Prognostic factors of combined viral load and CD4+ cell count responses under triple antiretroviral therapy, Aquitaine cohort, 1996-1998

Factors associated with immunological and virological discordant responses to highly active antiretroviral therapy among adult HIV positive individuals in Ethiopia: A cross-sectional study

In clinical practice, not all human immune deficiency virus (HIV) positive individuals who received highly active antiretroviral therapy (HAART) achieve the desired concordant response characterized by a sustained viral suppression or immune recovery. The expected success of HAART doesn't occur in all treated patients and a discordant response between CD4 count and the viral load (VL) has been a major concern in the treatment of HIV patients. Thus, this study is designed to describe the factors associated with immunological and virological discordant responses to HAART among adult HIV positive individuals.A hospital-based cross-sectional study with secondary data review was conducted on 423 HIV positive individuals on HAART from February 1 to April 30, 2017. Socio-demographic characteristics, clinical data and about 10 mL of blood specimen for HIV VL, and CD4 count measurement were collected. The data was entered into SPSS version 20 and descriptive, bivariate, and multivariate logistic regression analysis was employed.The mean age of the patients at study time was 39 (±9.8). The average follow-up duration of patients on antiretroviral therapy (ART) was 7 (±3) years. The prevalence of immunological discordance and virological discordance to HAART were 13.2% and 47%, respectively. With multivariate logistic regression analysis duration of follow-up on ART ≤ 6 years (adjusted odds ratio [AOR] = 3.29 (1.80-6.03), P ≤ .001) and VL ≥20 copies/mm3 (AOR = 3.08 [1.70-5.61], P ≤ .001) were significant factors for immunological discordance conversely the patients who switched drug as a result of TB (AOR = 3.33 [1.10-10.08], P = .03) was significant factors for virological discordance.The prevalence of immunological discordance and virological discordance to HAART among HIV patients is high. Patients with the duration of follow-up on ART ≤ 6 years, VL ≥ 20 copies/mm3 and patients who switched drugs as a result of TB were significant factors for discordance. Hence, intensive adherence support and counseling should be provided to achieve the UNAIDS 90 target. HIV positive individuals co-infected with TB, who have had VL ≥ 20 copies/mm3 and who are ≤6 years duration of follow-up on ART need to be carefully monitored. In addition, national based study of discordant groups is recommended.

[Factors associated with immunovirologic dissociation in HIV-1-infected patients under highly active antiretroviral therapy in the Ambulatory Treatment Center (ATC) in Dakar]

INTRODUCTION

The objective of this work is to evaluate the different factors associated with immunovirologic dissociation despite highly active and effective antiretroviral treatment.

METHODS

We conducted a retrospective, cohort, descriptive and analytical study of the medical records of HIV-1 infected patients having received at least 12 months of antiretroviral therapy, followed in the ATC cohort from 2001 to 2011 and with undetectable viral load in the last 6 months.

RESULTS

During this 10-year study period, the prevalence of IVD was 19.3%. Female sex was predominant, with a sex ratio of 1.9. Immunovirologic dissociation was more frequent in male patients (29.7% vs 14.1%) with a statistically significant difference (p = 0,00006). The average age was 44 years ± 10 years. A history of tuberculosis was found in about a third of the cases (31.4%). Immunovirologic dissociation was significantly more frequent in patients with a history of tuberculosis (p = 0.00005). Most patients (68%) had AIDS at WHO clinical stages 3 or 4. Patients with immunovirologic dissociation were more often in WHO clinical stages 3 and 4 (p = 0.0001). More than half of the cases (56.2%) were found to be malnourished and immunovirologic dissociation was prevalent in malnourished patients (p=0.005). The mean CD4+ T lymphocytes counts was 86.7± 83 cells / mm3. Immunovirologic dissociation was more frequent in patients with initial low CD4+ T lymphocyte counts and with a statistically significant difference (p = 0.00000). By multivariate analysis, only age greater than or equal to 43 years, CD4 initial counts < 100 c/mm3 and male sex were significantly associated with this immunovirologic dissociation.

CONCLUSION

Our study assessed the main factors associated with immunovirologic dissociation. Other studies of this nature would also merit consideration in order to highlight the impact of this partial immune response on the emergence of opportunistic infections or the implementation of a specific tritherapy for the sole purpose of producing fully successful immune restoration.

