Clinical progression rates by CD4 cell category before and after the initiation of combination antiretroviral therapy (cART)

Understanding the HIV Epidemic Among MSM in Baltimore: A Modeling Study Estimating the Impact of Past HIV Interventions and Who Acquired and Contributed to Infections

Supplemental Digital Content is Available in the Text.

Men who have sex with men (MSM) in the United States are disproportionately affected by HIV. We estimated the impact of past interventions and contribution of different population groups to incident MSM HIV infections.

Long-term evolution of CD4+ cell count in patients under combined antiretroviral therapy

OBJECTIVE

Combined antiretroviral treatment (cART) results in profound immunologic improvement, but it is unclear whether CD4 cell counts return to levels similar to those of HIV-negative individuals. We explore long-term CD4 cell count evolution post-cART and its association with baseline levels, virologic suppression, pre-cART cumulative viremia and other factors.

DESIGN

Data were derived from the AMACS. Included individuals were adults who started cART, at least 2003, while previously ART-naive.

METHODS

Changes in CD4 cell counts were modeled through piecewise linear mixed models.

RESULTS

A total of 3405 individuals were included. The majority was male (86.0%), homosexual (58.8%) with median (IQR) age at cART initiation 36 (31-44) years and a median (IQR) follow-up of 3.9 (2.0-6.9) years. Most persons (57%) starting cART with less than 200 cells/μl did not reach 600 cells/μl after 7 years of treatment. Those starting cART with 200-349 CD4 cells/μl could reach 600 cells/μl within less than 2 years of fully suppressive treatment. Probability of CD4 normalization (i.e. >800 cells/μl) after 7 years of suppressive treatment was 24 and 46% for those starting treatment with less than 200 or 200-349 CD4 cells/μl, respectively. Lower pre-cART cumulative viremia was associated with faster CD4 recovery. CD4 cell count increases after 4 years were either insignificant or very slow, irrespectively of baseline levels.

CONCLUSION

cART initiation before CD4 cell count drops below 350 cells/μl is crucial for achieving normal CD4 levels. These findings underline the importance of timely diagnosis and cART initiation as the risk of both AIDS and non-AIDS-related morbidity/mortality remains increased in patients with incomplete CD4 recovery.

Incidence of AIDS-Defining Opportunistic Infections in a Multicohort Analysis of HIV-infected Persons in the United States and Canada, 2000-2010

BACKGROUND

There are few recent data on the rates of AIDS-defining opportunistic infections (OIs) among human immunodeficiency virus (HIV)-infected patients in care in the United States and Canada.

METHODS

We studied HIV-infected participants in 16 cohorts in the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) during 2000-2010. After excluding 16 737 (21%) with any AIDS-defining clinical events documented before NA-ACCORD enrollment, we analyzed incident OIs among the remaining 63 541 persons, most of whom received antiretroviral therapy during the observation. We calculated incidence rates per 100 person-years of observation (hereafter, "person-years") with 95% confidence intervals (CIs) for the first occurrence of any OI and select individual OIs during 2000-2003, 2004-2007, and 2008-2010.

RESULTS

A total of 63 541 persons contributed 261 573 person-years, of whom 5836 (9%) developed at least 1 OI. The incidence rate of any first OI decreased over the 3 observation periods, with 3.0 cases, 2.4 cases, and 1.5 cases per 100 person-years of observation during 2000-2003, 2004-2007, and 2008-2010, respectively (Ptrend<.001); the rates of most individual OIs decreased as well. During 2008-2010, the leading OIs included Pneumocystis jiroveci pneumonia, esophageal candidiasis, and disseminated Mycobacterium avium complex or Mycobacterium kansasii infection.

CONCLUSIONS

For HIV-infected persons in care during 2000-2010, rates of first OI were relatively low and generally declined over this time.

How many people are living with undiagnosed HIV infection? An estimate for Italy, based on surveillance data

Objective:

To estimate the size and characteristics of the undiagnosed HIV population in Italy in 2012 applying a method that does not require surveillance data from the beginning of the HIV epidemic.

