New England Journal of Medicine AUGUST 27, 2015

Initiation of Antiretroviral Therapy in Early Asymptomatic HIV Infection

The INSIGHT START Study Group

Bottom Line

The START trial definitively demonstrated that initiating antiretroviral therapy in asymptomatic HIV-positive adults with preserved CD4+ counts (>500 cells/mm³) significantly reduces the risk of serious AIDS-related and non-AIDS-related events compared to deferring therapy.

Key Findings

1. The primary composite endpoint of serious AIDS-related events, serious non-AIDS-related events, or death occurred in 1.8% (42 patients, 0.60 events per 100 person-years) of the early-treatment group versus 4.1% (96 patients, 1.38 events per 100 person-years) of the deferred-treatment group (HR, 0.43; 95% CI, 0.30 to 0.62; P<0.001) [9.1.1].

2. Serious AIDS-related events were significantly reduced, occurring in 14 patients in the early-treatment group compared to 50 in the deferred-treatment group (HR, 0.28; 95% CI, 0.15 to 0.50; P<0.001).

3. Serious non-AIDS-related events were also reduced with early therapy, occurring in 29 patients in the early-treatment group and 47 in the deferred-treatment group (HR, 0.61; 95% CI, 0.38 to 0.97; P=0.04).

Study Design

Design

RCT

Open-Label

Sample

4,685

Patients

Duration

3.0 yr

Median

Setting

Multicenter, 35 countries

Population HIV-positive, antiretroviral-naive adults with a CD4+ count greater than 500 cells/mm³

Intervention Early initiation of combination antiretroviral therapy (ART) immediately after randomization

Comparator Deferred initiation of ART until the CD4+ count declined to <350 cells/mm³ or a clinical AIDS-defining event developed

Outcome A composite of a serious AIDS-related event, a serious non-AIDS-related event, or death from any cause

Study Limitations

• The trial utilized an open-label design, which could potentially introduce ascertainment or reporting bias, although the primary clinical endpoints were objective and adjudicated by a blinded endpoint review committee [9.1.1].

• Because the study was halted early for efficacy after a median follow-up of 3.0 years, the ability to fully evaluate long-term cumulative toxicities and resistance profiles of early, lifelong ART was somewhat limited.

• The overall event rate was lower than originally projected during study design, reflecting the generally benign short-term natural history of early asymptomatic HIV infection with high CD4+ counts.

Clinical Significance

The START trial settled one of the longest-standing debates in HIV medicine by proving the unequivocal clinical benefit of universal treatment. Its findings provided the definitive evidence required by global health organizations (including the WHO and DHHS) to universally adopt 'treat all' guidelines, recommending ART for all HIV-infected individuals regardless of CD4+ cell count.

Historical Context

For decades, the optimal time to initiate ART was heavily debated due to concerns over early drug toxicity, resistance, and financial cost. While trials like HPTN 052 previously proved that early ART prevented the sexual transmission of HIV, the direct clinical benefit to the asymptomatic patient with preserved immunity (CD4 >500) remained theoretically uncertain until START provided definitive proof.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

How does uncontrolled HIV viremia, even in early asymptomatic stages with preserved CD4+ counts (>500 cells/mm3), contribute to non-AIDS-related complications such as cardiovascular disease and malignancies, which the START trial found were reduced by early antiretroviral therapy (ART)?

Key Response

This tests foundational pathophysiology by linking chronic viral replication to persistent systemic inflammation, immune activation, and endothelial dysfunction, explaining why HIV harms the body even before classical immunosuppression (AIDS) occurs.

Resident

A newly diagnosed, asymptomatic HIV patient with a CD4 count of 650 cells/mm3 is hesitant to start ART, citing concerns about pill fatigue and potential side effects since they 'feel fine.' Based on the findings of the START trial, how do you counsel them regarding the balance of clinical risks and benefits?

Key Response

Residents must apply clinical trial data directly to patient counseling. The rationale relies on START's definitive finding that early ART significantly reduces both serious AIDS-related events and non-AIDS-related events (like cardiovascular disease, renal disease, and non-AIDS malignancies), demonstrating that the risk of untreated chronic infection far outweighs the risks of modern ART toxicity.

