Determinants of progression of HIV infection in a Greek hemophilia cohort followed for up to 16 years after seroconversion

Effect of tuberculosis preventive therapy on HIV disease progression and survival in HIV-infected adults

PURPOSE

To determine whether tuberculosis (TB) preventive therapies alter the rate of disease progression to AIDS or death and to identify significant prognostic factors for HIV disease progression to AIDS.

METHOD

In a randomized placebo-controlled trial in Kampala, Uganda, 2,736 purified protein derivative (PPD)-positive and anergic HIV-infected adults were randomly assigned to four and two regimens, respectively. PPD-positive patients were treated with isoniazid (INH) for 6 months (6H; n = 536), INH plus rifampicin for 3 months (3HR; n = 556), INH plus rifampicin plus pyrazinamide for 3 months (3HRZ; n = 462), or placebo for 6 months (n = 464). Anergic participants were treated with 6H (n = 395) or placebo (n = 323).

RESULTS

During follow-up, 404 cases progressed to AIDS and 577 deaths occurred. The cumulative incidence of the AIDS progression was greater in the anergic cohort compared to the PPD-positive cohort (p < .0001). Among PPD-positive patients, the relative risk of the AIDS progression with INH alone was 0.95 (95% CI 0.68-1.32); with 3HR it was 0.83 (95% CI 0.59-1.17); and with 3HRZ it was 0.76 (95% CI 0.52-1.08), controlling for significant baseline predictors. Among anergic patients, the relative risk of the AIDS progression was 0.81 (95% CI 0.56-1.15). Survival was greater in the PPD-positive cohort compared to the anergic cohort (p = .0001).

CONCLUSION

The number of signs or symptoms at baseline and anergic status are associated with increasing morbidity and mortality. Even though the tuberculosis preventive therapies were effective in reducing the incidence of TB for HIV-infected adults, their benefit of delaying HIV disease progression to AIDS was not observed.

Trends in AIDS and Mortality in HIV-Infected Subjects With Hemophilia From 1985 to 2003

OBJECTIVE

To study trends in progression to AIDS, all-cause mortality, and cause-specific mortality (AIDS-related, liver disease, and hemorrhagic complications) over calendar periods with different exposure to highly active antiretroviral therapy (HAART) in a cohort of hemophiliacs in Spain, taking into account the competing risks of the causes of death.

METHODS

Multicenter cohort of HIV-infected hemophiliacs. HIV seroconversion was estimated using mathematic techniques for interval-censored data from 1979 through 1985. Rates of AIDS and cause-specific death were calculated by Poisson regression, allowing for late entry, for the periods 1985 through 1992, 1993 through 1996, 1997 through 2000 (early HAART), and 2001 through 2003 (late HAART), also allowing for competing risks.

RESULTS

Of 585 subjects, 44% were younger than 15 years of age, 82% had severe hemophilia, 86% had type A hemophilia, and the median seroconversion date was October 1982. Calendar period and age at HIV seroconversion strongly influenced AIDS and death rates. Compared with 1993 through 1996, decreases of 75% (relative risk [RR] = 0.25, 95% confidence interval [CI]: 0.14 to 0.43) and 72% (RR = 0.28, 95% CI: 0.12 to 0.63) in the RR of AIDS were observed in early and late HAART. For all-cause mortality, 72% (RR = 0.28, 95% CI: 0.18 to 0.42) and 83% (RR = 0.17, 95% CI: 0.09 to 0.33) decreases were observed by 1997 through 2000 and 2001 through 2003. For liver-related deaths, increases were observed in the late-HAART period (RR = 2.80, 95% CI: 0.94 to 8.36) compared with 1993 through 1996, but using competing risks, this RR was substantially reduced (RR = 1.70, 95% CI: 0.57 to 5.04).

DISCUSSION

Major reductions in AIDS and death rates were observed from 1997 to 2003 in hemophiliacs. These survival improvements are largely attributable to decreases in AIDS-related deaths and have been accompanied by increases in liver disease death rates, which are overestimated if competing risks are not taken into account.

Progression of HIV infection in the post-HAART era among a cohort of HIV+ Greek haemophilia patients

AIM

The study aims to describe the course of HIV-1 infection in the pre- and post-HAART period in a cohort of HIV+ haemophilia patients followed up for up to 21 years.

METHODS

The cohort includes 158 haemophilic men with known seroconversion dates followed up prospectively for a median time of 12 and 5.7 years in the pre- (1980-96) and post-HAART period (1997-2003), respectively.

