Virologic and immunologic response to highly active antiretroviral therapy

Highly active antiretroviral therapy (HAART) delays clinical progression by suppressing viral replication, measured by a substantial reduction in HIV RNA, allowing the immune system to reconstitute, measured in most studies by an increase in CD4 cells. 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 receiving HAART. In this report, we review studies describing the heterogeneous virologic and immunologic progression after the initiation of HAART, discuss methodologic concerns in the study of the response of biomarkers, and update findings obtained in the Multicenter AIDS Cohort Study, which show that CD4 cell count, history of antiretroviral therapy, and age at the time of initiation are independent determinants of response.     

Virologic and immunologic response,clinical progression,and highly active antiretroviral therapy adherence

A growing body of evidence suggests that a high degree of adherence is required to achieve and maintain a successful virologic response both in the short and long term. This holds true despite the definition of adherence or how it is measured. Reported differences in the degree of adherence required are likely due to differences in study design, difficulty measuring patient adherence, patient population studied, and the antiretroviral regimen studied. Virologic suppression and immunologic response often go hand in hand, but the impact of adherence on change in CD4 count tends to be delayed and, therefore, less apparent than the impact on HIV viral load. Degree of adherence has also been shown to be associated with AIDS-related morbidity, mortality, and hospitalizations.     

Virologic and immunologic response to highly active antiretroviral therapy in indigenous and nonindigenous HIV-1-infected patients in the Netherlands

OBJECTIVE: To compare the results of antiretroviral treatment (highly active antiretroviral therapy [HAART]) in indigenous Dutch (ID) and nonindigenous HIV-1-infected patients in Amsterdam, the Netherlands. We focused on the largest groups of nonindigenous people visiting our outpatient clinic: patients from other industrialized countries (western), from Surinam/Netherlands Antilles (SNA), and from sub-Saharan Africa (SSA). DESIGN: Retrospective cohort analysis of 692 therapy-naive HIV-1-positive individuals who visited our outpatient clinic for the first time between July 1, 1996 and December 31, 2001. METHODS: We compared the groups at the time of their first visit to our clinic; at the start of HAART; and according to the virological, immunologic, and clinical treatment response during the 96 weeks after the start of HAART. RESULTS: Of the patients starting antiretroviral therapy, 362 were ID, 84 were western, 72 were from SNA, and 110 were from SSA. SNA and SSA patients had a lower CD4 cell count at first visit (ID = 330 cells/mm(3), western = 330 cells/mm(3), SNA = 250 cells/mm(3), and SSA = 170 cells/mm(3); P = 0.0002). Treatment in SNA and SSA patients was also started at a lower CD4 cell count, but the plasma HIV-1 RNA level was comparable. After the start of HAART, a similar rise in CD4 cell count was seen in the 4 groups (P = 0.33), but the baseline difference in CD4 cell count remained present during the follow-up period of 96 weeks. After adjusting for variables potentially influencing treatment outcome, the proportion of patients not reaching a plasma HIV-1 RNA level <400 copies/mL was not different for the 4 groups in contrast to the percentage not reaching a plasma HIV-1 RNA level <50 copies/mL (at 48 weeks: ID = 4.8%, western = 27.5%, SNA = 23.1%, and SSA = 24.2%; P = 0.017 over the 96-week time period). After the start of HAART, nonindigenous patients also more often had progression to Centers for Disease Control and Prevention (CDC) stage C or died (P = 0.006). CONCLUSIONS: In nonindigenous patients, treatment with HAART was equally successful in terms of the increase in CD4 cell count but was substantially less effective in achieving a plasma HIV-1 RNA level below 50 copies/mL. Further investigations should explore differences in adherence and pharmacokinetics in these patient groups.     

Dissociation of immunologic and virologic responses to highly active antiretroviral therapy

OBJECTIVE: Immunologic markers, levels of HIV DNA, and infectious HIV were compared in partial responders (PR) to HAART who had high plasma HIV RNA levels but stable or increasing levels of CD4+ peripheral blood mononuclear cells (PBMC), and patients with complete failure (CF) who had very low or decreasing levels of CD4+ PBMC and high plasma HIV RNA levels. DESIGN AND METHODS: CD4 and CD8 levels were monitored by flow cytometry. Beta2-microglobulin (beta2M) and neopterin levels were measured by quantitative enzyme immunoassays. Plasma and PBMC from 11 PR and 13 CF were analyzed for infectious HIV levels in limiting dilution cultures. Polymerase chain reaction (PCR) assays were used to quantify cellular HIV DNA and plasma HIV RNA. RESULTS: In comparison with CF, PR had little or no CD4+ cell loss, a substantial increase in CD8+ cells, significantly fewer positive plasma HIV cultures (p = .03), lower frequencies of infectious HIV in total PBMC (p = .005) and in CD4+ PBMC (p < .001), and lower frequencies of HIV DNA in CD4+ PBMC (p = .007). CONCLUSIONS: Lower levels of infectious HIV and a lower frequency of CD4+ PBMC that contain "productive" HIV DNA in PR as compared with CF may contribute to the stable or increasing CD4+ PBMC levels of the PR. However, HAART may also have effects on lymphocyte homeostasis independent of its antiviral activity.     