Risk of Severe Non AIDS Events Is Increased among Patients Unable to Increase their CD4+ T-Cell Counts >200+/μl Despite Effective HAART

Background

Immunological non-response (INR) despite virological suppression is associated with AIDS-defining events/death (ADE). Little is known about its association with serious non-AIDS-defining events (nADE).

Methods

Patients highly-active antiretroviral therapy (HAART) with <200 CD4+/μl and achieving HIV-RNA <50 copies/ml within 12 (±3) months were categorized as INR if CD4+ T-cell count at year 1 was <200/μl. Predictors of nADE (malignancies, severe infections, renal failure—ie, estimated glomerular filtration rate <30 ml/min, cardiovascular events and liver decompensation) were assessed using multivariable Cox models. Follow-up was right-censored in case of HAART discontinuation or confirmed HIV-RNA>50.

Results

1221 patients were observed for a median of 3 (IQR: 1.3-6.1) years. Pre-HAART CD4+ were 77/μl (IQR: 28-142) and 56% of patients had experienced an ADE. After 1 year, CD4+ increased to 286 (IQR: 197-387), but 26.1% of patients were INR. Thereafter, 86 nADE (30.2% malignancies, 27.9% infectious, 17.4% renal, 17.4% cardiovascular, 7% hepatic) were observed, accounting for an incidence of 1.83 events (95%CI: 1.73-2.61) per 100 PYFU. After adjusting for measurable confounders, INR had a significantly greater risk of nADE (HR 1.65; 95%CI: 1.06-2.56). Older age (per year, HR 1.03; 95%CI: 1.01-1.05), hepatitis C co-infection (HR 2.09; 95%CI: 1.19-3.7), a history of previous nADE (HR 2.16; 95%CI: 1.06-4.4) and the occurrence of ADE during the follow-up (HR 2.2; 95%CI: 1.15-4.21) were other independent predictors of newly diagnosed nADE.

Conclusions

Patients failing to restore CD4+ to >200 cells/μl run a greater risk of serious nADE, which is intertwined or predicted by AIDS progression. Improved management of this fragile population and innovative therapy able to induce immune-reconstitution are urgently needed. Also, our results strengthen the importance of earlier diagnosis and HAART introduction.

Poor CD4 recovery and risk of subsequent progression to AIDS or death despite viral suppression in a South African cohort

INTRODUCTION

The prognostic role of CD4 response in the first six months of treatment in patients achieving early viral suppression during HIV treatment is unclear.

METHODS

This was a cohort study of HIV-positive adults initiating antiretroviral therapy (ART) between April 2004 and August 2007 who achieved viral suppression (<400 copies/ml) by six months on treatment in South Africa. Immunological response at six months was defined as: (1) absolute CD4 reached (<200 vs. ≥ 200 cells/ml); (2) absolute CD4 reached (0-49, 50-200 and ≥ 200 cells/ml); and (3) CD4 increase from ART initiation (<0, 0-49, 50-199 and ≥ 200 cells/ml). We used Cox regression models to determine the relationship between each definition and both new AIDS-defining condition and death.

RESULTS

A total of 4129 patients were eligible for analysis; 212 (5.1%) of those patients experienced a new AIDS-defining condition and 154 (3.7%) died. Smaller CD4 gains by six months were associated with higher hazards of progression to AIDS (CD4<50 vs. ≥ 200 cells/ml; adjusted hazard ratio (aHR): 2.6; 95% CI: 1.2-2.1) and death (aHR: 2.8; 95% CI: 1.4-5.7). A decrease in CD4 count since ART initiation through six months (aHR: 2.4; 95% CI: 1.2-4.9) and smaller CD4 count gains (0-49 cells/ml; aHR: 2.0; 95% CI: 1.2-3.4 and 50-199 cells/ml; aHR: 1.5; 95% CI: 0.9-2.2) were also associated with greater risk of progression to AIDS compared to an increase of ≥ 200 cells/ml. When we examined mortality differences by gender among this virally suppressed cohort, a higher proportion of males died compared to females, 4.7% versus 3.2%, p=0.01. However, in multivariable analysis, we did not observe any significant differences: aHR: 1.39; 95% CI: 0.98-1.95.

CONCLUSIONS

Patients on ART with poor CD4 recovery early in treatment are at greater risk of progression to new AIDS diagnosis or death despite viral suppression. Approaches to managing this sub-group of patients need further investigation.

