A critical assessment of the prognostic value of HIV-1 RNA levels and CD4+ cell counts in HIV-infected patients. The Swiss HIV Cohort Study

A click chemistry amplified nanopore assay for ultrasensitive quantification of HIV-1 p24 antigen in clinical samples

Despite major advances in HIV testing, ultrasensitive detection of early infection remains challenging, especially for the viral capsid protein p24, which is an early virological biomarker of HIV-1 infection. Here, To improve p24 detection in patients missed by immunological tests that dominate the diagnostics market, we show a click chemistry amplified nanopore (CAN) assay for ultrasensitive quantitative detection. This strategy achieves a 20.8 fM (0.5 pg/ml) limit of detection for HIV-1 p24 antigen in human serum, demonstrating 20~100-fold higher analytical sensitivity than nanocluster-based immunoassays and clinically used enzyme-linked immunosorbent assay, respectively. Clinical validation of the CAN assay in a pilot cohort shows p24 quantification at ultra-low concentration range and correlation with CD4 count and viral load. We believe that this strategy can improve the utility of p24 antigen in detecting early infection and monitoring HIV progression and treatment efficacy, and also can be readily modified to detect other infectious diseases.

Trends in Racial/Ethnic Disparities Among Patients Living with HIV in Texas, 1996 to 2013

National studies show that Blacks with HIV have higher mortality rates compared to Whites. This study aimed to identify trends in Black racial disparities among Texas residents living with HIV. Using HIV surveillance data from the Texas Department of State Health Services, a cohort of HIV-diagnosed patients (N = 70,996) were identified and grouped according to year of diagnosis, 1996-1997 (T1), 1998-2006 (T2), 2007-2010 (T3), and 2011-2013 (T4). Survival analysis was used to examine racial differences in death rate (analysis 1) and clinical progression to AIDS (analysis 2) for each subcohort, using Blacks as the reference group. In analysis 1, Whites (hazard ratio, HR = 0.80, 95% confidence interval, CI = 0.74-0.87, p < 0.001; HR = 0.82, 95% CI = 0.78-0.87, p < 0.001; respectively) and Hispanics (HR = 0.72, 95% CI = 0.66-0.79, p < 0.001; HR = 0.77, 95% CI = 0.74-0.81, p < 0.001, respectively) had lower death rates in T1 and T2. This remained significant after adjusting for covariates. In T3, death rate was higher for Hispanics after adjustment (HR = 1.13, 95% CI = 1.00-1.28, p < 0.05). In T4, death rate was higher for Whites (HR = 1.66, 95% CI = 1.30-2.13, p < 0.001) and Hispanics (HR = 1.66, 95% CI = 1.34-2.06, p < 0.001). These relationships became non-significant after adjusting for covariates. In analysis 2, the rate of clinical progression to AIDS was higher for Hispanics in all subcohorts. The significance remained after adjusting for covariates. The rate of clinical progression to AIDS was lower for Whites after adjustments in T2 and T3. Additional studies are needed to understand factors that may explain this unexpected finding of improved survival for Blacks over time. Such studies may inform decision-making in HIV care to reduce Black HIV disparities.

Comparison of Single and Boosted Protease Inhibitor Versus Nonnucleoside Reverse Transcriptase Inhibitor–Containing cART Regimens in Antiretroviral-Naïve Patients Starting cART After January 1, 2000

BACKGROUND

Few published studies have considered both the short- and long-term virologic or immunologic response to combination antiretroviral therapy (cART) and the impact of different cART strategies.

PURPOSE

To compare time to initial virologic (<500 copies/mL) or immunologic (>200/mm3 cell increase) response in antiretroviral-naïve patients starting either a single protease inhibitor (PI; n = 183), a ritonavir-boosted PI regimen (n = 197), or a nonnucleoside reverse transcriptase inhibitor (NNRTI)-based cART regimen (n = 447) after January 1, 2000, and the odds of lack of virologic or immunologic response at 3 years after starting cART.

METHOD

Cox proportional hazards models and logistic regression.

RESULTS

After adjustment, compared to patients taking an NNRTI-regimen, patients taking a single-PI regimen were significantly less likely to achieve a viral load (VL) <500 copies/mL (relative hazard [RH] 0.74, 95% CI 0.54-0.84, p = .0005); there was no difference between the boosted-PI regimen and the NNRTI regimen (p = .72). There were no differences between regimens in the risk of >200/mm3 CD4 cell increase after starting cART (p > .3). At 3 years after starting cART, patients taking a single-PI-based regimen were more likely to not have virologic suppression (<500 copies/mL; odds ratio [OR] 1.60, 95% CI 1.06-2.40, p = .024), while there were no differences in the odds of having an immunologic response (>200/mm3 increase; p > .15). This model was adjusted for CD4 and VL at starting cART, age, prior AIDS diagnosis, year of starting cART, and region of Europe.

CONCLUSION

Compared to patients starting an NNRTI-based regimen, patients starting a single-PI regimen were less likely to be virologically suppressed at 3 years after starting cART. These results should be interpreted with caution, because of the potential biases associated with observational studies. Ultimately, clinical outcomes, such as new AIDS diagnoses or deaths, will be the measure of efficacy of cART regimens, which requires the follow-up of a very large number of patients over many years.

[Benefit and pitfalls in the use of data from surrogate endpoint trials for clinical decision making]

Ideally clinicians should base their treatment decision on results from randomised controlled trials which include patient-important outcomes, such as quality of life, prevented disease events or death. Conducting such trials often involves large samples sizes and extended follow-up periods. Therefore, researchers have aimed to conduct trials with surrogate endpoints by substituting patient-important outcomes in order to reduce sample size and observation time. Surrogate endpoints are outcomes that substitute for direct measures of how a patient feels, functions, or survives. In many countries drugs are approved based on data from surrogate endpoint trials. Recently, a controversy has evolved on the reliability of results generated from surrogate endpoint trials driven by unanticipated side effects or severe toxicity leading to the withdrawal of drugs that were solely approved based on evidence from surrogate endpoint trials. We present some recent examples and criteria how clinicians can critically evaluate the validity of claims by experts or the pharmaceutical industry in regard to the expected patients' benefit from drugs approved by results from surrogate endpoint trials.

Risk factors associated with low CD4+ lymphocyte count among HIV-positive pregnant women in Nigeria

OBJECTIVE

To determine the risk factors for CD4+ lymphocyte counts of 200 cells/mm(3) or lower in HIV-positive pregnant women in Nigeria.

METHOD

A cross-sectional data analysis from a prospective cohort of 515 HIV-positive women attending a prenatal clinic. Risk of a low CD4+ count was estimated using logistic regression analysis.

RESULTS

CD4+ lymphocyte counts of 200 cells/mm(3) or lower (280+/-182 cells/mm(3)) were recorded in 187 (36.3%) out of 515 HIV-positive pregnant women included in the study. Low CD4+ count was associated with older age (adjusted odds ratio [aOR] 10.71; 95% confidence interval [CI], 1.20-95.53), lack of condom use (aOR, 5.16; 95% CI, 1.12-23.8), history of genital ulcers (aOR, 1.78; 95% CI, 1.12-2.82), and history of vaginal discharge (aOR; 1.62; 1.06-2.48).