Chinese pediatric highly active antiretroviral therapy observational cohort: a 1-year analysis of clinical, immunologic, and virologic outcomes

BACKGROUND: Few data are available on the outcomes of pediatric antiretroviral therapy (ART) in the developing world. METHODS: Eighty-three children were followed prospectively in China from July 2005 to August 2006 and received (zidovudine or stavudine) plus lamivudine plus (nevirapine or efavirenz). RESULTS: Fifty-one children were ART naive at enrollment, and 32 were ART experienced. After 12 months, median weight increased by 0.3 weight for age z-score, median CD4 count increased from 116 to 340 cells/mm (P < 0.0001), and median viral load decreased from 5.53 to <2.60 log10 copies/mL (P < 0.0001) in the previously ART-naive children. In the ART-experienced children, median CD4 count increased from 193 to 318 cells/mm (P = 0.13), despite little change in median viral load (4.85 to 4.58 log10 copies/mL; P = 0.83). The viral load was <400 copies/mL in 55% of the previously ART-naive children and in 16% of the ART-experienced children. CONCLUSIONS: Weight and CD4 cell counts improved, and more than half of previously ART-naive patients had undetectable viral loads at 1 year. Future efforts should focus on improved virologic suppression through improved adherence and access to second-line regimens.     

Discordant immunologic and virologic responses to highly active antiretroviral therapy are associated with increased mortality and poor adherence to therapy

OBJECTIVE: To examine the independent association of discordant virologic and immunologic responses to highly active antiretroviral therapy (HAART) with mortality. METHODS: A population-based study of 1527 treatment-naive individuals initiating HAART used Cox proportional hazards modeling to determine the independent association of treatment response at 3 to 9 months with nonaccidental mortality. Logistic regression was used to examine associations with discordant responses. RESULTS: Viral load (VL)/CD4 discordant responses were seen in 235 (15.4%) of subjects, and VL/CD4 responses were seen in 179 (11.7%) of subjects. In adjusted Cox regression models, discordant responses were found to be independently associated with an increased risk of mortality (VL/CD4: relative hazard [RH] = 1.87, 95% confidence interval [CI]: 1.15 to 3.04; VL/CD4: RH = 2.47, 95% CI: 1.54 to 3.95). VL/CD4 discordance was found to be associated with increasing age, baseline HIV RNA load <100,000 copies/mL, baseline CD4 counts <50 cells/muL, the use of lamivudine (3TC)/zidovudine (ZDV), and poor adherence to therapy. VL/CD4 discordance was associated with younger age; injection drug use; baseline HIV RNA load >100,000 copies/mL; the use of 3TC/ZDV, didanosine (ddI)/3TC, or ddI/stavudine; and poor adherence to therapy. CONCLUSION: Discordant responses are independently associated with an increased risk of mortality and are, in turn, associated with poor adherence to therapy.     

Reliability of CD4 quantitation in human immunodeficiency virus-positive children: implications for definition of immunologic response to highly active antiretroviral therapy

Our objective was to develop data-based algorithms for definition of immunologic response to AIDS therapies in pediatric patients, taking account of T-cell subset measurement errors. The study design involved cross-protocol analysis of 2,148 enrollees in six completed Pediatric AIDS Clinical Trials Group trials. We used standard quantitation of T-cell subsets; linear modeling with mean-dependent measurement error variance was used to develop 95% tolerance limits for change in CD4%. For individuals with a CD4% of approximately 25%, the measurement error-based 95% tolerance interval ranges from 15% to 35%, whereas for individuals with a CD4% of approximately 5%, the tolerance interval ranges from 3% to 7%. When pairs of CD4% measures taken within a time interval of less than 30 days are averaged to estimate steady-state CD4%, tolerance interval width decreases by approximately 30%. A simple graphical tool that provides a data-based criterion for immunologic response over and above variation ascribable to T-cell measurement error is provided. Variability in CD4% due to measurement error is substantial, increases with level of CD4%, and complicates assessment of immunologic response to therapy. Replicates of CD4% measures could be used to improve precision of interpretation of CD4% measures.     

