Category of exposure to HIV and age in the progression to AIDS: longitudinal study of 1199 people with known dates of seroconversion. HIV Italian Seroconversion Study Group

Relationship between HIV-1 viral load and continued drug use in untreated infected injection drug users

The role of continued drug use in development of AIDS has been investigated, using mainly CD4(+) cells as outcome variable. The objective of this study was to verify whether continued drug use can influence HIV-1 plasma viral load.We used cross-sectional enrolment data of the HIV-infected IDUs cohort study Manif 2000 (October 1995-October 1996), recruiting patients in hospital departments of Marseilles, Nice and Paris suburbs. To minimize biases due to differential access to health care, only patients receiving outpatient care for at least 2 years but with no antiretroviral treatment were selected for analysis (n = 108). Available information regarding clinical and laboratory information from medical records and clinical examination as well as drug use and HIV-related risk practices were obtained by a face-to-face and a self-administered questionnaire. Patients denying recent heroin injection were cross-validated by a serological assay to detect morphine. Forty-two patients (39%) reported recent heroin injection; among those denying recent use (n=66), eight (positive for serum morphine assay) were re-classified as IDUs. A difference of 0.35 log in viral load was observed between active and ex-IDUs which increases (0.6 log, p=0.03) in those who have been using drugs for 10 years or more.This result persisted when adjusted for CD4(+) counts, clinical stage or years since diagnosis. Continued drug use may have a significant but limited impact on HIV viral load only in patients with a longer history of drug use. Consequences of persisting drug use on long-term progression to AIDS has to be investigated further.

New evidence to reconcile in vitro and epidemiologic data on the possible role of heroin on CD4+ decline among HIV-infected injecting drug users

Long-term effects of drug type and other drug use related risk factors on CD4+ cell decline were assessed in 224 HIV-infected injecting drug users (IDUs) from Baltimore (ALIVE), USA, and 63 IDUs from Amsterdam, The Netherlands. Higher frequencies of borrowing used injection equipment since 1980 resulted in a higher CD4+ count already present before seroconversion (P = 0.049). Use of mainly heroin in the seroconversion interval resulted in a sharper CD4+ decline until the first 6 months after seroconversion (P = 0.004), but CD4+ values converged later on. This finding might reconcile earlier discordant epidemiological and laboratory study results regarding the possible effects of heroin.

Direct comparison of time to AIDS and infectious disease death between HIV seroconverter injection drug users in Italy and the United States: results from the ALIVE and ISS studies. AIDS Link to Intravenous Experiences. Italian Seroconversion Study

OBJECTIVE

To compare the rate of HIV disease progression in a sample of polydrug injectors (AIDS Link to Intravenous Experiences [ALIVE] study) with that in a sample of predominantly opiate injectors (Italian Seroconversion Study [ISS]).

DESIGN

Prospective cohort studies of HIV-positive individuals whose date of seroconversion (SC) is known with a good degree of precision. The ALIVE study involves a community-based cohort of injection drug users (IDU) in the United States and the ISS reports on a clinic-based cohort of seroconverters in Italy with different exposure modalities to HIV.

METHODS

Data from the two cohorts were combined. The date of SC was estimated as the midpoint in time between the last negative and the first positive HIV test. Time-to-event (i.e., AIDS or death from an infectious disease) statistical methods were used. Relative hazards (RH) of progression to event were adjusted by age at SC, gender, and year of SC.

RESULTS

Of the 1003 IDUs (251 from ALIVE and 752 from ISS), 226 progressed to AIDS, and 146 died after AIDS or from an infectious disease; of these, 10 were without an AIDS diagnosis. The two groups of IDUs differed in terms of age at SC (median, 35 years for ALIVE and 25 years for ISS), proportion of women (24% versus 31%), race (7.6% versus 100% white), and year of seroconversion (i.e., ISS participants seroconverted, on average, earlier than ALIVE participants). Although the univariate analysis suggested possible differences for progression to AIDS, or to death from infectious disease between cohorts, multivariate analyses that adjusted for age showed no significant differences by cohort, gender, race, or time of seroconversion. The median time to AIDS for 25-year-old persons was 12.3 years for ALIVE and 11.8 years for ISS; for 35-year-old persons, it was 8.5 and 8.2 years, respectively. These estimates were similar to those for non-IDUs observed in the ISS and to those from large cohort of homosexual men.