CONCLUSIONS

Over 35% of the HIV-positive pregnant women had low CD4+ counts, indicating the need for treatment. The findings underscore the need to integrate prevention of mother-to-child transmission with HIV treatment and care, particularly services for sexually transmitted infections.

Clinical prognostic value of RNA viral load and CD4 cell counts during untreated HIV-1 infection--a quantitative review

Background

The prognostic value of CD4 counts and RNA viral load for identifying treatment need in HIV-infected individuals depends on (a) variation within and among individuals, and (b) relative risks of clinical progression per unit CD4 or RNA difference.

Methodology/Principal Findings

We reviewed these measurements across (a) 30 studies, and (b) 16 cohorts of untreated seropositive adults. Median within-population interquartile ranges were 74,000 copies/mL for RNA with no significant change during the course of infection; and 330 cells/µL for CD4, with a slight proportional increase over infection. Applying measurement and physiological fluctuations observed on chronically infected patients, we estimate that 45% of population-level variation in RNA, and 25% of variation in CD4, were due to within-patient fluctuations. Comparing a patient with RNA at upper 75^th centile with a patient at median RNA, 5-year relative risks were 1.4 (95% CI 1.2–1.7) for AIDS and 1.5 (1.3–1.9) for death, without change over the course of infection. In contrast, for a patient with CD4 count at the lower 75^th centile, relative risks increased from 1.0 at seroconversion to maxima of 6.3 (4.4–8.9) for AIDS and 5.5 (2.7–10.1) for death by year 6, when the population median had fallen to 300 cells/µL. Below 300 cells/µL, prognostic power did not increase, due to a narrower CD4 range.

Conclusions

Findings support the current WHO recommendation (used with clinical criteria) to start antiretroviral treatment in low-income settings at CD4 thresholds of 200–350 cells/µL, without pre-treatment RNA monitoring – while not precluding earlier treatment based on clinical, socio-demographic or public health criteria.

Change over time of mortality predictors after HAART initiation in a Senegalese cohort

BACKGROUND

In 1998, Senegal was among the first sub-Saharan African countries to launch a Highly active anti-retroviral therapy (HAART) access program. Initial studies have demonstrated the feasibility and efficacy of this initiative. Analyses showed a peak of mortality short after starting HAART warranting an investigation of early and late mortality predictors.

METHODS

404 HIV-1-infected Senegalese adult patients were enrolled and data censored as of September 2005. Predictor effects on mortality were first examined over the whole follow-up period (median 46 months) using a Cox model and Shoenfeld residuals. Then, changes of these effects were examined separately over the early and late treatment periods; i.e., less and more than 6-month follow-up.

RESULTS

During the early period, baseline body mass index and baseline total lymphocyte count were significant predictors of mortality (Hazard Ratios 0.82 [0.72-0.93] and 0.80 [0.69-0.92] per 200 cell/mm3, respectively) while baseline viral load was not significantly associated with mortality. During the late period, viro-immunological markers (baseline CD4-cell count and 6-month viral load) had the highest impact. In addition, the viral load at 6-month was a significant predictor (HR = 1.42 [1.20-1.66]).

CONCLUSION

In this cohort, impaired clinical status could explain the high early mortality rate while viro-immunological markers were rather predictors of late mortality.

Determinants of discontinuation of initial highly active antiretroviral therapy regimens in a US HIV-infected patient cohort

OBJECTIVES

Optimization of initial highly active antiretroviral therapy (HAART) for complete viral suppression and better tolerability is paramount for the prognosis of HIV-infected patients. Observational studies provide a better means than clinical trials of studying the determinants of discontinuation in actual practice.

METHODS

A longitudinal cohort of US HIV-positive patients who initiated HAART for the first time from 1996 to 2003 were included in the analysis. Stratified Cox proportional hazards models, considering time-updated viral load and CD4 count data, were developed for analyzing time to first discontinuation.

RESULTS

A total of 3414 antiretroviral-naive HAART patients were identified. In a median follow-up period of 211 days (mean 324 days), 628 patients (18.4%) reportedly discontinued the HAART regimen because of drug toxicity, 456 (13.4%) because of non-compliance, and 257 (7.5%) because of treatment failure. In addition to the recorded reasons for discontinuation, black ethnicity [relative risk (RR) 1.28, 95% confidence interval (CI) 1.13-1.45], current smoking (RR 1.33, CI 1.18-1.50), high pill burden (RR 1.44, CI 1.22-1.70), and recent viral control (RR 0.63, CI 0.56-0.70) were all predictive of discontinuation. Only high pill burden (>15 pills/day), which is considered to be a surrogate for treatment regimen complexity, and the most recent poor viral control (HIV RNA) were found to be consistently associated with a higher likelihood of discontinuation.

CONCLUSIONS

Risk factors other than physician- or patient-reported reasons play a role in discontinuation of initial HAART regimens. Identification of these risk factors and simplification of treatment regimens in those at high risk for discontinuation appear to be necessary in order to maximize the effectiveness of HAART regimens.

Optimized virus disruption improves detection of HIV-1 p24 in particles and uncovers a p24 reactivity in patients with undetectable HIV-1 RNA under long-term HAART

HIV-1 p24 antigen (p24) measurement by signal amplification-boosted ELISA of heat-denatured plasma is being evaluated as an alternative to HIV-1 RNA quantitation in resource-poor settings. Some observations suggested that virion-associated p24 is suboptimally detected using Triton X-100-based virus dissociation buffer (kit buffer). A new reagent (SNCR buffer) containing both denaturing and non-denaturing detergents was therefore developed and evaluated. The SNCR buffer increased the measured p24 concentration about 1.5- to 3-fold in HIV-negative plasma reconstituted with purified HIV-1 particles, while not increasing the background. Among 127 samples of HIV-1-positive patients with moderate to high concentrations of HIV-1 RNA the increase was about threefold across the entire concentration range (P < 0.0001). Specificity before neutralization among prospectively tested clinical samples ruled HIV-negative was 828 of 845 (98.0%) for the SNCR buffer and 464 of 479 (96.9%) for kit buffer. Specificity after confirmatory neutralization of reactive samples or a follow-up test was 100% with either buffer. Surprisingly, the SNCR buffer revealed a p24 reactivity in 115 of 187 samples (61.5%) from adult patients exhibiting undetectable HIV-1 RNA below 5 copies/ml for a duration of 6-30 months under HAART (3.7% with kit buffer). The rate of p24 reactivity in these patients did not decrease with duration of HAART. In conclusion, the SNCR buffer improves the detection of particle-associated HIV-1 p24, thereby increasing the measured p24 concentration in samples with medium to high HIV-1 RNA. It also uncovers the presence of a p24 reactivity, whose identity remains to be determined, in a significant fraction of samples with undetectable HIV-1 RNA under long-term HAART.