Virologic and immunologic outcome of HAART in Human Immunodeficiency Virus (HIV)-1 infected patients with and without tuberculosis (TB) and latent TB infection (LTBI) in Addis Ababa, Ethiopia

BACKGROUND

HIV/TB coinfection remains a major challenge even after the initiation of HAART. Little is known about Mycobacterium tuberculosis (Mtb) specific immune restoration in relation to immunologic and virologic outcomes after long-term HAART during co-infections with latent and active TB.

METHODS

A total of 232 adults, including 59 HIV patients with clinical TB (HIV + TB+), 125 HIV patients without clinical TB (HIV + TB-), 13 HIV negative active TB patients (HIV-TB+), and 10 HIV negative Tuberculin Skin TST positive (HIV-TST+), and 25 HIV-TST- individuals were recruited. HAART was initiated in 113 HIV + patients (28 TB + and 85 TB-), and anti-TB treatment for all TB cases. CD4+ T-cell count, HIV RNA load, and IFN-γ responses to ESAT-6/CFP-10 were measured at baseline, 6 months (M6), 18 months (M18) and 24 months (M24) after HAART initiation.

RESULTS

The majority of HIV + TB- (70%, 81%, 84%) as well as HIV + TB + patients (60%, 77%, 80%) had virologic success (HIV RNA < 50 copies/ml) by M6, M18 and M24, respectively. HAART also significantly increased CD4+ T-cell counts at 2 years in HIV + TB + (from 110.3 to 289.9 cells/μl), HIV + TB- patients (197.8 to 332.3 cells/μl), HIV + TST- (199 to 347 cells/μl) and HIV + TST + individuals (195 to 319 cells/μl). Overall, there was no significant difference in the percentage of patients that achieved virologic success and in total CD4+ counts increased between HIV patients with and without TB or LTBI. The Mtb specific IFN-γ response at baseline was significantly lower in HIV + TB + (3.6 pg/ml) compared to HIV-TB + patients (34.4 pg/ml) and HIV + TST + (46.3 pg/ml) individuals; and in HIV-TB + patients compared to HIV-TST + individuals (491.2 pg/ml). By M18 on HAART, the IFN-γ response remained impaired in HIV + TB + patients (18.1 pg/ml) while it normalized in HIV + TST + individuals (from 46.3 to 414.2 pg/ml).

CONCLUSIONS

Our data show that clinical and latent TB infections do not influence virologic and immunologic outcomes of ART in HIV patients. Despite this, HAART was unable to restore optimal TB responsiveness as measured by Mtb specific IFN-γ response in HIV/TB patients. Improvement of Mtb-specific immune restoration should be the focus of future therapeutic strategies.

Effect of age on immunological response in the first year of antiretroviral therapy in HIV-1-infected adults in West Africa

OBJECTIVE

To assess the effect of aging on the immunological response to antiretroviral therapy (ART) in the West African context.

METHODS

The change in CD4 T-cell count was analysed according to age at the time of ART initiation among HIV-infected patients enrolled in the International epidemiological Database to Evaluate AIDS (IeDEA) Collaboration in the West African region. CD4 gain over 12 months of ART was estimated using linear mixed models. Models were adjusted for baseline CD4 cell count, sex, baseline clinical stage, calendar period and ART regimen.

RESULTS

The total number of patients included was 24,107, contributing for 50,893 measures of CD4 cell count in the first year of ART. The baseline median CD4 cell count was 144 cells/μl [interquartile range (IQR) 61-235]; median CD4 cell count reached 310 cells/μl (IQR 204-443) after 1 year of ART. The median age at treatment initiation was 36.3 years (10th-90th percentiles = 26.5-50.1). In adjusted analysis, the mean CD4 gain was significantly higher in younger patients (P < 0.0001). At 12 months, patients below 30 years recovered an additional 22 cells/μl on average [95% confidence interval (CI) 2-43] compared to patients at least 50 years.

CONCLUSION

Among HIV-infected adults in West Africa, the immunological response after 12 months of ART was significantly poorer in elderly patients. As the population of treated patients is likely to get older, the impact of this age effect on immunological response to ART may increase over time.