RESULTS

The risk of developing AIDS was lowered by 56% in the post- as compared to the pre-HAART period. Of the 158 patients 69 developed AIDS in the pre-HAART period while of the 59 subjects still alive and AIDS free on 1/1/1997 six developed AIDS. The rate of PCP (12.0 cases per 1000 person-years) and NHL (5.4 cases per 1000 person-years), the most common causes of AIDS diagnosis in the pre-HAART era, were remarkably reduced in the post-HAART era (both rates: 2.8 cases per 1000 person-years). On the contrary, the corresponding risk for non-AIDS deaths was fourfold increased in the post-HAART period. Of the 38 non-AIDS related deaths in both periods, 13 occurred post-HAART. The predominant cause of non-AIDS mortality in both periods was end-stage liver disease (ESLD) (7 pre- and 4 post-HAART). The rate of non-AIDS related cancers was also increased during the post-HAART period.

CONCLUSION

In this haemophilia cohort the risk of AIDS has substantially reduced in the post-HAART period, but the rate of non-AIDS mortality tended to increase. Among haemophilia subjects, due to the high rates of HCV/HIV coinfection, ESLD, the predominant cause of non-AIDS mortality, will become an increasingly important clinical problem.

HLA antigens as predictors of disease progression in HIV-infected haemophilia patients (a 22 years' follow up)

Our objective was to assess the influence of genetic factors such as HLA classes I and II antigens and other clinical and laboratory variables on the progression of HIV disease in a cohort of 118 HIV infected haemophilic subjects of Greek origin who had been typed for HLA antigens and were followed up prospectively for 22 years since seroconversion. At the end of the follow up we compared two groups of patients: 22 patients who had a fast progression to AIDS (median 6 years since seroconversion) vs. 33 patients who remained asymptomatic in stage A2 for up to 22 years (median 15 years). The results showed that the two groups did not differ significantly in age at seroconversion or baseline CD4+ T cell count. However there was a difference in the frequencies of certain HLA antigens in the two groups. The fast progressors had a higher frequency of HLA-A28, B21 and DR3, which was statistically significant (P = 0.02, 0.04, 0.05, respectively) compared to the slow progressors. These findings based on classical HLA typing techniques confirm other published observations and support the effect of genetic background in the progression of HIV infection in haemophilics.

Cellular HIV-1 DNA load predicts HIV-RNA rebound and the outcome of highly active antiretroviral therapy

OBJECTIVE

To assess whether cellular HIV-1 DNA prior to highly active antiretroviral therapy (HAART) initiation predicts its outcome.

DESIGN AND METHODS

Patients included all 51 hemophiliacs of the Greek component of the Multicenter Hemophilia Cohort Study who had initiated HAART and for whom cryopreserved lymphocyte samples before HAART initiation were available. Cellular HIV-1 DNA quantification was performed by a molecular beacon-based real-time PCR assay in multiple samples per patient with a median (interquartile range) follow-up of 76 (45-102) weeks.

RESULTS

The median (range) baseline HIV-1 DNA load was 297 (< 10 to 3468) copies per 1 x 10(6) peripheral blood mononuclear cells. Baseline HIV-1 DNA load did not predict initial virological response (VR). None of the patients with initial VR and baseline HIV-1 DNA load at or below the median experienced a subsequent virological rebound, while the cumulative probability of virological rebound by week 104 was 55% among those with HIV-1 DNA load greater than the median (P < 0.008). Cellular HIV-1 DNA load was the only parameter associated with sustained virological response as shown by univariate or multivariate analyses [adjusted odds ratio (95% confidence interval) 0.197 (0.048-0.801) per 1 log10 increase in DNA copies, P = 0.023].

CONCLUSION

Low cellular HIV-1 DNA load is a marker of sustained virological response in patients with initial VR and it can reliably predict the long-term success of HAART.

Importance of cytomegalovirus viraemia in risk of disease progression and death in HIV-infected patients receiving highly active antiretroviral therapy

BACKGROUND

Before highly active antiretroviral therapy (HAART) became available, cytomegalovirus was a major cause of opportunistic infection in HIV-infected patients and was associated with accelerated progression to AIDS and death. We have investigated whether cytomegalovirus viraemia remains a significant risk factor for progression of HIV disease and death in the era of HAART.