Antiretroviral therapy 2006: Pharmacology, applications, and special situations

As we approach the completion of the first 25 years of the human immunodeficiency virus (HIV) epidemic, there have been dramatic improvements in the care of patients with HIV infection. These have prolonged life and decreased morbidity. There are twenty currently available antiretrovirals approved in the United States for the treatment of this infection. The medications, including their pharmacokinetic properties, side effects, and dosing are reviewed. In addition, the current approach to the use of these medicines is discussed. We have included a section addressing common comorbid conditions including hepatitis B and C along with tuberculosis.

Cost-effectiveness of screening for HIV in the era of highly active antiretroviral therapy

BACKGROUND

The costs, benefits, and cost-effectiveness of screening for human immunodeficiency virus (HIV) in health care settings during the era of highly active antiretroviral therapy (HAART) have not been determined.

METHODS

We developed a Markov model of costs, quality of life, and survival associated with an HIV-screening program as compared with current practice. In both strategies, symptomatic patients were identified through symptom-based case finding. Identified patients started treatment when their CD4 count dropped to 350 cells per cubic millimeter. Disease progression was defined on the basis of CD4 levels and viral load. The likelihood of sexual transmission was based on viral load, knowledge of HIV status, and efficacy of counseling.

RESULTS

Given a 1 percent prevalence of unidentified HIV infection, screening increased life expectancy by 5.48 days, or 4.70 quality-adjusted days, at an estimated cost of 194 dollars per screened patient, for a cost-effectiveness ratio of 15,078 dollars per quality-adjusted life-year. Screening cost less than 50,000 dollars per quality-adjusted life-year if the prevalence of unidentified HIV infection exceeded 0.05 percent. Excluding HIV transmission, the cost-effectiveness of screening was 41,736 dollars per quality-adjusted life-year. Screening every five years, as compared with a one-time screening program, cost 57,138 dollars per quality-adjusted life-year, but was more attractive in settings with a high incidence of infection. Our results were sensitive to the efficacy of behavior modification, the benefit of early identification and therapy, and the prevalence and incidence of HIV infection.

CONCLUSIONS

The cost-effectiveness of routine HIV screening in health care settings, even in relatively low-prevalence populations, is similar to that of commonly accepted interventions, and such programs should be expanded.

[Predictors of progression and death in patients with advanced HIV infection in the era of highly active antiretroviral therapy]

INTRODUCTION

To assess the factors associated with progression of infection and death in HIV-positive patients with severe immunodepression in the era of highly active antiretroviral therapy (HAART).

METHODS

We studied 146 HIV-infected patients with < 100 x 10(6)/L CD4+ lymphocytes and positive cytomegalovirus (CMV) serology enrolled between December 1997 and October 1998 and prospectively followed a median of 12.1 months. The main outcome measures were progression of HIV infection, defined as the appearance of a new AIDS-defining disease (CDC category C) or death. HIV viral load, lymphocyte count (CD4+ and CD8+), HAART administration and other clinical variables were evaluated at baseline. CMV viremia (determined by PCR) and HAART efficacy were recorded during follow-up.

RESULTS

Progression was observed in 40% of patients and 17% died. Factors associated with progression or death were CD4+ lymphocyte count less than 50 x 10(6)/L, CD8+ lymphocyte count less than 500 x 10(6)/L, HIV viral load more than 300,000 copies RNA/mL, CMV viremia, and absence or inefficacy of HAART. In the multivariate model, absence of HAART and low CD4+ and CD8+ counts remained statistically associated with progression, but the only variable associated with death was CMV viremia.

CONCLUSIONS

In patients with advanced HIV infection, CD4+ and CD8+ cell count and HAART were the most important factors related to progression, and CMV viremia was the strongest predictor of death.

Predictors of trend in CD4-positive T-cell count and mortality among HIV-1-infected individuals with virological failure to all three antiretroviral-drug classes

BACKGROUND

Treatment strategies for patients in whom HIV replication is not suppressed after exposure to several drug classes remain unclear. We aimed to assess the inter-relations between viral load, CD4-cell count, and clinical outcome in patients who had experienced three-class virological failure.

METHODS

We undertook collaborative joint analysis of 13 HIV cohorts from Europe, North America, and Australia, involving patients who had had three-class virological failure (viral load >1000 copies per mL for >4 months). Regression analyses were used to quantify the associations between CD4-cell-count slope, HIV-1 RNA concentration, treatment information, and demographic characteristics. Predictors of death were analysed by Cox's proportional-hazards models.

FINDINGS

2488 patients were included. 2118 (85%) had started antiretroviral therapy with single or dual therapy. During 5015 person-years of follow-up, 276 patients died (mortality rate 5.5 per 100 person-years; 3-year mortality risk 15.3% (95% CI 13.5-17.3). Risk of death was strongly influenced by the latest CD4-cell count with a relative hazard of 15.8 (95% CI 9.28-27.0) for counts below 50 cells per microL versus above 200 cells per microL. The latest viral load did not independently predict death. For any given viral load, patients on treatment had more favourable CD4-cell-count slopes than those off treatment. For patients on treatment and with stable viral load, CD4-cell counts tended to be increasing at times when the current viral load was below 10000 copies per mL or 1.5 log10 copies per mL below off-treatment values.

INTERPRETATION

In patients for whom viral-load suppression to below the level of detection is not possible, achievement and maintenance of a CD4-cell count above 200 per microL becomes the primary aim. Treatment regimens that maintain the viral load below 10000 copies per mL or at least provide 1.5 log10 copies per mL suppression below the off-treatment value do not seem to be associated with appreciable CD4-cell-count decline.

Citalopram treatment of major depressive disorder in Hispanic HIV and AIDS patients: a prospective study

Fourteen Hispanic and six non-Hispanic outpatients with HIV-spectrum illness and major depressive disorder were enrolled in a 6-week, open-label, flexible-dose study of citalopram (dose range=10-40 mg/day). The depressive symptoms of 50% of the 14 patients who completed the study responded to citalopram (mean dose=34 mg/day). The treatment response rate, effective citalopram dose, total number of reported adverse events, and attrition rate did not differ between the ethnic groups. Two patients discontinued because of adverse events (rash, nausea), and four patients discontinued because of noncompliance with the protocol. The findings suggest that citalopram is an effective and well-tolerated antidepressant for Hispanic and non-Hispanic HIV-infected patients.

The role of sexually transmitted diseases in HIV transmission

More than 42 million people worldwide are now infected with HIV, in spite of sustained prevention activities. Although the spread of HIV has been primarily sexual, epidemiological studies have indicated that the efficiency of the spread of HIV is poor, perhaps as infrequently as 1 in every 1,000 episodes of sexual intercourse. However, sexually transmitted diseases (STDs) that cause ulcers or inflammation greatly increase the efficiency of HIV transmission--by increasing both the infectiousness of, and the susceptibility to HIV infection. STDs might be particularly important in the early stages of a localized HIV epidemic, when people with risky sexual behaviour are most likely to become infected. In China, eastern Europe and Russia, there has been a remarkable increase in the incidence of STDs in recent years, and this is reflected in the rapid increase in the spread of HIV in these areas. Targeted STD detection and treatment should have a central role in HIV prevention in these emerging epidemics.

