporary populations.

CONCLUSION

Individual-level simulation models are developed based on best available information about disease processes in one or more populations of interest, but these processes can change over time or between populations. The parametric g-formula provides a method for using observational data to obtain valid calibration targets and enables updating of simulation model inputs when randomized trials are not available.

Effect of immediate initiation of antiretroviral treatment on the risk of acquired HIV drug resistance

OBJECTIVE

We estimated and compared the risk of clinically identified acquired drug resistance under immediate initiation [the currently recommended antiretroviral therapy (ART) initiation strategy], initiation with CD4 cell count less than 500 cells/μl and initiation with CD4 cell count less than 350 cells/μl.

DESIGN

Cohort study based on routinely collected data from the HIV-CAUSAL collaboration.

METHODS

For each individual, baseline was the earliest time when all eligibility criteria (ART-naive, AIDS free, and others) were met after 1999. Acquired drug resistance was defined using the Stanford classification as resistance to any antiretroviral drug that was clinically identified at least 6 months after ART initiation. We used the parametric g-formula to adjust for time-varying (CD4 cell count, HIV RNA, AIDS, ART regimen, and drug resistance testing) and baseline (calendar period, mode of acquisition, sex, age, geographical origin, ethnicity and cohort) characteristics.

RESULTS

In 50 981 eligible individuals, 10% had CD4 cell count more than 500 cells/μl at baseline, and 63% initiated ART during follow-up. Of 2672 tests for acquired drug resistance, 794 found resistance. The estimated 7-year risk (95% confidence interval) of acquired drug resistance was 3.2% (2.8,3.5) for immediate initiation, 3.1% (2.7,3.3) for initiation with CD4 cell count less than 500 cells/μl, and 2.8% (2.5,3.0) for initiation with CD4 cell count less than 350 cells/μl. In analyses restricted to individuals with baseline in 2005-2015, the corresponding estimates were 1.9% (1.8, 2.5), 1.9% (1.7, 2.4), and 1.8% (1.7, 2.2).

CONCLUSION

Our findings suggest that the risk of acquired drug resistance is very low, especially in recent calendar periods, and that immediate ART initiation only slightly increases the risk. It is unlikely that drug resistance will jeopardize the proven benefits of immediate ART initiation.

Effect of Immediate Initiation of Antiretroviral Treatment in HIV-Positive Individuals Aged 50 Years or Older

BACKGROUND

Clinical guidelines recommend immediate initiation of combined antiretroviral therapy for all HIV-positive individuals. However, those guidelines are based on trials of relatively young participants.

METHODS

We included HIV-positive antiretroviral therapy-naive, AIDS-free individuals aged 50-70 years after 2004 in the HIV-CAUSAL Collaboration. We used the parametric g-formula to estimate the 5-year risk of all-cause and non-AIDS mortality under (1) immediate initiation at baseline and initiation at CD4 count, (2) <500 cells/mm, and (3) <350 cells/mm. Results were presented separately for the general HIV population and for a US Veterans cohort with high mortality.

RESULTS

The study included 9596 individuals (28% US Veterans) with median (interquantile range) age of 55 (52-60) years and CD4 count of 336 (182-513) at baseline. The 5-year risk of all-cause mortality was 0.40% (95% confidence interval (CI): 0.10 to 0.71) lower for the general HIV population and 1.61% (95% CI: 0.79 to 2.67) lower for US Veterans when comparing immediate initiation vs initiation at CD4 <350 cells/mm. The 5-year risk of non-AIDS mortality was 0.17% (95% CI: -0.07 to 0.43) lower for the general HIV population and 1% (95% CI: 0.31 to 2.00) lower for US Veterans when comparing immediate initiation vs initiation at CD4 <350 cells/mm.

CONCLUSIONS

Immediate initiation seems to reduce all-cause and non-AIDS mortality in patients aged 50-70 years.

Comparing the Effectiveness of Dynamic Treatment Strategies Using Electronic Health Records: An Application of the Parametric g-Formula to Anemia Management Strategies

OBJECTIVE

To compare the effectiveness of dynamic anemia management strategies by applying the parametric g-formula to electronic health records.

DATA SOURCE/STUDY SETTING

Patients with end-stage renal disease from the US Renal Data System who had congestive heart failure or ischemic heart disease and were undergoing hemodialysis in outpatient dialysis facilities between 2006 and 2010.

STUDY DESIGN

We explicitly emulated a target trial of three ‎erythropoietin dosing strategies (aimed at achieving a low, middle, or high hematocrit) and estimated the observational analog of the per-protocol effect.

RESULTS

Of 156,945 eligible patients, 41,970 died during the 18-month follow-up. Compared to the low-hematocrit strategy, the estimated risk of death was 4.6 (95% CI 4.4-4.9) percentage points higher under the high-hematocrit strategy and 1.8 (95% CI 1.7-1.9) percentage points higher under the mid-hematocrit strategy. The corresponding risk differences for a composite outcome of death and myocardial infarction were similar.

CONCLUSION

An explicit emulation of a target trial using electronic health records, combined with the parametric g-formula, allowed comparison of real-world dynamic strategies that have not been compared in randomized trials.

CD4+ cells recovery in HIV positive patients with severe immunosuppression at HAART initiation at Centre Medico-Social Cor-Unum, Kigali

INTRODUCTION

Up to 30% of HIV infected patients who are receiving HAART do not exhibit a marked increase in the CD4+ T cell count. There is still a concern that immune recovery may not be complete once CD4+ T cells have decreased below 200 cells/μl. The objective is to assess CD4+ cell recovery in HIV+ patients with CD4 count below 200 cells/μl) at HAART initiation.