CONCLUSION

Our results confirm the importance of accounting for age when considering the incubation period for HIV infection. Despite differences in drug use characteristics, the similar median times to AIDS, for each age, between the two cohorts of IDUs and between the IDUs and the non-IDUs suggest a negligible effect of injection drug use on HIV progression.

Cell-associated infectious HIV-1 viral load as a predictor of clinical progression and survival among HIV-1 infected injection drug users and homosexual men

Cell-associated infectious HIV-1 viral load was measured using semi-quantitative microculture techniques to determine its predictive capability for progression to AIDS or survival among HIV-1 infected injecting drug users (IDU) and homosexual men (HM). The authors followed 296 IDU and 240 HM from February 1992 through September 1995 for: (i) death, (ii) AIDS, and (iii) AIDS or bacterial infection. At baseline, viral load was quantified using microculture techniques to determine infectious units per million peripheral blood mononuclear cells (IUPM). Data were analyzed using standard statistical methods for survival analysis. Of the 536 total participants, 106 died (20%), and 98 of the 481 AIDS-free participants developed AIDS (20%). The relative hazard of AIDS for a viral load of > or = 100 IUPM, relative to a negative culture (0 IUPM), was 6.73 (95% CI: 2.23-20.3) after adjusting for risk group, initial CD4+ count, and other covariates. The adjusted relative hazard of death for a viral load of > or = 100 IUPM vs. 0 IUPM was 2.57 (95% CI: 0.97 6.80). Viral load predicted time to death within the < 200 cells/ul CD4+ stratum. The predictive value of viral load on HIV-1 progression did not vary by risk group. These data show that cell associated infectious HIV-1 viral load was significantly predictive of progression across risk groups for AIDS and death among those severely immune compromised.

The differential infectivity and staged progression models for the transmission of HIV

Recent studies of HIV RNA in infected individuals show that viral levels vary widely between individuals and within the same individual over time. Individuals with higher viral loads during the chronic phase tend to develop AIDS more rapidly. If RNA levels are correlated with infectiousness, these variations explain puzzling results from HIV transmission studies and suggest that a small subset of infected people may be responsible for a disproportionate number of infections. We use two simple models to study the impact of variations in infectiousness. In the first model, we account for different levels of virus between individuals during the chronic phase of infection, and the increase in the average time from infection to AIDS that goes along with a decreased viral load. The second model follows the more standard hypothesis that infected individuals progress through a series of infection stages, with the infectiousness of a person depending upon his current disease stage. We derive and compare threshold conditions for the two models and find explicit formulas of their endemic equilibria. We show that formulas for both models can be put into a standard form, which allows for a clear interpretation. We define the relative impact of each group as the fraction of infections being caused by that group. We use these formulas and numerical simulations to examine the relative importance of different stages of infection and different chronic levels of virus to the spreading of the disease. The acute stage and the most infectious group both appear to have a disproportionate effect, especially on the early epidemic. Contact tracing to identify super-spreaders and alertness to the symptoms of acute HIV infection may both be needed to contain this epidemic.

Comparison of two measures of human immunodeficiency virus (HIV) type 1 load in HIV risk groups

Levels of viral burden were compared across risk group and gender populations among 485 human immunodeficiency virus type 1 (HIV-1)-infected participants consisting of 190 male injection drug users (IDUs), 92 female IDUs, and 203 homosexual men. Viral burden was quantified by a microculture technique to determine cell-associated infectious units per 10(6) peripheral blood mononuclear cells (IUPM) and by reverse transcriptase PCR (Amplicor) to determine plasma HIV RNA levels. Adjusting for CD4(+) cell count, females had a lower infectious HIV load than all males combined (0. 33 log10 lower; P = 0.004), and homosexual men had a 0.29 log10 higher infectious viral load than all IDUs combined (P = 0.001). For HIV RNA levels, females had lower levels than males (0.19 log10 lower; P = 0.04), but no differences were observed by risk group. After controlling for percent CD4(+) cells, no differences were found by risk group for either assay, but females still had a 0.25 log10 lower infectious viral load than males (P = 0.04) and a viral RNA load similar to that of males (P = 0.25). The correlation between infectious viral load and HIV RNA load was 0.58 overall, which did not differ by gender or risk group. Our data suggest that differences in viral load may exist by gender and that any differences observed by risk group are driven predominantly by gender or percent CD4(+) cell differences. These data also confirm a moderate correlation between cell-associated infectious viral load and plasma HIV RNA load, which appears to be similar by gender and across risk groups.