Viral RNA and p24 Antigen as Markers of HIV Disease and Antiretroviral Treatment Success

HIV-1 RNA has become the standard for monitoring antiretroviral therapies. Dogma predicts, however, that a viral protein like p24 should be at least as good a marker of HIV disease activity, provided that it is measured with sufficient sensitivity and accuracy. Simple modifications including use of a more efficient virus lysis buffer, heat-mediated destruction of antibodies interfering with antigen detection, and tyramide signal amplification for increased sensitivity have highly improved the HIV-1 p24 antigen assay. The p24 antigen assay is inferior to RT-PCR in detecting viral particles, but the presence of extraviral p24 antigen in most samples makes largely up for this. p24 antigen testing is similarly sensitive and specific in diagnosing pediatric HIV infection, in predicting CD4+ T cell decline and clinical progression at early and late stage of infection, and suitable for antiretroviral treatment monitoring in both adults and children. Notably, p24 antigen was measurable even in patients with stably suppressed viremia, and its concentrations were correlated negatively with the concentrations of CD4+ T cells and positively with the concentrations of activated CD8+ T cell subsets. p24 antigen is an excellent marker of HIV expression and disease activity and can be used in the same fields of application as HIV RNA is used. The test is validated for subtype B, but requires further studies for non-B subtypes.

A prospective trial of sustained-release bupropion for depression in HIV-seropositive and AIDS patients

To date, the authors know of no prospective studies of sustained-release bupropion in depressed HIV-seropositive patients. The purpose of this study was to evaluate the efficacy and tolerability of sustained-release bupropion in 20 depressed HIV-positive adult outpatients. Twenty outpatients with HIV spectrum illness, a DSM-IV-diagnosed major depressive disorder confirmed with the Structured Clinical Interview for DSM-IV, and Mini-Mental State Examination scores >20 were recruited into a 6-week, open-label, flexible-dose study of sustained-release bupropion (100-300 mg/day). Twelve patients (60%) responded to sustained-release bupropion at a mean dose of 265 mg/day. Five patients (25%) discontinued study participation secondary to adverse events. Preliminary findings suggest that sustained-release bupropion is effective for the treatment of depression in HIV-positive patients, regardless of HIV clinical staging. Furthermore, it appears to be well tolerated in patients with AIDS-related medical conditions.

Supplementation with antioxidant vitamins prevents oxidative modification of DNA in lymphocytes of HIV-infected patients

There is evidence suggesting that patients infected with human immunodeficiency virus (HIV) are under chronic oxidative stress. In the present study, the level of oxidatively modified bases in lymphocyte DNA and some other parameters of oxidative stress were measured in HIV-infected patients (n = 30), as well as in control groups (10 healthy volunteers and 15 HIV-seronegative injected drug users). Additional experiments were conducted using lymphocyte DNA samples from asymptomatic seropositive, HIV-infected patients who were supplemented with antioxidant vitamins A, C, and E or received placebo. Significant increases in the amount of the modified DNA bases were observed in HIV-infected patients when compared with the control group. The concentration of thiobarbituric acid reactive substances (TBARS) was higher and activities of antioxidant enzymes (superoxide dismutase and catalase) were lower in the group of HIV-infected patients in comparison to the control group. Vitamin supplementation resulted in the significant decrease in the levels of all modified DNA bases when compared to the patients who received placebo. The reduction of TBARS and the restoration of the activity of the enzymes were also observed. Our data suggest that people infected with HIV can benefit from treatment with antioxidant vitamins.

Viral load as an independent risk factor for opportunistic infections in HIV-infected adults and adolescents

OBJECTIVE

We investigated whether HIV plasma RNA (viral load; VL) predicts risk for opportunistic infections (OI) in HIV-infected persons, independent of CD4 lymphocyte count and other factors that might affect disease outcome.

METHODS

Among persons who had initiated antiretroviral therapy (ART), we studied the risk for OI following a VL measurement in the Centers for Disease Control and Prevention Adult and Adolescent Spectrum of HIV Disease (ASD) Project, a medical record review study of HIV-infected persons in 11 US cities. Analysis was limited to persons who had initiated ART and who had VL data, primarily from the period 1996-1999. Persons were considered at risk for OI for 1 to 6 months after a given VL; risk for OI was assessed using a Poisson multiple regression model controlling for CD4 lymphocyte count, ART, and other variables potentially associated with development of OI: history of AIDS OI, age, sex, race, HIV risk category, OI prophylaxis, and calendar year.

RESULTS

Although decreasing CD4 count was the strongest predictor of risk for OI [relative risk (RR), 13.3 for persons with CD4 lymphocyte count < 50 x 10(6)/l compared with persons with CD4 lymphocyte count > or = 500 x 10(6)/l], increasing VL was independently associated with increased risk [RR, 1.6, 1.9, 2.7, and 3.5 for VL of 7000-19 999, 20 000-54 999, 55 000-149 999, and > or = 150 000 copies/ml (by reverse transcription-PCR), respectively, compared with VL < 400]. Similar results were obtained when the risk period was reduced to 5, 4, 3, and 2 months after VL measurement.

CONCLUSIONS

VL is an independent risk factor for OI and should be considered in special situations, such as in decisions to discontinue primary or secondary OI prophylaxis after CD4 lymphocyte counts have increased in response to ART.

Do HIV type 1 RNA levels provide additional prognostic value to CD4(+) T lymphocyte counts in patients with advanced HIV type 1 infection?

Our objective was to assess whether HIV-1 RNA levels provide additional prognostic information beyond CD4(+) T lymphocyte counts in the prediction of subsequent HIV-1 disease progression among patients with advanced HIV-1 disease. In a nested case-control study conducted in patients with baseline CD4(+) T lymphocyte counts < 300 cells/mm(3) and receiving nucleoside reverse transcriptase inhibitors, 102 patients who progressed to an AIDS-defining event or death were matched within 10 CD4(+) T lymphocyte cells/mm(3) to patients who did not progress. The relationship between plasma HIV-1 RNA levels and HIV-1 disease progression was studied using conditional logistic regression analysis, which adjusts for the matching by baseline CD4(+) T lymphocytes. We observed a 0.10 log(10) copies/ml difference in baseline HIV-1 RNA levels between cases and their matched controls (p = 0.027). The relative risk for HIV-1 disease progression increased with increasing baseline HIV-1 RNA levels (odds ratio [OR] for a 3-fold higher HIV-1 RNA level, 1.42; 95% confidence interval [CI], 1.08--1.86), and remained important when also controlling for clinical status at baseline and CD4(+) T lymphocytes at 2 months (p = 0.038). Higher baseline HIV-1 RNA levels were associated with HIV-1 disease progression among patients with a baseline CD4(+) T lymphocyte count of 100 cells/mm(3) or greater (OR, 1.80; 95% CI, 1.15--2.81), but not among patients with a baseline CD4(+) T lymphocyte count < 100 cells/mm(3) (OR, 1.09; 95% CI, 0.73--1.63). We concluded that HIV-1 RNA levels predict subsequent HIV-1 disease progression independent of CD4(+) T lymphocyte counts. The magnitude and importance of the prognostic information contained in the HIV-1 RNA levels appear to depend on the CD4(+) T lymphocyte counts.