Sub-optimal CD4 T-lymphocyte responses among HIV infected patients who develop TB during the first year of ART

STUDY BACKGROUND: Poor CD4 T-lymphocyte responses to anti-retroviral treatment (ART) are associated with increased HIV disease progression and mortality. In sub-Saharan Africa a substantial proportion of HIV infected patients are co-infected with TB. This study evaluated the effect of active TB presenting after ART initiation on immunological responses to ART. METHODS: A retrospective cohort study was conducted of patients initiated on ART in a South African academic hospital between 1 January 2004 and 15 May 2008. Changes in CD4 T-lymphocyte count, virological suppression and incident TB episodes occurring in the first year of ART were assessed. Sub-optimal CD4 responses were defined as 'failure to increase CD4 T-lymphocyte count by 50cells/μl at 6 month on ART'. RESULTS: The cohort for analysis included 691 patients. 141 (20.4%) had sub-optimal CD4 responses at 6 months on ART. 49 patients (7.1%) developed incident TB within the first 12 months of ART. After adjustment for age, sex, baseline CD4 count and detectable viral load, patients with incident TB were found to have a 2.20 times greater odds of a sub-optimal CD4 response at 6 month of ART as compared to those who were TB free (95%CI: 1.14-4.23). CONCLUSION: Incident TB was associated with a poor CD4 response during early ART in this cohort. Although the direction of causality cannot be determined from these data, these findings provide additional support for the initiation of ART at higher CD4 counts.

Immunological failure despite virological suppression in HIV seropositive individuals on antiretroviral therapy

BACKGROUND

Some individuals experience a discordant response during antiretroviral therapy (ART), with a blunted CD4+ cell count response despite low HIV-1 RNA plasma levels.

MATERIALS AND METHODS

CD4 counts and viral load of 251 individuals on ART referred to the center were analysed for immunological failure. The viral load tests of 28 patients revealed a discordant response, characterized by low CD4 counts despite viral suppression (<47 copies in 23, <5000 in 4 patients and <10000 in one patient). Univariate and multiple regression analysis was done to determine factors associated with immunological failure in patients with viral suppression.

RESULTS

Twenty-eight patients developed immunological failure over a duration of 3.7±1.14 years despite viral suppression. In univariate analysis of discordant patients, low CD4 counts(<100cells/μl) at start of ART(P=0.0261), less than 50% gain in CD4 count (P=0.048) after one year of start of ART and duration on ART for more than 3 years (P=0.0436) were associated with immunological failure. In multiple regression, duration on ART, age and nadir CD4 count (lowest ever) on treatment were predictors of immunological failure in these patients. Overall females (n=8) demonstrated much higher CD4 counts of 136±72 than males (n=20) 79±38 cells/μl at the time of diagnosis of immunological failure.

CONCLUSIONS

Discordance was observed in 13.59% of patients. Detection of failure to first line therapy based on immunologic criteria, without viral load testing, can result in unnecessary switches to 2(nd) line therapy.

Factors associated with paradoxical immune response to antiretroviral therapy in HIV infected patients: a case control study

Background

A paradoxical immunologic response (PIR) to Highly Active Antiretroviral Therapy (HAART), defined as viral suppression without CD4 cell-count improvement, has been reported in the literature as 8 to 42%, around 15% in most instances. The present study aims to determine, in a cohort of HIV infected patients in Brazil, what factors were independently associated with such a discordant response to HAART.

Methods

A case-control study (1:4) matched by gender was conducted among 934 HIV infected patients on HAART in Brazil. Cases: patients with PIR, defined as CD4 < 350 cells/mm³ (hazard ratio for AIDS or death of at least 8.5) and undetectable HIV viral load on HAART for at least one year. Controls: similar to cases, but with CD4 counts ≥ 350 cells/mm³. Eligibility criteria were applied. Data were collected from medical records using a standardized form. Variables were introduced in a hierarchical logistic regression model if a p-value < 0.1 was determined in a bivariate analysis.

Results

Among 934 patients, 39 cases and 160 controls were consecutively selected. Factors associated with PIR in the logistic regression model were: total time in use of HAART (OR 0.981; CI 95%: 0.96-0.99), nadir CD4-count (OR 0.985; CI 95%: 0.97-0.99), and time of undetectable HIV viral load (OR 0.969; CI 95%: 0.94-0.99).

Conclusions

PIR seems to be related to a delay in the management of immunodeficient patients, as shown by its negative association with nadir CD4-count. Strategies should be implemented to avoid such a delay and improve the adherence to HAART as a way to implement concordant responses.

Effect of baseline CD4 cell counts on the clinical significance of short-term immunologic response to antiretroviral therapy in individuals with virologic suppression

BACKGROUND

Achieving virologic suppression is a clear therapeutic goal for patients receiving combination antiretroviral therapy (cART). However, the effects of immunologic responses, whether measured as CD4 count changes from baseline or CD4 counts at follow-up, in patients with virologic suppression, have not been clearly established.