METHODS

This was a retrospective cohort study among 110 HIV+ patients with initial CD4 count < 200 cells/μl. Baseline Age, sex, CD4 count and viral load were extracted from the patient's database. After12 months of HAART; CD4 count was done using flow cytometry and viremia by COBAS AmpliPrep/COBAS TaqMan HIV-1 test v 2.0 technology.

RESULTS

The mean age of the respondents was 35 years; males being 57% and females were 43%. The mean CD4 count before HAART was 110.18 cells/μl whereas at 12 months of HAART; this was 305.01 cells/μl. Though some patients did not achieve a CD4 count of more than 200 cells/μl or a drop in viral load; there was a significant recovery of CD4+ cells (P value=0.000) and viremia following HAART (P value=0.001). Participants aged 18-30 years were likely to have less than 200 cells/μl CD4 count (46.4%) [OR=4.33; 95%CI: 1.29-14.59; P=0.018] than participants aged above 40 years (16.7%).

CONCLUSION

HAART was associated with viremia suppression but many patients failed to achieve a CD4 count >200 cells/μl. HAART before severe immunosuppression is a key factor for immune restoration among HIV+ patients.

Immediate Antiretroviral Therapy Reduces Risk of Infection-Related Cancer During Early HIV Infection

BACKGROUND

 In the Strategic Timing of Antiretroviral Treatment (START) study, immediate combination antiretroviral therapy (cART) initiation reduced cancer risk by 64%. We hypothesized that risk reduction was higher for infection-related cancer and determined by differences in CD4 cell counts and human immunodeficiency virus (HIV) RNA between the study arms.

METHODS

 Incident malignancies in START were categorized into infection-related and infection-unrelated cancer. We used Cox models to assess factors associated with both cancer categories. We used sequential adjustment for baseline covariates, cancer risk factors, and HIV-specific variables to investigate potential mediators of cancer risk reduction with immediate cART.

RESULTS

 There were 14 cancers among persons randomized to immediate cART (6 infection-related and 8 infection-unrelated) and 39 cancers in the deferred arm (23 infection-related and 16 infection-unrelated); hazard ratios of immediate vs deferred cART initiation were 0.26 (95% confidence interval [CI], .11-.64) for infection-related and 0.49 (95% CI, .21-1.15) for infection-unrelated cancer. Independent predictors of infection-related cancer were older age, higher body mass index, low- to middle-income region, HIV RNA, and baseline CD8 cell count. Older age and baseline CD8 cell count were independent predictors of infection-unrelated cancer. Adjustment for latest HIV RNA level had little impact on the protective effect of immediate cART on infection-related cancer. Adjustment for latest HIV RNA level, but not for CD4 cell count or cancer risk factors, attenuated the effect of immediate cART on infection-unrelated cancer.

CONCLUSIONS

 Immediate cART initiation significantly reduces risk of cancer. Although limited by small sample size, this benefit does not appear to be solely attributable to HIV RNA suppression and may be also mediated by other mechanisms.

Initiation of Antiretroviral Therapy in Early Asymptomatic HIV Infection

BACKGROUND

Data from randomized trials are lacking on the benefits and risks of initiating antiretroviral therapy in patients with asymptomatic human immunodeficiency virus (HIV) infection who have a CD4+ count of more than 350 cells per cubic millimeter.

METHODS

We randomly assigned HIV-positive adults who had a CD4+ count of more than 500 cells per cubic millimeter to start antiretroviral therapy immediately (immediate-initiation group) or to defer it until the CD4+ count decreased to 350 cells per cubic millimeter or until the development of the acquired immunodeficiency syndrome (AIDS) or another condition that dictated the use of antiretroviral therapy (deferred-initiation group). The primary composite end point was any serious AIDS-related event, serious non-AIDS-related event, or death from any cause.

RESULTS

A total of 4685 patients were followed for a mean of 3.0 years. At study entry, the median HIV viral load was 12,759 copies per milliliter, and the median CD4+ count was 651 cells per cubic millimeter. On May 15, 2015, on the basis of an interim analysis, the data and safety monitoring board determined that the study question had been answered and recommended that patients in the deferred-initiation group be offered antiretroviral therapy. The primary end point occurred in 42 patients in the immediate-initiation group (1.8%; 0.60 events per 100 person-years), as compared with 96 patients in the deferred-initiation group (4.1%; 1.38 events per 100 person-years), for a hazard ratio of 0.43 (95% confidence interval [CI], 0.30 to 0.62; P<0.001). Hazard ratios for serious AIDS-related and serious non-AIDS-related events were 0.28 (95% CI, 0.15 to 0.50; P<0.001) and 0.61 (95% CI, 0.38 to 0.97; P=0.04), respectively. More than two thirds of the primary end points (68%) occurred in patients with a CD4+ count of more than 500 cells per cubic millimeter. The risks of a grade 4 event were similar in the two groups, as were the risks of unscheduled hospital admissions.

CONCLUSIONS

The initiation of antiretroviral therapy in HIV-positive adults with a CD4+ count of more than 500 cells per cubic millimeter provided net benefits over starting such therapy in patients after the CD4+ count had declined to 350 cells per cubic millimeter. (Funded by the National Institute of Allergy and Infectious Diseases and others; START ClinicalTrials.gov number, NCT00867048.).