Modeling changes in CD4-positive T-lymphocyte counts after the start of highly active antiretroviral therapy and the relation with risk of opportunistic infections: the Aquitaine Cohort, 1996-1997

After initiation of a treatment for human immunodeficiency virus type 1 infection containing a protease inhibitor, immune restoration associated with increases in CD4-positive (CD4+) T lymphocyte count may be delayed. In a sample of patients who had been prescribed protease inhibitors for the first time, the authors tested to see whether there was a minimal duration of CD4+ cell count increase before the increase had an impact on the occurrence of opportunistic infections. The evolution (difference between time t and baseline) of CD4+ cell count was modeled using a mixed effects linear model. Changes in CD4+ count estimated by this model were then included as time-dependent covariates in a proportional hazards model. Finally, the authors tested for the existence of a CD4+ change x time interaction. The authors used a sample of 553 French patients first prescribed protease inhibitors in 1996 and followed for a median of 16 months. During the first 120 days, there was no association between CD4+ change and the rate of opportunistic infections. After 120 days, each 50-cell/mm3 increase in CD4+ count was associated with a 60% (95% confidence interval: 45, 72) reduction in the incidence of opportunistic infections. These results, based on modeling of CD4+ cell response, at least indirectly reinforce the concept of a delayed but possible immune recovery with the use of protease inhibitors. The findings support the potential for interruption of certain types of prophylaxis against opportunistic infections under reasonable conditions of duration of antiretroviral therapy and sustained CD4+ cell response.

Reasons for modification and discontinuation of antiretrovirals: results from a single treatment centre

OBJECTIVE

To describe the reasons for, and factors associated with, modification and discontinuation of highly active antiretroviral therapy (HAART) regimens at a single clinic.

SUBJECTS

A total of 556 patients who started HAART at the Royal Free Hospital were included in analyses. Modification was defined as stopping or switching any antiretrovirals in the regimen, whereas discontinuation was defined as the simultaneous stopping of all antiretrovirals included in the initial regimen. Reasons were classified as immunological/virological failure (IVF) and toxicities and patient choice/poor compliance (TPC).

RESULTS

The median CD4 count at starting HAART was 171 x 10(6) cells/l and viral load 5.07 log copies/ml. During a median follow-up of 14.2 months, 247 patients (44.4%) modified their HAART regimen, 72 due to IVF (29.1%) and 159 due to TPC (64.4%) and a total of 148 patients (26.6%) discontinued HAART. Older patients were less likely to modify HAART [relative hazard (RH), 0.73 per 10 years; P = 0.0008], as were previously treatment-naive patients (RH, 0.65; P = 0.0050), those in a clinical trial (RH, 0.64; P = 0.027) and those who started nelfinavir (RH, 0.57; P = 0.035). Patients who started with four or more drugs (RH, 2.21, P < 0.0001), who included ritonavir in the initial regimen (RH, 1.41; P = 0.035) or who had higher viral loads during follow-up (RH per log increase, 1.51; P < 0.0001) were more likely to modify HAART.

CONCLUSIONS

There was a high rate of modification and discontinuation of HAART regimens in the first 12 months, particularly due to toxicities, patient choice or poor compliance.

Efavirenz: a pharmacoeconomic review of its use in HIV infection

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) used in the treatment of patients with HIV infection. Both US and British treatment guidelines for HIV infection recommend NNRTI- or protease inhibitor-based combinations [i.e. with nucleoside reverse transcriptase inhibitors (NRTIs)] as first-line treatmentoptions in the management of HIV disease. Results of a pivotal randomised study (DMP 266-006) comparing efavirenz- versus indinavir-based triple combination therapy in patients with HIV infection (the majority of whom were antiretroviral therapy-naive) showed the efavirenz-based regimen was better tolerated and had greater success in achieving reductions in viral load below the limit of detection. These and other clinical data were incorporated into economic models in 2 analyses, one conducted in the US and the other in Canada. The US analysis examined long term clinical and economic outcomes predicted on the basis of response (viral load and CD4+ cell counts), tolerability and willingness to adhere to therapy. The efavirenz-based regimen was the dominant treatment strategy as it was predicted to improve survival and reduce direct medical costs in the US healthcare system. Compared with the indinavir-containing regimen, survival was increased by 11% (absolute difference) and cumulative costs were reduced by $US10,326 per patient (1998 discounted costs) at 5 years after starting treatment with efavirenz-based therapy. The Canadian analysis was conducted from the perspective of the Ontario healthcare system. This study did not consider differences in clinical efficacy between treatment groups, costs of study medication or outcomes beyond 1 year--all factors that would have favoured the efavirenz-based regimen. Of the 2 treatment options, the efavirenz-based regimen was associated with 7.4% lower average annual medical care costs, primarily because of greater costs associated with adverse clinical events with the indinavir-based regimen. In conclusion, current treatment guidelines for HIV infection recognise efavirenz-based combination regimens as a first-line treatment option. A pivotal comparative clinical trial (DMP 266-006) showed a significantly greater virological response to efavirenz- than indinavir-based triple combination therapy, and the efavirenz-based regimen was better tolerated. These clinical data are supported by pharmacoeconomic analyses conducted in the US and Canada, both of which showed lower medical care costs with the efavirenz-based regimen. The US analysis also predicted long term health benefits, such as improved survival, with efavirenz- versus indinavir-based triple combination therapy. These results must be weighed against the inherent difficulties of predicting long term treatment failure rates from short term data, and the limited number of pharmacoeconomic analyses conducted with efavirenz to date.

Economic analysis of initial HIV treatment. Efavirenz- versus indinavir-containing triple therapy

OBJECTIVE

To compare the clinical and economic outcomes associated with triple therapy containing efavirenz or indinavir and 2 nucleoside reverse transcriptase inhibitors (NRTIs; zidovudine and lamivudine) in HIV-positive patients.

DESIGN AND SETTING

An economic model based on viral load and CD4+ cell counts to predict long term outcomes such as progression to AIDS and AIDS-related death was developed and then analysed using data from a randomised clinical trial. Cost estimates from the healthcare system perspective were based on data from 6 state, all-payor databases, the AIDS Cost and Services Utilisation Study, and other literature. Analyses were carried out for time horizons between 5 and 15 years.

PATIENTS AND INTERVENTIONS

HIV-positive patients with limited exposure to NRTIs. Initial regimens consisted of efavirenz or indinavir, each combined with 2 NRTIs. A maximum of 2 switches to other regimens was permitted.

MAIN OUTCOME MEASURES AND RESULTS

The efavirenz-containing triple therapy regimen was predicted to prolong survival at a savings of up to 10,923 US dollars (1998 values) relative to initial therapy with the indinavir-containing regimen. Patients who receive efavirenz are expected to have 11% greater survival at 5 years and fewer treatment failures (28 vs 52%, at 2 years). Overall, the economic and health benefits predicted for the efavirenz-containing regimen were robust to reasonable variation in key parameters.