METHODS

374 patients whose CD4-cell count had ever been below 100 per microL were enrolled in a prospective study. Serial blood samples were tested for cytomegalovirus by PCR. Rates of new cytomegalovirus disease, new AIDS-defining disorders, and death were calculated over a median follow-up of 37 months after stratification according to baseline and most recent cytomegalovirus PCR status at any point during follow-up.

FINDINGS

Of 2969 PCR assays, 375 (12.6%) were positive for cytomegalovirus DNA. 259 (69.3%) patients were persistently negative for cytomegalovirus by PCR; 15 were persistently positive; and 100 were intermittently positive and negative. In multivariate models, cytomegalovirus PCR-positive status as a time-updated covariate was significantly associated with increased relative rates of progression to a new AIDS-defining disorder (2.22 [95% CI 1.27-3.88] p=0.005) and death (4.14 [1.97-8.70] p=0.0002).

INTERPRETATION

Detection of cytomegalovirus in blood by PCR continues to identify patients with a poor prognosis, even in the era of HAART. Randomised controlled clinical trials of drugs active against cytomegalovirus are needed to investigate whether this virus is a marker or a determinant of HIV disease progression.

Changes in T cell receptor excision DNA circle (TREC) levels in HIV type 1-infected subjects pre- and post-highly active antiretroviral therapy

The T cell receptor excision DNA circle (TREC) level is an independent predictor of HIV-1 disease prognosis. We studied the temporal changes in TREC levels prior to and after highly active antiretroviral therapy (HAART) in a cohort of 131 Greek men with hemophilia who were followed up for up to 20 years since seroconversion (SC). TREC levels were determined in all available cryopreserved samples of peripheral blood mononuclear cells (PBMCs) using a multiplex real-time polymerase chain reaction (PCR) assay. Trends in log(10) TREC values were described using random effects models. Prior to HAART initiation TREC levels tended to decrease over time (mean rate of drop 19% per year; 95% CI: 16-22%). Initial TREC values were higher with younger age at SC, but the subsequent rate of drop did not differ significantly by age at SC. There was a monotonic relationship between baseline HIV-RNA levels and TREC slopes with steeper slopes at higher levels of HIV-RNA. The TREC slopes differed significantly by clinical outcome being steeper in subjects who progressed to AIDS sooner. After HAART initiation, TREC values tended to increase on average by 35% per year (95% CI: -7-94%) but the increase was evident only in subjects with a pre-HAART CD4 count below 80 cells/microl. TREC values, which likely represent a simple indicator of naive T-lymphocyte reserve, may be a clinically useful marker for long-term prognosis of HIV-1 infection and for immune reconstitution after successful HAART.

Quantitation of human immunodeficiency virus type 1 DNA forms with the second template switch in peripheral blood cells predicts disease progression independently of plasma RNA load

There are several forms of human immunodeficiency virus type 1 (HIV-1) DNA in peripheral blood T cells and lymph nodes in untreated HIV-1-infected individuals and in patients whose plasma HIV-1 RNA levels are suppressed by long-term combination antiretroviral therapy. However, it remains to be established whether the concentration of HIV-1 DNA in cells predicts the clinical outcome of HIV-1 infection. In this report, we measured the concentration of HIV-1 DNA forms which has undergone the second template switch (STS DNA) and 2-long-terminal-repeat DNA circles in peripheral blood mononuclear cell (PBMC) samples. To do this, we used molecular-beacon-based real-time PCR assays and studied 130 patients with hemophilia in the Multicenter Hemophilia Cohort Study. We assessed the influence of baseline HIV-1 STS DNA levels on the progression of HIV-1 disease in the absence of combination antiretroviral therapy by Kaplan-Meier and Cox regression analysis. Among the patients who progressed to AIDS, the median levels (interquartile ranges) of STS HIV-1 DNA in PBMC were significantly higher than those of patients who remained AIDS free during the 16 years of follow-up (1,017 [235 to 6,059] and 286 [31 to 732] copies per 10(6) PBMC, respectively; P < 0.0001). Rates of progression to death and development of AIDS varied significantly (log rank P < 0.001) by quartile distribution of HIV-1 STS DNA levels. After adjustment for age at seroconversion, baseline CD4(+) T-cell counts, plasma viral load, and T-cell-receptor excision circles, the relative hazards (RH) of death and AIDS were significantly increased with higher HIV-1 STS DNA levels (adjusted RH, 1.84 [95% confidence interval (CI), 1.30 to 2.59] and 2.62 [95% CI, 1.75 to 3.93] per 10-fold increase per 10(6) PBMC, respectively). HIV-1 STS DNA levels in each individual remained steady in longitudinal PBMC samples during 16 years of follow-up. Our findings show that the concentration of HIV-1 STS DNA in PBMC complements the HIV-1 RNA load in plasma in predicting the clinical outcome of HIV-1 disease. This parameter may have important implications for understanding the virological response to combination antiretroviral therapy.