METHODS

Treatment-naive individuals aged > or =16 years, who initiated cART between 1998 and 2005 in participating cohorts of the ART Cohort Collaboration and achieved viral load < or =400 copies per milliliter 6 months after cART initiation, were included. We used Cox models to examine associations of CD4 change from baseline to 6 months, and absolute CD4 counts at 6 months, with subsequent rates of mortality and AIDS. Analyses were stratified by baseline CD4 count.

RESULTS

Among 23,679 eligible participants, the median increase in CD4 count at 6 months, and the implications of these increases for subsequent mortality and AIDS, varied with baseline CD4 count. Mortality hazard ratios for increases of 0-50 cells per microliter, compared with >100 cells per microliter, were 1.87 (95% confidence interval: 1.28 to 2.73), 1.60 (1.13 to 2.28), 0.98 (0.58 to 1.65) and 1.24 (0.70 to 2.18) in participants with baseline CD4 cell count <50, 50-199, 200-349 and > or =350 cells per microliter, respectively. In contrast, hazard ratios for mortality or AIDS associated with absolute CD4 cell counts at 6 months were similar across all but the highest baseline CD4 cell count strata.

CONCLUSION

It is not possible to derive thresholds for change in CD4 count that define an adequate immunologic response in individuals receiving cART. Absolute CD4 counts at 6 months are a more useful measure of immunologic response and subsequent prognosis.

CD4 responses in the setting or suboptimal virological responses to antiretroviral therapy: features, outcomes, and associated factors

The factors associated with discordant viroimmunological responses following antiretroviral therapy are unclear. We studied 1380 patients who initiated a protease inhibitor (PI)-based antiretroviral regimen and who fulfilled the criteria for inclusion. Of them, 255 (18.5%) had CD4 increases > or =100 cells/microl after 1 year of therapy despite detectable viral load (immunological responders); they were compared with 669 patients (48.5%) who had CD4 increases <100 cells/microl regardless of their final viral load (immunological nonresponders). Immunological responders had higher rates of sexual acquisition of HIV (p = 0.03), lower rates of clinical progression (p = 0.02), higher probabilities of being naive to antiretroviral therapy (p = 0.006) or to PI if antiretroviral experienced (p = 0.03), higher rates of receiving only nucleoside reverse transcriptase inhibitors in addition to the PI (p = 0.04), and lower baseline CD4 counts (p = 0.007) and higher viral loads (p = 0.009), as compared with nonresponders. Multivariate analysis revealed that sexual transmission of HIV (homosexual p = 0.004, heterosexual p = 0.03), no prior PI experience (p = 0.005), absence of clinical progression (p = 0.02), and lower baseline CD4 counts (p = 0.03) were independently associated with immunological response. However, these factors differed according to the patients' prior antiretroviral status, as higher baseline viral load was also associated with immunological response in antiretroviral-experienced patients (p = 0.02), whereas baseline CD4 count (p = 0.007) was the only predictive parameter in antiretroviral-naive patients. We conclude that immunological responses despite suboptimal viral suppression are common. Prior PI experience, HIV transmission category, baseline CD4 counts, and clinical progression were independently predictive of this condition, although the associated factors were different depending on the patient's prior antiretroviral history.

Factors associated with poor immunologic responses despite viral suppression in markedly immunosuppressed patients

To determine the factors associated with poor immunologic responses despite viral suppression in markedly immunocompromised patients (</=200 CD4 cells per microliter at baseline), individuals with less than 100 CD4 increases after 12 months of nelfinavir-based highly active antiretroviral therapy (HAART; n = 114) were compared to those with 100 or more CD4 increases (n = 338). Responders were more likely to be naïve to antiretroviral therapy (p = 0.009) and to protease inhibitors (p< 0.001), less likely to have undetectable viral load at baseline (p = 0.01), to be infected through injection drug use (p = 0.02), to receive two versus three daily nelfinavir doses (p = 0.05), and to have higher viral load (p< 0.001) and lower CD4 counts (p = 0.03) at baseline than nonresponders. Logistic regression analysis revealed that baseline viral load (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.64-0.91), two daily nelfinavir doses (OR 1.85, 95% CI 1.12-3.03) and prior treatment with protease inhibitors (OR 1.85, 95% CI 1.11-3.07) were significantly predictive of poor immunologic responses. On the contrary, viral load had no predictive role in antiretroviral therapy (ART)-naïve patients (p = 0.7). We conclude that poor immunologic responses are common in these patients. Lower viral load at baseline is associated with poorer responses, which could be related to suboptimal prior antiretroviral therapy. In patients taking nelfinavir, administration in two versus three daily doses is also associated with worse immunologic responses.