CONCLUSIONS

The superior clinical trial outcomes for efavirenz-containing regimens should translate into substantial economic and health benefits.

Antiretroviral therapy 2000

As we enter the new millennium, there have been dramatic improvements in the care of patients with HIV infection. These have prolonged life and decreased morbidity and mortality. There are fourteen currently available antiretrovirals approved in the United States for the treatment of this infection. The medications, including their pharmacokinetic properties, side effects, and dosing are reviewed. In addition, the current approach to the use of these medicines is discussed.

Duration of viral suppression in patients on stable therapy for HIV-1 infection is predicted by plasma HIV RNA level after 1 month of treatment

The aim of this study was to assess the predictive value of HIV RNA levels after 1 month of therapy on the long-term virologic outcome in an unselected general population of HIV-infected patients.

DESIGN

Analysis was conducted retrospectively on an ongoing clinical cohort of HIV-positive patients who were receiving antiretroviral treatment. Data on 575 patients were analyzed.

RESULTS

The HIV RNA value at 1 month was significantly correlated with the virologic outcome after 12 and 24 months of therapy (R = 0.258 and R = 0.44, respectively). The predictive value of the 1-month viral load was also statistically significant after stratification for baseline CD4 T-cell counts. Prediction was similar in highly compromised patients (CD4 < or = 100 cells/microl; R = 0.426; p = .001) or in patients with a better immunologic status (R = 0.419; p < .0001). It retained validity in patients who were naive or experienced for antiretroviral therapy.

CONCLUSION

HIV RNA level after 1 month of therapy is a useful prognostic marker in HIV-infected patients. It predicts long-term virologic and immunologic outcome. A cutoff level of 5000 copies/ml identifies patients most likely to fail current therapy. In these patients, a more aggressive strategy or specific diagnostic interventions to clarify the relative influence of viral resistance and/or subtherapeutic regimens is advised.

The values of quantitative serum HIV-1 RNA levels and CD4 cell counts for predicting survival time among HIV-positive individuals with CD4 counts of < or = 50 x 10(6) cells/l

OBJECTIVE

To evaluate the HIV-1 RNA level as a predictor of survival time among individuals with advanced AIDS.

METHODS

The serum HIV-1 RNA level, the CD4 cell count, and other clinical variables were evaluated at baseline, as predictors of survival time, among 56 retrospectively identified HIV-1 positive individuals with < or = 50 x 10(6) CD4 cells/l who attended the Beth Israel Deaconess Medical Center, Division of Infectious Diseases, between 1 July 1989 and 30 September 1993.

RESULTS

During follow-up, 55 of these 56 patients died. The median survival time was 20.5 months. In univariate Cox proportional hazard modeling neither the baseline HIV-1 RNA level nor the CD4 cell count were predictive of survival time. However, in multivariate models longer survival time was associated with the use of trimethoprim-sulphamethoxazole at entry [hazard ratio (HR), 0.42; P = 0.007], whereas shorter survival time was associated with a history of an AIDS-defining illness other than Pneumocystis carinii pneumonia (HR, 2.87; P = 0.007). Correlative analysis revealed a modest correlation of the baseline CD4 cell count with survival time (Spearman p = 0.41; P = 0.002). However, no correlation was found between HIV RNA levels and survival time (P = 0.5).

CONCLUSIONS

In this population with very advanced disease, the HIV-1 RNA level was a poor discriminator of survival time, being inferior to the CD4 cell count and to specific clinical variables such as the nature of the prior AIDS-defining illness and the type of Pneumocystis carinii pneumonia prophylaxis employed. Among individuals with advanced AIDS, these data emphasize the relative importance of the CD4 cell count and of specific clinical factors, over the HIV-1 RNA level in predicting survival time.

Both serum HIV type 1 RNA levels and CD4+ lymphocyte counts predict clinical outcome in HIV type 1-infected subjects with 200 to 500 CD4+ cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team

To evaluate HIV-1 RNA and CD4+ cell responses to therapy as predictors of clinical progression and to evaluate levels and trends of these markers prior to clinical failure, HIV-1 RNA measurements were retrospectively obtained on subjects who progressed to AIDS or death and a random sample of subjects who did not. Samples were taken from AIDS Clinical Trials Group Study 175, a randomized trial comparing nucleoside analog therapies in subjects with CD4+ cell counts of between 200 and 500 cells/mm3. HIV-1 RNA and CD4+ cell count independently predicted clinical progression. Risk of subsequent progression is best captured by the change to the last measured value for CD4+ cell count and the area under the curve minus baseline, a measure of viral replication over time, for HIV-1 RNA. Subjects who failed had lower CD4+ cell counts, greater rates of CD4+ cell decline, and higher HIV-1 RNA levels, but not greater rates of HIV-1 RNA increase than subjects who did not. Subjects who maintained more than 200 CD4+ cells/mm3 and fewer than 10,000 copies of HIV-1 RNA per milliliter had low risk of progression. During the first few months of therapy, treatments are best monitored by regular HIV-1 RNA and less frequent CD4+ cell measurements. Thereafter, both markers should be monitored on a similar schedule to identify rapidly declining CD4+ cell counts, or adverse levels of either. These results further delineate the prognostic significance of HIV-1 RNA and CD4+ cell count and should help to better define their utility in the practice setting.

Elevated plasma levels of 90K (Mac-2 BP) immunostimulatory glycoprotein in HIV-1-infected children

90K is a secreted serum glycoprotein with immune stimulatory activity. In this study, 90K plasma levels were determined by an enzyme-linked immunosorbent assay in 18 HIV-1-infected children and 10 uninfected control children. 90K levels in HIV-1-infected children (median, 12.5 microg/ml) were higher than in HIV-1 uninfected control group (6.3 microg/ml; P < 0.05). 90K levels of HIV-1-infected children classified as stage B and C (median, 15.0 microg/ml and 22.7 microg/ml, respectively) were higher compared to children with stage A disease (median, 7.0 microg/ml; P < 0.05). A positive correlation (r = 0.5; P < 0.05) was found between 90K levels and HIV-1 RNA levels in 137 plasma samples of 18 HIV-1-infected children collected during a period of 1 year. No correlation was found between 90K levels and CD4 cell counts. These results suggest that 90K plasma levels may represent a novel marker of disease progression in HIV-1-infected children.

Time of initiation of antiretroviral therapy: impact on HIV-1 viraemia. The Swiss HIV Cohort Study

OBJECTIVE

The current recommendation that patients infected with HIV-1 be treated early is based on little evidence. We examined whether the early initiation of antiretroviral treatment affects residual HIV-1 viraemia.

METHODS

Viraemia was measured using an assay with a detection limit of 3 HIV-1 RNA copies/ml in drug-naive patients who started antiretroviral therapy at the time of primary HIV-1 infection (PHI) (n = 10), during chronic infection without immune suppression (CD4 cell counts > or = 500/mm3; median 577) (n = 10), or after immune suppression developed (CD4 cell counts < 500/mm3; median 113) (n = 21).