Clinical outcome of HIV-infected antiretroviral-naive patients with discordant immunologic and virologic responses to highly active antiretroviral therapy

BACKGROUND: The prognostic significance of a response to highly active antiretroviral therapy (HAART) that is immunologically and virologically discordant is not well understood. METHODS: Four hundred four antiretroviral-naive patients initiating HAART at an urban HIV outpatient clinic in 1995 to 2004 were analyzed. The association of treatment responses at 3 to 9 months after HAART initiation with time to development of an opportunistic infection (OI) or death was determined using Cox proportional hazards modeling. Logistic regression modeling was used to examine the association between discordant responses and patient characteristics. RESULTS: Of 404 patients, 70.5% experienced favorable concordant responses (CD4 cell count [CD4]+/viral load [VL]+: increase in CD4 count of >or=50 cells/microL and achievement of undetectable plasma HIV RNA level), 15.8% an immunologic response only (CD4+/VL(-)), 8.7% a virologic response only (CD4(-)/VL+), and 5.0% a concordant unfavorable response (CD4(-)/VL(-)). Both types of discordant responses (CD4+/VL(-) and CD4(-)/VL+), nonresponse (CD4(-)/VL(-)), and baseline CD4 cell count were significantly associated with earlier development of an OI or death (relative hazard [RH] = 2.81, 95% confidence interval [CI]: 1.31 to 3.97; RH = 4.83, 95% CI: 2.10 to 11.12; and RH = 0.93, 95% CI: 0.88 to 0.99, respectively). CD4+/VL(-) and CD4(-)/VL(-) were associated with nonwhite race in multivariate logistic regression models (adjusted OR = 2.83, 95% CI: 1.46 to 5.47 and adjusted OR = 6.50, 95% CI: 1.65 to 25.69, respectively). CONCLUSION: Discordant immunologic and virologic responses at 3 to 9 months after HAART initiation play important roles in predicting long-term clinical outcomes in treatment-naive patients.     

Comparison of clinical response to initial highly active antiretroviral therapy in the patients in clinical care in the United States and Brazil

BACKGROUND: US and Brazilian studies indicate that highly active antiretroviral therapy (HAART) has been effective in reducing morbidity and mortality from HIV/AIDS. Differences exist in the adoption and patterns of antiretroviral drug use and in the incidence of AIDS-defining illness (ADI) between the 2 countries, however, and there has not been a direct comparison of clinical response between Brazil and the United States. We sought to determine if there have been differences in the clinical response to HAART from HIV clinical practices in the United States and Brazil. METHODS: We compared 2 similarly designed clinical cohorts from Baltimore, Maryland and Rio de Janeiro, Brazil. Patients who started HAART from 1997 to 2004 were compared for HIV-1 RNA suppression and CD4+ T-lymphocyte count change by 1 year of therapy and for development of an ADI up to 6 years of follow-up. A total of 1368 patients from Baltimore and 1045 patients from Rio de Janeiro were studied. RESULTS: There was no difference by location in achieving an HIV-1 RNA level <400 copies/mL (46.9% in Rio de Janeiro, 50.8% in Baltimore), in the log change in HIV-1 RNA level (-1.65 log in Rio de Janeiro, - 1.63 log in Baltimore), or in the change in CD4 count (116 cells/mm3 in Rio de Janeiro, 122 cells/mm3 in Baltimore) by 12 months after starting HAART. By Kaplan-Meier analysis and Cox regression adjusted for demographic and clinical prognostic factors, there was no difference by location in development of the first ADI after starting HAART (relative hazard = 1.02; 95% confidence interval: 0.82 to 1.25 for Rio de Janeiro vs. Baltimore). The most commonly occurring ADI in Rio de Janeiro was tuberculosis (27.7% of patients), and the most commonly occurring ADI in Baltimore was esophageal candidiasis (36.8% of patients). CONCLUSIONS: There were only minor differences in clinical response to the use of HAART comparing Rio de Janeiro with Baltimore, despite differences in patterns of antiretroviral drug use and ADI incidence. This analysis indicates that HAART can be similarly effective in treating HIV/AIDS in countries with different economies.     

Psychiatric illness and virologic response in patients initiating highly active antiretroviral therapy