Clinical outcome of HIV-infected patients with sustained virologic response to antiretroviral therapy: long-term follow-up of a multicenter cohort

Background

Limited information exists on long-term prognosis of patients with sustained virologic response to antiretroviral therapy. We aimed to assess predictors of unfavorable clinical outcome in patients who maintain viral suppression with HAART.

Methods

Using data collected from ten clinic-based cohorts in Spain, we selected all antiretroviral-naive adults who initiated HAART and maintained plasma HIV-1 RNA levels <500 copies/mL throughout follow-up. Factors associated with disease progression were determined by Cox proportional-hazards models.

Results

Of 2,613 patients who started HAART, 757 fulfilled the inclusion criteria. 61% of them initiated a protease inhibitor-based HAART regimen, 29.7% a nonnucleoside reverse-transcriptase inhibitor-based regimen, and 7.8% a triple-nucleoside regimen. During 2,556 person-years of follow-up, 22 (2.9%) patients died (mortality rate 0.86 per 100 person-years), and 40 (5.3%) died or developed a new AIDS-defining event. The most common causes of death were neoplasias and liver failure. Mortality was independently associated with a CD4-T cell response <50 cells/L after 12 months of HAART (adjusted hazard ratio [AHR], 4.26 [95% confidence interval {CI}, 1.68–10.83]; P = .002), and age at initiation of HAART (AHR, 1.06 per year; 95% CI, 1.02–1.09; P = .001). Initial antiretroviral regimen chosen was not associated with different risk of clinical progression.

Conclusions

Patients with sustained virologic response on HAART have a low mortality rate over time. Long-term outcome of these patients is driven by immunologic response at the end of the first year of therapy and age at the time of HAART initiation, but not by the initial antiretroviral regimen selected.

Application and impact of population pharmacokinetics in the assessment of antiretroviral pharmacotherapy

Population pharmacokinetics has been an important technique used to explore and define relevant sources of variation in drug exposure and response in patient populations. This has been especially true in the area of antiretroviral therapy where the assurance of adequate and sustained drug exposure of multiple agents is highly correlated with therapeutic success. Population pharmacokinetic analyses across the four drug classes and 20 US FDA-approved products used to treat HIV have been published to date. The published reports were predominantly based on actual clinical trials conducted in HIV-infected patients with one or more agents administered. Modelling and simulation approaches have been used in the evaluation of antiretroviral agent outcomes incorporating problematic design and analysis factors such as sparse plasma sampling, data imbalance and censored data. Additional benefits of population modelling approaches applied to the investigation of antiretroviral agents include the ability to assess dosing compliance, understanding and quantifying drug-drug interactions in order to select dosing regimens and the screening of new drug candidates. Pharmacokinetic/pharmacodynamic models have been used to characterise the relationship between drug exposure and virological and immunological response, and to predict clinical outcome. These models offer the best opportunity for individualising and optimising patient therapy, particularly when adjusted for adherence/compliance. The impact of population pharmacokinetics in the area of antiretroviral therapy can be directly assessed by its role in the validation of surrogate markers such as viral RNA load, therapeutic drug monitoring and the management of individual patient outcomes via exposure-toxicity relationships. Each of these population pharmacokinetic outcomes has contributed to the current regulatory environment, specifically in the area of accelerated approval of new antiretroviral agents.

Response to highly active antiretroviral therapy varies with age: the UK and Ireland Collaborative HIV Paediatric Study

OBJECTIVE

To evaluate the effect of age, CD4 percentage (CD4%) and plasma HIV-1 RNA on response to highly active antiretroviral therapy (HAART) in previously untreated children.

DESIGN

Cohort study.

METHODS

We examined the association between age at HAART initiation, and CD4 and HIV-1 RNA response using logistic and Cox regression, adjusting for sex, route of infection and pre-HAART values.