RESULTS

In 249 samples collected 24 to 120 weeks after treatment initiation, the mean proportion of samples with HIV-1 RNA levels of less than 3 copies/ml was 75% for PHI patients compared with 32 and 8% for immunocompetent and immunosuppressed chronically infected patients, respectively. Fifty per cent of PHI patients, but none of the chronically infected patients, had persistently fewer than 3 HIV-1 RNA copies/mL. PHI patients had lower residual HIV-1 RNA levels than chronically infected patients, and immunocompetent patients had lower residual HIV-1 RNA levels than immunosuppressed patients (all pairwise, P< 0.001). The mean residual HIV-1 RNA level was independently associated with the initiation of therapy during PHI and baseline CD4 cell counts (P < 0.001 for both associations).

CONCLUSION

Viraemia levels are associated with clinical progression and predict virological treatment failure. The initiation of antiretroviral therapy at the time of PHI and while CD4 cell counts are high results in lower residual viraemia. These results support early antiretroviral therapy in HIV-1-infected patients.

Regional survival differences across Europe in HIV-positive people: the EuroSIDA study

OBJECTIVES

To analyse the survival differences between macro-regions of Europe (northern, central and southern Europe) between 1994 and early 1999, and their possible association with antiretroviral treatment differences.

DESIGN

From September 1994 the EuroSIDA study has prospectively followed non-selected HIV-infected people from 50 clinical sites in 18 European countries (n = 7331).

METHODS

Cox proportional hazards models were used to compare death rates between regions and to investigate the relationship between treatment usage and regional mortality rates. Kaplan-Meier curves were used to compare survival from the first CD4 lymphocyte count of < 200 x 10(6)/l or < 50 x 10(6)/l.

RESULTS

At the time of analysis, the median follow-up was 21 months and there was a total of 1544 deaths. In people with a CD4+ cell count that fell below 200 or 50 x 10(6)/l those from central Europe had a better prognosis compared with those from the two other regions (P < 0.05). Patients from central Europe were more frequently exposed to reverse transcriptase inhibitors and protease inhibitors compared with patients from other regions (P < 0.001). There was a significant difference in risk of death between regions after adjustment for baseline differences in demography, presence of AIDS and level of immunodeficiency (risk of death in central Europe was 37% lower than that in southern Europe (P < 0.0001) and 33% lower than in northern Europe (P < 0.0001)). After adjustment for use of individual antiretroviral agents, intensity of treatment regimen, CD4 lymphocyte count, weight, haemoglobin and development of AIDS as time-dependent covariates, the differences became much smaller (risk in central Europe 13% lower than that in southern Europe (P = 0.071) and 15% lower than in northern Europe (P = 0.054).

CONCLUSION

Antiretroviral therapy has been used more aggressively in Europe in recent years, resulting in improved prognosis. In this study we observed that the HIV mortality rate in central Europe was significantly lower than those in northern and southern Europe in the period 1994 to early 1999. This finding appears to be due to the effect on survival of different treatment policies and drug availability in the three regions of Europe during this time period, with central European countries, on average, having introduced more aggressive treatment strategies earlier.

Estimating AIDS-free survival in a severely immunosuppressed asymptomatic HIV-infected population in the era of antiretroviral triple combination therapy. Swiss HIV Cohort Study

BACKGROUND

Antiretroviral triple combination therapies have been evaluated in randomized controlled trials and cohort studies. Little is known about their impact on asymptomatic, severely immunosuppressed, HIV-infected individuals in a real world population.

OBJECTIVES

To describe disease progression in a broad asymptomatic population of HIV-infected individuals with a CD4 count <100 cells/mm3 before and after the introduction of combination triple therapy.

DESIGN

Six-month homogenous Markov chain consisting of four recurrent AIDS-free states and one absorbing AIDS state: (1) CD4 count > or =100 cells/mm3, (2) CD4 count 75 to 99 cells/mm3, (3) CD4 count 50 to 74 cells/mm3, (4) CD4 count 0 to 49 cells/mm3, and AIDS.

SETTING

Swiss HIV Cohort Study database.

PATIENTS

A total of 1027 patients contributed to 2634 pairs of 6-month observations from 1993 to 1995, and 681 patients contributed to 2077 pairs of 6-month observations from 1996 to 1997.

MEASUREMENT

AIDS-free survival probabilities and the expected AIDS-free survival time.

RESULTS

The expected number of AIDS-free months in a 3-year period was 17 (95% confidence interval [CI], 16-19) for patients starting in state 4 prior to 1996 versus 26 months (95% CI, 24-28) for patients starting in state 4 after 1996. For these two time periods, the corresponding expected numbers of AIDS-free months were 21 (95% CI, 20-22) versus 30 (95% CI, 28-32) for state 3 and 23 (95% CI, 21-24) versus 33 (95% CI, 32-34) for state 2.

CONCLUSION

Expected 3-year AIDS-free survival in severely immunosuppressed individuals with CD4 counts <100 cells/mm3 improved significantly between 1993 to 1995 and 1996 to 1997.

CD4+ and CD8+ lymphocytes and HIV RNA in HIV infection: high baseline counts and in particular rapid decrease of CD8+ lymphocytes predict AIDS

OBJECTIVE

To study the progression of HIV infection in relation to immunological and virological variables with emphasis on the role of CD8+ lymphocytes.

DESIGN

Prospective follow-up from October 1991 of patients observed for at least 18 months allowing nucleoside analogue monotherapy. Peripheral CD4+ and CD8+ lymphocyte counts, HIV RNA, and soluble CD8 were analysed by statistics allowing the evaluation of serial data, avoiding time points with concurrent infections.

SETTING

Tertiary university clinic.

PATIENTS

Forty-nine patients were followed for 52.6 months, baseline CD4+ count of 300 x 10(6)/l, sample interval of 5.9 months (medians).

MAIN OUTCOME MEASURES

AIDS, death, and CDC groups B- or C-related events.

RESULTS

AIDS developed in 28% of patients. Baseline CD8+ counts above the median were significantly associated with AIDS development; the best Cox model included CD8+ cells and the log10RNA/CD4 ratio. A decline in CD8+ counts relative to baseline most significantly predicted AIDS, along with higher baseline RNA and actual CD4+ counts of less than 200 x 10(6)/l. Levels of soluble CD8 in the blood relative to total CD8+ cells significantly increased in patients developing AIDS. Death occurred in 16% of the patients, and was only predicted by high CD8+ cell counts at baseline. CDC B- and C-related events occurred in 35% of the patients and were best predicted by high baseline CD8+ counts and high RNA levels.

CONCLUSIONS

The serial quantitation of CD8+ lymphocytes gave highly significant predictive information on the natural progression of HIV infection in patients with moderate to severe immune deficiency. Our data suggest that the hyperactivation of CD8+ lymphocytes is an important factor leading to a numerical decrease of CD8+ lymphocytes in progressive HIV infection.

HIV-1 RNA response to antiretroviral treatment in 1280 participants in the Delta Trial: an extended virology study

OBJECTIVE

To assess changes in HIV RNA and their relationship to disease progression.