Methods:

We adapted the method known as ‘London method 2’; the undiagnosed population is estimated as the ratio between the estimated annual number of simultaneous HIV/clinical AIDS diagnoses and the expected annual progression rate to clinical AIDS in the undiagnosed HIV population; the latter is estimated using the CD4⁺ cell count distribution of asymptomatic patients reported to surveillance. Under-reporting/ascertainment of new diagnoses was also considered. Also, the total number of people living with HIV was estimated.

Results:

The undiagnosed HIV population in 2012 was 13 729 (95% confidence interval: 12 152–15 592), 15 102 (13 366–17 151) and 16 475 (14 581–18 710), assuming no under-reporting/ascertainment, 10 and 20% of under-reporting/ascertainment, respectively. The percentage of undiagnosed cases was higher among HIV people aged below 25 years (25–28%), MSM (16–19%) and people born abroad (16–19%), whereas it was small among injection drug users (3%).

Conclusion:

The estimate of people in Italy with undiagnosed HIV in 2012 was in a plausible range of 12 000–18 000 cases, corresponding to 11–13% of the overall prevalence. The method is straightforward to implement only requiring annual information from the HIV surveillance system about CD4⁺ cell count and clinical stage at HIV diagnosis. Thus, it could be used to monitor if a certain prevention initiative lead to the reduction of the undiagnosed HIV population over time. It can also be easily implemented in other countries collecting the same basic information from the HIV surveillance system.

CD4 testing at clinics to assess eligibility for antiretroviral therapy

BACKGROUND

In 2011, the Ministry of Health raised the CD4 threshold for antiretroviral therapy (ART) eligibility from <250 cells/µl and <350 cells/µl, but at the same time only 8.8% of facilities in Malawi with HIV services provided CD4 testing. We conducted a record review at 10 rural clinics in Thyolo District to assess the impact of introducing CD4 testing on identifying patients eligible for ART.

METHODS

We abstracted CD4 counts of all ART-naïve, HIV-infected patients with WHO clinical stages 1 and 2 and an initial CD4 test between May 2008 and June 2009. At four clinics, we also abstracted CD4 counts of patients not initially eligible for ART who were retested before April 2010.

RESULTS

Of 1,113 patients tested, the initial CD4 was "≤250 cells/µl" and "≤350 cells/µl" in 534 (48.0%). Of 203 patients with follow-up results, the most recent CD4 was ≤250 cells/µl in 34 (24.5%), and ≤350 cells/µl in 64 (46.0%).

CONCLUSIONS

CD4 testing in rural clinics is feasible and identifies many patients eligible for ART who would not be identified without CD4 testing. CD4 testing needs to be scaled-up to identify patients eligible for ART. ART services need to be scaled-up concurrently to meet the resulting increased demand.

Considerations in the rationale, design and methods of the Strategic Timing of AntiRetroviral Treatment (START) study

BACKGROUND

Untreated human immunodeficiency virus (HIV) infection is characterized by progressive depletion of CD4+ T lymphocyte (CD4) count leading to the development of opportunistic diseases (acquired immunodeficiency syndrome (AIDS)), and more recent data suggest that HIV is also associated with an increased risk of serious non-AIDS (SNA) diseases including cardiovascular, renal, and liver diseases and non-AIDS-defining cancers. Although combination antiretroviral treatment (ART) has resulted in a substantial decrease in morbidity and mortality in persons with HIV infection, viral eradication is not feasible with currently available drugs. The optimal time to start ART for asymptomatic HIV infection is controversial and remains one of the key unanswered questions in the clinical management of HIV-infected individuals.

PURPOSE

In this article, we outline the rationale and methods of the Strategic Timing of AntiRetroviral Treatment (START) study, an ongoing multicenter international trial designed to assess the risks and benefits of initiating ART earlier than is currently practiced. We also describe some of the challenges encountered in the design and implementation of the study and how these challenges were addressed.

METHODS

A total of 4000 study participants who are HIV type 1 (HIV-1) infected, ART naïve with CD4 count > 500 cells/µL are to be randomly allocated in a 1:1 ratio to start ART immediately (early ART) or defer treatment until CD4 count is <350 cells/µL (deferred ART) and followed for a minimum of 3 years. The primary outcome is time to AIDS, SNA, or death. The study had a pilot phase to establish feasibility of accrual, which was set as the enrollment of at least 900 participants in the first year.