RESULTS

CD4% increases of > 10% at 6 months were more likely in younger children [odds ratio (OR), 0.84 per year, P < 0.001] and those with lower pre-HAART CD4% (OR, 0.67 per 5% higher, P < 0.001), but were not related to pre-HAART HIV-1 RNA (P = 0.6). In contrast, HIV-1 RNA suppression < 400 copies/ml at 6 months was more likely in older children (OR, 1.09 per year, P = 0.03), and was unrelated to pre-HAART HIV-1 RNA or CD4% (P > 0.3). CD4% was still increasing during the second year following HAART initiation (60% followed > 24 months). Longer-term increases in CD4% occurred faster, and decreases in HIV-1 RNA occurred more slowly in younger children. The median time to CD4% >/= 30% after initiating HAART with CD4% </= 25% was under 12 months for children under 2 years irrespective of pre-HAART CD4%, and increased progressively in older children and as CD4% decreased.

CONCLUSIONS

Children respond immunologically to HAART irrespective of pre-HAART HIV-1 RNA or clinical status. However, immunological response is better in younger children and those with lowest CD4%, whereas younger children have poorer virological response, increasing the risk of resistance. Differences in response to HAART according to age and underlying risk of disease progression should be considered when initiating HAART in children.

Virological rebound after suppression on highly active antiretroviral therapy

OBJECTIVE To determine the rate of virological rebound and factors associated with rebound among patients on highly active antiretroviral therapy (HAART) with previously undetectable levels of viraemia. DESIGN An observational cohort study of 2444 patients from the EuroSIDA study. METHODS Patients were followed from their first viral load under 400 copies/ml to the first of two consecutive viral loads above 400 copies/ml. Incidence rates were calculated using person-years of follow-up (PYFU), Cox proportional hazards models were used to determine factors related to rebound. RESULTS Of 2444 patients, 1031 experienced virological rebound (42.2%). The incidence of rebound decreased over time; from 33.5 in the first 6 months after initial suppression to 8.6 per 100 PYFU at 2 years after initial suppression (P < 0.0001). The rate of rebound was lower for treatment-naive compared with treatment-experienced patients. In multivariate models, patients who changed treatment were more likely to rebound, as were patients with higher viral loads on starting HAART. Treatment-naive patients were less likely to rebound. Among pretreated patients, those who were started on new nucleosides were less likely to rebound. CONCLUSION The rate of virological rebound decreased over time, suggesting that the greatest risk of treatment failure is in the months after initial suppression. Treatment-naive patients were at a lower risk of rebound, but among drug-experienced patients, those who added new nucleosides had a lower risk of rebound, as were patients with a good immunological response.

Immunological recovery despite virological failure is independent of human immunodeficiency virus-type 1 resistant mutants in children receiving highly active antiretroviral therapy

Relationships between human immunodeficiency virus-type-1 (HIV-1) drug-resistant mutants and immunological recovery were investigated after 12-week antiretroviral therapy in 43 children infected perinatally with virological failure. Twenty-two children received highly active antiretroviral therapy (HAART) and 21 received double therapy with reverse transcriptase inhibitors. At baseline, no difference in reverse transcriptase or protease inhibitors resistant mutants was present among the groups. After 12 weeks, the two groups were similar regarding proportion of children with reverse transcriptase resistant mutants. Sixteen (73%) HAART-treated children, but no child receiving double therapy had HIV-1 with primary resistance mutations to protease inhibitors. Secondary protease mutations were found in all HAART-treated and in 17/21 (81%) children receiving double therapy. The mutation numbers in reverse transcriptase or protease genes were significantly higher after HAART than after double therapy. Nevertheless, 12 (55%) of HAART-treated children (but no child receiving double therapy) showed immunological recovery. The frequency and number of mutations were similar in HAART-treated children with or without immunological recovery both at baseline and after 12 weeks. The findings suggest, immunological recovery notwithstanding, virological failure is independent of drug-resistant mutations and consequent possible changes in viral fitness.

Virologic and Immunologic Response to Highly Active Antiretroviral Therapy

Highly active antiretroviral therapy (HAART) delays clinical progression to AIDS by suppressing viral replication, allowing the immune system to reconstitute. These virologic and immunologic consequences do not occur uniformly among HAART users; markers of HIV disease stage at the time of HAART initiation are critical determinants of the progression while under HAART. In this paper, we review studies describing the heterogeneous virologic and immunologic progression following the initiation of HAART, and update findings obtained in the Multicenter AIDS Cohort Study that show that CD4 cell count and history of antiretroviral therapy at the time of initiation are independent determinants of response.