DESIGN AND SETTING

Delta was a randomized double-blind trial comparing zidovudine (ZDV) monotherapy with ZDV plus didanosine (ddI) or ZDV plus zalcitabine (ddC). Participants had AIDS (with CD4 cell counts above 50 x 10(6)/l), AIDS-related complex, or were asymptomatic with CD4 cell counts below 350 x 10(6)/l. The trial included both ZDV-naive and ZDV-experienced participants.

PARTICIPANTS

A total of 1280 participants in the Delta trial whose serum samples had been stored at -70 degrees C and who had a minimum of one sample taken before the start of treatment and at least one later sample.

METHODS

HIV-1 RNA quantification was performed using the nucleic acid sequence-based amplification HIV-1 RNA quantitative assay with a cut-off of 800 copies/ml.

RESULTS

Reductions in HIV RNA by treatment group were consistent with the clinical results; in ZDV-naive participants the maximum median fall occurred at 4 weeks for all three groups (ZDV, 0.54 log10 copies/ml; ZDV-ddI, 1.38 log10 copies/ml; ZDV-ddC, 1.31 log10 copies/ml). On average the reductions were smaller in ZDV-experienced participants but the difference between the monotherapy and combination arms was very similar in ZDV-naive and experienced participants. Baseline HIV RNA levels, adjusted for CD4 cell counts were highly predictive of time to virological response (HIV RNA < 800 copies/ml); HIV RNA nadirs achieved were predictive of survival. Viral load rebound following response was independent of treatment group and previous ZDV therapy.

CONCLUSIONS

Virological changes in response to treatment are of value in assessing prognosis and the activity of new therapies; in particular, there is a strong association between the minimum HIV RNA achieved in the first 16 weeks and subsequent clinical response. CD4 cell counts are independently predictive of response.

A randomized, controlled, double-blind study comparing the survival benefit of four different reverse transcriptase inhibitor therapies (three-drug, two-drug, and alternating drug) for the treatment of advanced AIDS. AIDS Clinical Trial Group 193A Study Team

OBJECTIVE

The primary objective was to compare the effects of dual or triple combinations of HIV-1 reverse transcriptase inhibitors with respect to survival. The time to new HIV disease progression or death, toxicities, the change in CD4 cells, and plasma HIV-1 RNA concentrations in a subset of study subjects were evaluated.

DESIGN

This was a multicenter randomized, double-blind, placebo-controlled study.

SETTING

The study was conducted among 42 adult AIDS Clinical Trials Group sites and 7 National Hemophilia Foundation centers.

PATIENTS

1313 HIV-infected patients with CD4 counts < or = 50 cells/mm3 participated in this study, which was conducted from June 1993 to June 1996.

INTERVENTION

Patients were randomized to one of four daily regimens containing 600 mg of zidovudine: zidovudine alternating monthly with 400 mg didanosine; zidovudine plus 2.25 mg of zalcitabine; zidovudine plus 400 mg of didanosine; or zidovudine plus 400 mg of didanosine plus 400 mg of nevirapine (triple therapy).

MAIN OUTCOME MEASURES

The main outcome was survival (i.e., time to death).

RESULTS

A significant difference in survival time was found between the four treatment groups, favoring those assigned to triple therapy (p = .02). A significant difference was also found in the delay of disease progression or death among the four treatment arms favoring the group assigned to triple therapy (p = .002). Baseline CD4 cell counts and plasma HIV-1 RNA concentrations as well as changes of CD4 counts at week 8 predicted survival for subjects in the virology substudy.

CONCLUSIONS

In the pre-protease inhibitor era, a combination of triple reverse transcriptase inhibitors prolonged life and delayed disease progression in AIDS patients with advanced immune suppression.

Predictors of a viral response and subsequent virological treatment failure in patients with HIV starting a protease inhibitor

OBJECTIVES

To investigate the factors related to viral load becoming undetectable among patients from Southern Alberta who started a protease inhibitor for the first time, and to determine the factors related to subsequent re-emergence of detectable viral load amongst those patients whose viral load initially became undetectable.

SUBJECTS AND METHODS

A total of 243 patients from the Southern Alberta Clinic had started a protease inhibitor for the first time and had been followed up for a median time of 32 weeks. Standard survival techniques including Kaplan-Meier techniques and Cox proportional hazards models were used to determine which factors were related to viral load becoming undetectable.

RESULTS

At 24 weeks after first exposure to a protease inhibitor, 52.8% of the patients [95% confidence interval (Cl), 45.2-56.6] had achieved an undetectable viral load. In a multivariate analysis, those with a higher initial viral load were less likely to become undetectable [relative hazard (RH), 0.50; 95% Cl, 0.35-0.70; P < 0.0001], whereas those starting more new drugs (RH per new drug, 1.54; 95% Cl, 1.01-2.11; P = 0.048) were significantly more likely to achieve an undetectable viral load. Amongst 111 patients whose viral load became undetectable, Kaplan-Meier analysis indicated that 15.5% of patients experienced re-emergence of detectable viral load at 24 weeks after the first undetectable viral load. A higher CD4 cell count was associated with a lower risk of viral load becoming detectable (RH, 0.73; 95% Cl, 0.53-1.00; P = 0.049), as was treatment with indinavir (versus any other protease inhibitor RH, 0.17; 95% Cl, 0.03-0.86; P = 0.033).

CONCLUSIONS

A significant proportion of patients in a routine clinic setting achieved an undetectable viral load measurement after first starting a protease inhibitor; viral load in patients with a higher CD4 cell count was more likely to become and stay undetectable. There was no evidence that patients who were drug-naive experienced significantly worse virological effects than drug-experienced patients, as long as the same number of new drugs was started at the date of first exposure to a protease inhibitor. Further follow-up of these patients is warranted to study the longer term effects of treatment with protease inhibitors.

Transforming laboratory test results to improve clinical outcome predictions in HIV patients. Swiss HIV Cohort Study

Transforming natural units of laboratory markers of HIV disease may improve their ability to predict clinical outcomes. The authors examined this issue within a prospective study of 394 patients enrolled in the Swiss HIV Cohort Study (SHCS) between 1991 and 1993. Baseline predictors included CD4+ and CD8+ cell counts, HIV RNA levels, beta2-microglobulin, and age. Outcomes were death and clinical progression. A range of power transformations was applied to each predictor, and the goodness-of-fit of the corresponding proportional hazards models was assessed. The prognostic value of all laboratory variables could be improved on by power transformations. To predict either outcome variable, the "best" transformation of HIV RNA copies and CD8+ cell counts was the logarithm; for beta2-microglobulin, it was power -2. For CD4+ cell counts, the best transformation depended on the outcome variable: it was power 0.2 when predicting survival, and power 0.4 when predicting clinical progression. The single best predictor variable was the ratio of HIV RNA copies per CD4+ cell, for both death (logarithmic transformation) and clinical progression (power -0.1 transformation). Natural units of laboratory variables are not optimal for the prediction of clinical events in HIV-infected patients. Which transformation is best depends on the predictor under consideration.