Sex differences in HIV-1 viral load and progression to AIDS

BACKGROUND

Plasma HIV-1 RNA measurements are used for initiation of antiretroviral treatments. Whether the viral-load association with prognosis is similar in women and men is unknown.

METHODS

We studied 812 specimens from 650 injection-drug users (IDUs) participating in a continuous observational study of patients based in a community clinic. HIV-1 load was measured by branched-chain DNA on samples from 527 IDUs from the baseline visit, and by reverse-transcriptase PCR and quantitative microculture on samples from 285 IDUs at a follow-up visit 3 years later. FNDINGS: Women had lower median viral-load measurements than men by branched-chain DNA (3365 vs 8907 copies/mL; p=0.001), reverse-transcriptase PCR (45416 vs 93130 copies/mL; p=0.02), and quantitative microculture (5 vs 8 infectious units per million peripheral blood mononuclear cells; p=0.015). This association remained even after adjustment for CD4 cell count, race, and drug use within the previous 6 months. Time to AIDS was statistically similar for men and women in a univariate proportional-hazards model and in a model adjusting for CD4 cell count. Proportional-hazards models showed that women with the same viral load as men had a 1.6-fold higher risk of AIDS (95% CI 1.10-2.32); or, equivalently, that women with half the viral load of men had a similar time to AIDS as men.

INTERPRETATION

Although a biological mechanism remains unclear, these data suggest that current recommendations for HIV-1 viral-load thresholds to initiate antiretroviral therapy should be revised downwards for women.

Methods for estimating HIV prevalence: A comparison of extrapolation from surveys on infection rate and risk behaviour with back-calculation for the Netherlands

OBJECTIVES

To compare HIV prevalence estimates (total number infected) by using extrapolation from surveys on infection rate and risk behaviour (EIR) in specific segments of the population and back-calculation (BC) on reported AIDS cases. To discuss potential sources of bias and error, and to identify areas for improvement of the methodology.

DESIGN

Systematic comparison and epidemiological assessment of data input, underlying assumptions, and output.

METHODS

Low, possibly unbiased and high estimates of HIV prevalence as of January 1996 for homo/bisexual men, injecting drug users. heterosexual men and women with multiple partners, and blood transfusion recipients and haemophiliacs were derived from surveys and continuous data collections on HIV infection rate and risk behaviour in the Netherlands between 1992 and 1996. These were compared with estimates (point and 95 % CI) by empirical Bayesian BC on AIDS cases 1982-1995.

RESULTS AND CONCLUSIONS

The estimate of HIV prevalence by EIR was 13,806 with low and high estimates of 9619 and 17,700, respectively. The HIV prevalence estimate by BC was 8812 (95% CI: 7759-9867). The available data from EIR are too limited for accurate estimates of HIV prevalence. EIR estimates could be improved considerably with more precise data on prevalence of risk behaviours and HIV prevalence rate for homosexual men. More confidence can be put in the BC estimates, but these could be underestimates because of the age effect on incubation time, pre-AIDS treatment and relapse of risk behaviour. BC estimates could be improved by a better representation of the incubation time distribution (including the effect of age there-upon), better data on the effectiveness and uptake of pre-AIDS antiretroviral treatment and prophylaxis of opportunistic infections, and on the level of underreporting.

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

Our objectives are to describe the progression of HIV disease and to assess the influence of hemophilia-related variables, age at infection, and antibodies to cytomegalovirus infection (anti-CMV) in a Greek cohort of 158 HIV-1-positive hemophilic men, who received prospective follow-up for up to 16 years after infection. A total of 79 patients had died, representing a cumulative progression rate of 72.4% (95% confidence interval [CI], 56.6-83.3). A significant proportion of the mortality (30%) resulted from conditions not formally related to AIDS, with liver failure and cerebral hemorrhage predominant. At 16 years after seroconversion, 66 patients had developed clinical AIDS, a cumulative progression rate of 58.2% (95% CI, 47.1%-86.3%) whereas 15 years after infection 81.5% (95% CI, 74.2%-87.9%) of the patients had AIDS or a CD4 cell count <200 cells/mm3. Hemophilia-related variables or presence of anti-CMV were not significantly associated with disease progression. Age at infection was a strong prognostic factor for all three endpoints. Appropriate modeling showed a nonlinear age effect, with a steeper increase of relative hazard for patients >40 years of age at seroconversion. The age effect remained significant even after controlling for current CD4 cell count. Further investigation is required to elucidate the mechanisms of the age effect and the contribution of HCV coinfection on the disease progression.