RESULTS

Challenges encountered in the design and implementation of the study included the limited amount of data on the risk of a major component of the primary endpoint (SNA) in the study population, changes in treatment guidelines when the pilot phase was well underway, and the complexities of conducting the trial in a geographically wide population with diverse regulatory requirements. With the successful completion of the pilot phase, more than 1000 participants from 100 sites in 23 countries have been enrolled. The study will expand to include 237 sites in 36 countries to reach the target accrual of 4000 participants.

CONCLUSIONS

START is addressing one of the most important questions in the clinical management of ART. The randomization provided a platform for the conduct of several substudies aimed at increasing our understanding of HIV disease and the effects of antiretroviral therapy beyond the primary question of the trial. The lessons learned from its design and implementation will hopefully be of use to future publicly funded international trials.

Disease-modifying therapeutic concepts for HIV in the era of highly active antiretroviral therapy

Chronic HIV infection is associated with persistent immune activation and inflammation even among patients virologically suppressed on antiretroviral therapy for years. Chronic immune activation has been associated with poor outcomes--both AIDS-defining and non-AIDS-defining clinical events--and persistent CD4 T-cell depletion. The cause of chronic immune activation in well-controlled HIV infection is unknown. Proposed drivers include residual viral replication, microbial translocation, and coinfecting pathogens. Therapeutic interventions targeting immune activation are emerging, from approaches that interfere directly with activation and inflammatory pathways to those that prevent microbial translocation or decrease the availability of host target cells for the virus. In the context of the disappointing results of the interleukin-2 trials, the main challenges to developing these disease-modifying therapies include identifying an adequate target population and choosing surrogate endpoints that will provide positive proof-of-concept that the interventions will translate into long-term clinical benefit before embarking on large clinical endpoint trials.

CD4 cell responses to combination antiretroviral therapy in patients starting therapy at high CD4 cell counts

OBJECTIVE

To examine CD4 cell responses to combination antiretroviral therapy (cART) in patients enrolled in the Australian HIV Observational Database who commenced cART at CD4 cell counts >350 cells per microliter.

METHODS

CD4 cell counts were modelled using random effects, repeated measurement models in 432 HIV-infected adults from Australian HIV Observational Database who commenced their first cART regimen and had a baseline CD4 count >350 cells per microliter. Using published AIDS and/or death incidence rates combined with the data summarized by time and predicted CD4 cell count, we calculated the expected reduction in risk of an event for different starting baseline CD4 strata.

RESULTS

Mean CD4 counts increased above 500 cells per microliter in all baseline CD4 strata by 12 months (means of 596, 717, and 881 cells/μL in baseline CD4 strata 351-500, 501-650, and >650 cells/μL, respectively) and after 72 months since initiating cART, mean CD4 cell counts (by increasing baseline CD4 strata) were 689, 746, 742 cells per microliter. The expected reduction in risk of mortality for baseline CD4 counts >650 cells per microliter relative to 351-500 cells per microliter was approximately 8%, an absolute risk reduction 0.33 per 1000 treated patient-years.

CONCLUSIONS

Patients starting cART at high CD4 cell counts (>650 cells/μL) tend to maintain this immunological level over 6 years of follow-up. Patients starting from 351 to 500 CD4 cells per microliter achieve levels of >650 cells per microliter after approximately 3 years of cART. Initiating cART with a baseline CD4 count 501-650 or >650 cells per microliter relative to 351-500 cells per microliter indicated a minimal reduction in risk of AIDS incidence and/or death.

Long-term increase in CD4+ T-cell counts during combination antiretroviral therapy for HIV-1 infection

OBJECTIVE

To inform guidelines concerning when to initiate combination antiretroviral therapy (ART), we investigated whether CD4(+) T-cell counts (CD4 cell counts) continue to increase over long periods of time on ART. Losses-to-follow-up and some patients discontinuing ART at higher CD4 cell counts hamper such evaluation, but novel statistical methods can help address these issues. We estimated the long-term CD4 cell count trajectory accounting for losses-to-follow-up and treatment discontinuations.