Significance of immune status, genotype and viral load in the severity of chronic hepatitis C in HIV infected haemophilia patients

Chronic hepatitis C is associated with more severe liver disease in patients coinfected with HIV, but the pathogenic mechanism of this more aggressive course is still unclear. The aim of this study was to assess the relationship of HCV genotype, viral load and epidemiological factors with the histological severity of chronic hepatitis in haemophilia patients with HCV/HIV coinfection, taking into consideration the immune status of the patients. Twenty-one HIV/HCV coinfected haemophilia patients, with mean age +/- SD 35.7 +/- 8.7 years, underwent transcutaneous liver biopsy 6-15 years (median 12 years) after HIV and 6-32 (median 21.5 years) years after HCV infection. Twelve patients were stage A (CDC), six stage B and three stage C. CD4 cells were < 50 microL(-1) in three patients (14.3%), 50-200 in 11(52.4%) and > 200 in 7(33.3%). Mean +/- SD log(10) HCV-RNA was 6.87 +/- 0.7 copies mL(-1) (range 5.4-7.9), and mean +/- SD log(10) HIV-RNA was 3.75 +/- 0.98 copies mL(-1) (range 2.7-6), at the time of liver biopsy. Minimal hepatitis was diagnosed in five patients (24%), mild in 10 (48%) and moderate in six (28%). Hepatitis stage 0-2 was found in seven cases (33%) and cirrhosis in six (29%). Statistical analysis showed a significant association of CD4 count < 50 with minimal hepatitis and of CD > 200 with mild and moderate hepatitis (P = 0.033). In addition, minimal hepatitis was found only in patients with stage C, while the majority of subjects with HIV stage A showed mild and moderate hepatitis (P = 0.003). Moreover genotype 1 was independently associated with advanced hepatitis stage (P = 0.04). No relationship was found between hepatitis severity, HIV or HCV RNA levels, patient's age and duration of HIV or HCV infection. Our results suggest that HCV/HIV coinfection may aggravate the course of hepatitis in the phase of immunocompetence, most probably through an immune mediated process. Genotype 1 seems to be associated with advanced liver disease.

Impact of missing data due to selective dropouts in cohort studies and clinical trials

BACKGROUND

Many cohort studies and clinical trials use repeated measurements of laboratory markers to track disease progression and to evaluate new therapies. A major problem in the analysis of such studies is that marker data are censored in some patients owing to withdrawal, loss to follow-up, or death. The objective of this paper is to evaluate the impact of selective dropouts attributable to death or disease progression on the estimates of marker change among different groups.

METHODS

Data on CD4 cell count in human immunodeficiency virus 1-infected individuals from a clinical trial and a cohort study are used to illustrate this problem and a possible solution. Simulation studies are also presented.

RESULTS

When the rate of dropout is greater in subjects whose marker status is declining rapidly, commonly used methods, like random effects models, that ignore informative dropouts lead to overoptimistic statements about the marker trends in all compared groups, because subjects with steeper marker drops tend to have shorter follow-up times and hence are weighted less in the estimation of the group rate of the average marker decline.

CONCLUSIONS

The potential biases attributable to incomplete data require greater recognition in longitudinal studies. Sensitivity analyses to assess the effect of dropouts are important.

Impact of missing data due to drop-outs on estimators for rates of change in longitudinal studies: a simulation study