BACKGROUND: Mental illness (MI) and substance abuse (SA) are common in HIV-positive patients. MI/SA consistently predict poorer antiretroviral adherence, suggesting that affected patients should be at higher risk of poor virologic and immunologic response to highly active antiretroviral therapy (HAART). PARTICIPANTS: 198 HAART-naive patients initiated HAART at an academic medical center serving a heterogeneous population. METHODS: Participants were assigned a predicted probability from 0 to 1 of having each of the following: (1) any mood, anxiety, or substance use disorder; (2) clinically relevant depression; (3) alcohol abuse/dependence; and (4) drug abuse/dependence. Probabilities were based on responses to questions on an MI/SA screening instrument (Substance Abuse and Mental Illness Symptoms Screener [SAMISS]) and other clinical and sociodemographic characteristics and were derived using predictive logistic regression modeling from a separate validation study of the SAMISS compared with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnoses. Using survival analysis techniques, we assessed baseline predicted probability of psychiatric illness as a predictor of time from HAART initiation to virologic suppression (first viral load [VL] <400 copies/mL), from HAART initiation to overall virologic failure (first VL >or=400 copies/mL after suppression, time set to 0 for patients never achieving suppression), from virologic suppression to virologic rebound (first VL >or=400 copies/mL), and from HAART initiation to immunologic failure (first CD4 cell count lower than baseline). RESULTS: A higher predicted probability of any psychiatric disorder was associated with a slower rate of virologic suppression (adjusted hazard ratio [aHR] = 0.86 per 25% increment, 95% confidence interval [CI]: 0.75 to 0.98) and a faster rate of overall virologic failure (aHR = 1.22, 95% CI: 1.06 to 1.40). Associations with other outcomes were consistent in direction but not statistically significant. Predicted probability of depression was associated with slower virologic suppression (aHR = 0.79, 95% CI: 0.63 to 0.98), and predicted probabilities of alcohol and drug abuse/dependence was associated with faster overall virologic failure (aHR = 1.37, 95% CI: 1.08 to 1.74 and aHR = 1.18, 95% CI: 1.00 to 1.39, respectively). CONCLUSIONS: These results are consistent with an inferior virologic response to first HAART among patients with concurrent mood, anxiety, and substance use disorders, suggesting a clinical benefit to identification and treatment of psychiatric illness among patients initiating antiretroviral therapy.     

Highly active antiretroviral therapy interruption: predictors and virological and immunologic consequences

OBJECTIVE: To characterize the magnitude and the predictors of highly active antiretroviral therapy (HAART) interruption (TI) and to investigate its immunologic and virological consequences. METHODS: Using Concerted Action on Seroconversion to AIDS and Death in Europe data from 8,300 persons with well-documented seroconversion dates, we identified subjects with stable first HAART (for at least 90 days) not initiated during primary infection. A TI was defined as an interruption of all antiretroviral therapy drugs for at least 14 days. RESULTS: Of 1,551 subjects starting HAART, 299 (19.3%) interrupted treatment. Median (interquartile range) duration of the TI was 189 (101-382) days. The cumulative probability (95% confidence interval) of TI at 2 years was 15.9% (14.0%-18.1%). Women were more likely to have a TI than men in the same exposure group (35.8% vs 24.2% among drug users, 22.1% vs 13.3% among heterosexuals; P < 0.05). Higher baseline viremia and poor immunologic response to HAART were associated with higher probabilities of TI. Median (interquartile range) individual CD4 cell loss during TI was 94 (1-220) cells/microL. Older age at HAART (>40 yr), lower pre-HAART nadir (<200 cells/microL), and lower CD4 at start of TI (<350 cells/microL) were significantly associated with greater relative CD4 loss during TI. CONCLUSIONS: We estimate that almost 1 in 6 subjects on HAART interrupts treatment by 2 years. Further research is needed to investigate the reasons why TI is higher in women. We have identified characteristics of subjects with the greatest risk for CD4 loss in whom TI may have greater risks.     

Clinical and immunologic progression in HIV-infected US women before and after the introduction of highly active antiretroviral therapy

OBJECTIVE: To examine factors associated with clinical and immunologic HIV disease progression in a cohort of US women. DESIGN: Analysis of data from a prospective, longitudinal, case-control study of HIV-infected women followed every 6 months for 7 years. SETTING: Four urban clinical centers in the United States. PARTICIPANTS: 648 HIV-infected women who did not have AIDS at time of entry into the study. MEASUREMENTS: Structured clinical and behavioral interviews; protocol-directed physical examinations; CD4 lymphocyte counts; plasma HIV RNA; infectious pathogen serologies.RESULTS With 2304 women-years of follow-up, 46.1% of the women developed AIDS; however, 93.3% of the diagnoses were based on CD4 counts dropping to <200 cells/mm(3). Only 10.6% of the women with CD4 counts <200 cells/mm(3) developed an opportunistic infection. Baseline CD4 count was the strongest predictor of subsequent clinical progression. Illicit substance use, multiple pregnancies, demographic variables, and other infections were not associated with progression. Among women with CD4 counts >500 cells/mm(3) at baseline, those who were anemic or had hepatitis C were more likely to progress to AIDS. By the end of the study, only 52% of the participants were on highly active antiretroviral therapy (HAART). CONCLUSIONS: Despite underutilization of HAART in this multicenter cohort of urban women, opportunistic infections were uncommon, despite CD4 declines.