DESIGN

The study population included 898 US patients first initiating ART in a randomized trial (AIDS Clinical Trials Group 384); 575 were subsequently prospectively followed in an observational study (AIDS Clinical Trials Group Longitudinal Linked Randomized Trials).

METHODS

Inverse probability of censoring weighting statistical methods were used to estimate the CD4 cell count trajectory accounting for losses-to-follow-up and ART discontinuations, overall and for pretreatment CD4 cell count categories (<or=200, 201-350, 351-500, and >500 cells/microl).

RESULTS

Median CD4 cell count increased from 270 cells/microl pre-ART to an estimated 556 cells/microl at 3 and 532 cells/microl at 7 years after starting ART in analyses ignoring treatment discontinuations, and to 570 and 640 cells/microl, respectively, had all patients continued ART. However, even had ART been continued, an estimated 25, 9, 3, and 2% of patients with pretreatment CD4 cell counts of 200 or less, 201-350, 351-500, and more than 500 cells/microl would have had CD4 cell counts of 350 cells/microl or less after 7 years.

CONCLUSION

If patients remain on ART, CD4 cell counts increase in most patients for at least 7 years. However, the substantial percentage of patients starting therapy at low CD4 cell counts who still had low CD4 cell counts after 7 years provides support for ART initiation at higher CD4 cell counts.

Interleukin-2 therapy in patients with HIV infection

BACKGROUND

Used in combination with antiretroviral therapy, subcutaneous recombinant interleukin-2 raises CD4+ cell counts more than does antiretroviral therapy alone. The clinical implication of these increases is not known.

METHODS

We conducted two trials: the Subcutaneous Recombinant, Human Interleukin-2 in HIV-Infected Patients with Low CD4+ Counts under Active Antiretroviral Therapy (SILCAAT) study and the Evaluation of Subcutaneous Proleukin in a Randomized International Trial (ESPRIT). In each, patients infected with the human immunodeficiency virus (HIV) who had CD4+ cell counts of either 50 to 299 per cubic millimeter (SILCAAT) or 300 or more per cubic millimeter (ESPRIT) were randomly assigned to receive interleukin-2 plus antiretroviral therapy or antiretroviral therapy alone. The interleukin-2 regimen consisted of cycles of 5 consecutive days each, administered at 8-week intervals. The SILCAAT study involved six cycles and a dose of 4.5 million IU of interleukin-2 twice daily; ESPRIT involved three cycles and a dose of 7.5 million IU twice daily. Additional cycles were recommended to maintain the CD4+ cell count above predefined target levels. The primary end point of both studies was opportunistic disease or death from any cause.

RESULTS

In the SILCAAT study, 1695 patients (849 receiving interleukin-2 plus antiretroviral therapy and 846 receiving antiretroviral therapy alone) who had a median CD4+ cell count of 202 cells per cubic millimeter were enrolled; in ESPRIT, 4111 patients (2071 receiving interleukin-2 plus antiretroviral therapy and 2040 receiving antiretroviral therapy alone) who had a median CD4+ cell count of 457 cells per cubic millimeter were enrolled. Over a median follow-up period of 7 to 8 years, the CD4+ cell count was higher in the interleukin-2 group than in the group receiving antiretroviral therapy alone--by 53 and 159 cells per cubic millimeter, on average, in the SILCAAT study and ESPRIT, respectively. Hazard ratios for opportunistic disease or death from any cause with interleukin-2 plus antiretroviral therapy (vs. antiretroviral therapy alone) were 0.91 (95% confidence interval [CI], 0.70 to 1.18; P=0.47) in the SILCAAT study and 0.94 (95% CI, 0.75 to 1.16; P=0.55) in ESPRIT. The hazard ratios for death from any cause and for grade 4 clinical events were 1.06 (P=0.73) and 1.10 (P=0.35), respectively, in the SILCAAT study and 0.90 (P=0.42) and 1.23 (P=0.003), respectively, in ESPRIT.

CONCLUSIONS

Despite a substantial and sustained increase in the CD4+ cell count, as compared with antiretroviral therapy alone, interleukin-2 plus antiretroviral therapy yielded no clinical benefit in either study. (ClinicalTrials.gov numbers, NCT00004978 [ESPRIT] and NCT00013611 [SILCAAT study].)