Many cohort studies and clinical trials are designed to compare rates of change over time in one or more disease markers in several groups. One major problem in such longitudinal studies is missing data due to patient drop-out. The bias and efficiency of six different methods to estimate rates of changes in longitudinal studies with incomplete observations were compared: generalized estimating equation estimates (GEE) proposed by Liang and Zeger (1986); unweighted average of ordinary least squares (OLSE) of individual rates of change (UWLS); weighted average of OLSE (WLS); conditional linear model estimates (CLE), a covariate type estimates proposed by Wu and Bailey (1989); random effect (RE), and joint multivariate RE (JMRE) estimates. The latter method combines a linear RE model for the underlying pattern of the marker with a log-normal survival model for informative drop-out process. The performance of these methods in the presence of missing data completely at random (MCAR), at random (MAR) and non-ignorable (NIM) were compared in simulation studies. Data for the disease marker were generated under the linear random effects model with parameter values derived from realistic examples in HIV infection. Rates of drop-out, assumed to increase over time, were allowed to be independent of marker values or to depend either only on previous marker values or on both previous and current marker values. Under MACR all six methods yielded unbiased estimates of both group mean rates and between-group difference. However, the cross-sectional view of the data in the GEE method resulted in seriously biased estimates under MAR and NIM drop-out process. The bias in the estimates ranged from 30 per cent to 50 per cent. The degree of bias in the GEE estimates increases with the severity of non-randomness and with the proportion of MAR data. Under MCAR and MAR all the other five methods performed relatively well. RE and JMRE estimates were more efficient(that is, had smaller variance) than UWLS, WLS and CL estimates. Under NIM, WLS and particularly RE estimates tended to underestimate the average rate of marker change (bias approximately 10 per cent). Under NIM, UWLS, CL and JMRE performed better in terms of bias (3-5 per cent) with the JMRE giving the most efficient estimates. Given that markers are key variables related to disease progression, missing marker data are likely to be at least MAR. Thus, the GEE method may not be appropriate for analysing such longitudinal marker data. The potential biases due to incomplete data require greater recognition in reports of longitudinal studies. Sensitivity analyses to assess the effect of drop-outs on inferences about the target parameters are important.

Comparison of smoothing techniques for CD4 data in a Markov model with states defined by CD4: an example on the estimation of the HIV incubation time distribution

Multi-state models defined in terms of CD4 counts are useful for modelling HIV disease progression. A Markov model with six progressive CD4-based states and an absorbing state (AIDS) was used to estimate the cumulative probability of progressing to AIDS in 158 HIV-1 infected haemophiliacs with known seroconversion (SC) dates. A problem arising in such analysis is how to define CD4-based states, since this marker is subject to measurement error and short timescale variability. Four approaches were used: no smoothing, ad hoc smoothing (to move to a later/previous state two consecutive measurements to later/previous states are needed), kernel smoothing and random effects (RE) models. The estimates were compared with the Kaplan-Meier estimate based solely on data concerning time to AIDS. There was an apparent lack of agreement between the Kaplan-Meier and the "no smoothing" estimate. With the exception of the "no smoothing" method, "ad hoc", kernel and RE estimates fell within the range of the 95 per cent CIs of the Kaplan-Meier curve. Simulations demonstrated that the use of raw CD4 counts provides overestimated transition intensities. Compared to the kernel method, ad hoc is easier to implement and overcomes the problem of the choice of bandwidth. The RE approach leads to simple models, since it usually results in very few transitions to previous states, and can handle individuals with sparse data by smoothing their predictions towards the population mean. Ad hoc was the method that performed better, in terms of bias, than the other smoothing approaches.

Predicting HIV disease progression in children using measures of neuropsychological and neurological functioning. Pediatric AIDS clinical trials 152 study team

BACKGROUND

Neuropsychological testing and 2 measures of neurological status, cortical atrophy, and motor dysfunction were assessed for their usefulness in predicting human immunodeficiency virus (HIV) disease progression in infants, children, and adolescents who participated in Pediatric AIDS Clinical Trials Group Protocol 152 (PACTG 152).

METHODS

A cohort of 722 antiretroviral therapy-naive children with symptomatic HIV infection were assessed at study entry and at later intervals. Assessments included neurodevelopmental testing, neuroradiologic imaging, and neurological examination of motor function. CD4 cell count and plasma RNA viral load also were measured.

RESULTS

Children with the lowest neuropsychological functioning (IQ < 70) at baseline had the highest risk for later HIV disease progression (56%), compared with those with borderline/low (IQ = 70-89) functioning (26%), or with average or above (IQ > 90) functioning (18%). This was also true of week 48 neuropsychological functioning. Motor dysfunction (especially reduced muscle mass) at entry also predicted disease progression. Furthermore, motor dysfunction and week 48 neuropsychological functioning provided predictive information beyond that obtainable from surrogate markers of HIV disease status (eg, CD4 count, HIV RNA level). Children with cortical atrophy also were at higher risk for later disease progression, but when CD4 count and RNA viral load were known, cortical atrophy information provided no additional predictive information.

CONCLUSIONS

Measures of neuropsychological and motor function status provide unique information regarding pediatric HIV disease progression. As such, these findings have important implications for predicting long-term outcomes (eg, longevity) in pediatric patients.