Fellow

The START trial highlighted a significant reduction in non-AIDS-defining events with immediate ART. Immunologically, how does early intervention impact the CD4/CD8 ratio and markers of T-cell exhaustion (e.g., PD-1 expression), and why are these specific parameters critical prognostic indicators for non-AIDS comorbidities?

Key Response

Challenges infectious disease fellows to connect macroscopic trial outcomes to advanced immunologic concepts. Early ART prevents the inversion of the CD4/CD8 ratio and mitigates chronic T-cell activation/exhaustion, which are independent drivers of accelerated aging and end-organ damage in people living with HIV.

Attending

Prior to the START trial, the 'deferral' strategy was largely driven by historical concerns over cumulative drug toxicity and viral resistance. How do we teach trainees to balance the traditional medical paradigm of 'primum non nocere' with the modern realization that in HIV, the untreated virus is inherently more toxic than the treatment?

Key Response

Encourages reflective teaching and wisdom. Historically, older ART regimens (e.g., AZT, d4T) were highly toxic, making delayed treatment logical. The START trial marked a paradigm shift, proving that with safer modern integrase inhibitors, the chronic inflammation of the virus itself is the true 'toxin', fundamentally altering our risk-benefit calculus.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The START trial was halted early by the Data and Safety Monitoring Board (DSMB) due to overwhelming efficacy. How does early trial cessation for benefit potentially inflate the estimated treatment effect size (the 'winner's curse'), and what statistical adjustments should be employed to project accurate long-term population impacts?

Key Response

Explores a critical methodological phenomenon where early stopping rules can exaggerate treatment effects due to random high fluctuations at the time of interim analysis, which is vital for researchers designing subsequent longitudinal models or cost-effectiveness analyses.

Journal Editor

Considering the START trial's open-label design, how might differential ascertainment bias or changes in health-seeking behavior between the immediate and deferred groups have influenced the reporting of subjective or non-fatal secondary endpoints, and how adequately did the authors mitigate this?

Key Response

Focuses on rigorous critical appraisal. An editor would scrutinize whether patients aware they were not receiving therapy (deferred group) might report symptoms differently or seek medical care at different thresholds, potentially skewing the rates of non-fatal clinical events.

Guideline Committee

The START trial provided the definitive Level I evidence that prompted the DHHS and WHO to recommend universal ART for all HIV-infected individuals regardless of CD4 count. From a guideline perspective, how do we reconcile this universal 'treat all' recommendation with the practical challenges of resource allocation, supply chain security, and adherence support in resource-limited global settings?

Key Response

Connects trial evidence to guideline evolution. While the START trial provided the biological and clinical justification for treating everyone (shifting guidelines from CD4 <350 or <500 to 'all'), guideline committees must also address implementation science, acknowledging that a Grade 1A recommendation requires immense health systems infrastructure to execute globally without exacerbating disparities.

Clinical Landscape

Noteworthy Related Trials

2006

SMART Trial

n = 5,472 · NEJM

Tested

Continuous antiretroviral therapy for viral suppression

Population

HIV-infected adults with CD4 count > 350

Comparator

Episodic ART (drug conservation) guided by CD4 count drops

Endpoint

Opportunistic disease or death from any cause

Key result: Episodic therapy significantly increased the risk of opportunistic disease or death compared to continuous therapy.

2011

HPTN 052

n = 1,763 · NEJM

Tested

Early initiation of ART (CD4 350-550)

Population

HIV-discordant couples

Comparator

Delayed ART (CD4 < 250 or AIDS-defining illness)

Endpoint

Linked HIV transmission to negative partner and HIV-related clinical events

Key result: Early ART reduced the risk of linked sexual transmission of HIV by 96% and decreased HIV-related clinical events.

2015

TEMPRANO ANRS 12136

n = 2,056 · NEJM

Tested

Early antiretroviral therapy (ART) and 6 months of isoniazid preventive therapy

Population

HIV-infected adults in resource-limited settings with high CD4 counts

Comparator

Deferred ART based on WHO criteria and no IPT

Endpoint

Severe HIV morbidity or all-cause mortality

Key result: Early ART and IPT independently reduced the risk of severe HIV-related illness or death compared to deferred therapy.

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