Effect of ignoring the time of HIV seroconversion in estimating changes in survival over calendar time in observational studies: results from CASCADE

OBJECTIVE

To compare estimates of changes in HIV survival over time derived from seroconverter and prevalent cohorts.

DESIGN AND METHODS

Using pooled data from 19 seroconverter cohorts (CASCADE), the relative risk of death from HIV seroconversion by calendar time at risk from 1 January 1991 was examined. The analyses were repeated, ignoring knowledge of the time of seroconversion, but adjusting for the CD4 cell count at the time the participant came under observation, thus mimicking a prevalent cohort. Estimates from the 'prevalent' cohort approach were compared with those obtained from the seroconverter cohort.

RESULTS

Of 5428 subjects at risk on 1 January 1991 or later, 1312 (24.2%) had died. In the analysis based on time from seroconversion, estimates of the effect of calendar year showed marked reductions in mortality in 1997-1999 only, with no evidence of a linear trend over the period 1991-1996 (P-trend = 0.85). Using the prevalent cohort approach a decrease in the relative risk of death was observed from 1991 to 1998-1999, with a statistically significant trend of a decrease in risk from 1991 to 1996 (P-trend = 0.002). Similar findings were observed when the analyses was repeated taking the start date of the cohort as 1 January 1988.

CONCLUSION

Lack of knowledge of HIV infection duration may lead to biased and exaggerated estimates of survival improvements over time. The adjustment for duration of infection in prevalent HIV cohorts through laboratory markers may compensate inadequately for this.

Hepatitis C virus co-infection is a negative prognostic factor for clinical evolution in human immunodeficiency virus-positive patients

A longitudinal study of human immunodeficiency virus (HIV)-infected individuals followed-up in 13 centres was performed to assess the influence of hepatitis C virus (HCV) on the clinical and immunological evolution of HIV-infected patients. Eight-hundred and twelve HIV-infected patients with known HIV acquisition date, 89 co-infected with HCV, were included in the cohort. Clinical progression was defined as: 30% decrease of Karnofsky's index; and/or 20% body weight loss; and/or acquired immune deficiency syndrome (AIDS)-defining illness; and/or death (except by accident, suicide, or overdose). Immunological progression was defined as a decrease of initial CD4 count to below 200 mm(-3). If immunological progression was not statistically different between groups (P=0.25), clinical progression was significantly faster in HCV-HIV co-infected patients in univariate (P=0.02) and multivariable survival analysis (hazard ratio=1.63, P=0.03). This argues for active management of hepatitis C chronic infection among HCV-HIV co-infected patients.

Effect of recent thymic emigrants on progression of HIV-1 disease

BACKGROUND

The concentration of T-cell receptor-rearrangement excision DNA circles (TREC) in peripheral-blood T cells is a marker of recent thymic emigrant alphabeta T cells. We studied the predictive ability of measurements of TREC for clinical outcome in HIV-1-infected individuals.

METHODS

We measured TREC in peripheral-blood mononuclear cells with a real-time PCR assay. We studied 131 Greek participants in the Multicenter Hemophilia Cohort Study who had known HIV-1 seroconversion dates. The prognostic value of baseline TREC, CD4 T-cell count, and HIV-1 RNA concentration was assessed by Kaplan-Meier and Cox's regression analysis.

FINDINGS

Four participants had progressed to AIDS by first blood sampling. Among the remaining 127 individuals, the median value of TREC per 10(6) cells was 6900 (IQR 2370-15604). Baseline TREC values were lower in the 53 who progressed to AIDS than in those who did not (geometric mean 2843 [95% CI 1468-5504] vs 6560 [4723-9113] per 10(6) cells; p=0.017). The relative hazard of AIDS, adjusted for plasma viral load, CD4 T-cell count, and age at seroconversion was 1.44 (95% CI 1.04-2.01; p=0.031) per ten-fold increase in TREC; that for death was 1.52 (1.12-2.06; p=0.007). The adjusted relative hazards of death were 2.91 (1.91-4.44; p<0.001) per ten-fold increase in plasma HIV-1 RNA load and 1.20 (1.04-1.38; p=0.014) per 100-cell decrease in CD4 T-cell count.

INTERPRETATION

The concentration of TREC in the peripheral T-cell pool complements HIV-1 RNA load and CD4 T-cell count in predicting the rate of HIV-1 disease progression. Recent thymic emigrants have a role in the pathogenesis of HIV-1 disease.