Association of syncytium-inducing phenotype of HIV-1 with CD4 cell count, viral load and sociodemographic characteristics

OBJECTIVES

To study whether syncytium-inducing (SI)/non-SI (NSI) phenotype of HIV-1 is associated with CD4+ lymphocyte count, plasma HIV RNA level, clinical stage and sociodemographic characteristics in antiretroviral-naive HIV-1-infected patients.

DESIGN

Cross-sectional analysis of single centre cohort study data.

METHODS

SI/NSI phenotype was determined using a cocultivation assay using patients' peripheral blood mononuclear cells and MT2 cells. Standard procedures were used for CD4+ cell counts and viral load measurements in plasma. Univariate and multivariate analyses of association of CD4+ cell counts, viral load, clinical stage, age, sex and mode of HIV transmission were performed.

RESULTS

In univariate analysis, SI phenotype was significantly associated with lower CD4+ cell counts, higher HIV RNA plasma levels, symptomatic HIV disease, male sex and age 32-36 years (middle tercile). In multivariate analysis, only lower CD4+ cell counts were associated with SI phenotype (odds ratio per increase of 100 x 10(6)/l, 0.54; 95% confidence interval, 0.38-0.78).

CONCLUSIONS

HIV-1 SI phenotype was associated with lower CD4+ cell counts but not with higher plasma viral load, clinical stage or sociodemographic variables.

Disease progression and survival in HIV-1-infected Africans in London

OBJECTIVE

To examine differences in progression to AIDS and death between HIV-1-positive Africans (most infected in sub-Saharan Africa and therefore with non-B subtypes) and HIV-1-positive non-Africans in London.

DESIGN

Retrospective cohort study of 2048 HIV-1-positive individuals.

SETTING

HIV-1-infected individuals attending 11 of the largest HIV/AIDS units in London.

PATIENTS

Subjects were 1056 Africans and 992 non-Africans seen between 1982-1995.

RESULTS

There were no differences in crude survival from presentation to death between Africans and non-Africans (median 82 and 78 months, respectively; P = 0.22). Africans progressed more rapidly to AIDS [hazard ratio (HR), 1.21; 95% confidence interval (CI), 1.02-1.45] but after adjustment for age, sex, Centers for Disease Control and Prevention category B symptoms and CD4+ lymphocyte count at presentation, year of HIV diagnosis and hospital attended, this difference was no longer significant (adjusted HR, 1.15; 95% CI, 0.93-1.43). Africans with AIDS had a reduced risk of death compared with non-Africans (HR, 0.78; 95% CI, 0.63-0.96) but not after adjustment for age, CD4+ lymphocyte count at AIDS, initial AIDS-defining conditions (ADC) and hospital attended (HR, 0.98; 95% CI, 0.76-1.27). Tuberculosis as the first ADC was associated with a 64% reduction in the risk of death. CD4+ lymphocyte decline was not significantly different between Africans and non-Africans (P = 0.18).

CONCLUSIONS

Differences in progression to AIDS and death and CD4+ lymphocyte decline between HIV-1-infected Africans and non-Africans in London could not be attributed to ethnicity or different viral subtypes. Age and the clinical and immunological stage at presentation, or AIDS, were the major determinants of outcome. Compared with other diagnoses, tuberculosis as the initial ADC was associated with increased survival. Lack of access to health care and exposure to environmental pathogens are the most likely causes of reduced survival with AIDS in Africa, rather than inherently different rates of progression of immune deficiency due to racial differences or viral subtypes.

Hepatitis C virus and HIV coinfection

The world-wide prevalence of hepatitis C virus (HCV) is approximately 1%. Being primarily a blood-borne virus, the major risk factors for HCV include the receipt of blood and blood products, as well as intravenous drug use. As a result, many individuals infected with HIV are also infected with HCV. Any effect of coinfection on progression of either HIV or HCV is likely to have a tremendous impact on the mortality and morbidity of these individuals and should be considered when managing coinfected individuals. This review will describe the epidemiology and clinical manifestations of HCV and will consider the evidence for an impact of coinfection on the progression of both viruses.

Increased losses of CD4+CD45RA+ cells in late stages of HIV infection is related to increased risk of death: evidence from a cohort of 347 HIV-infected individuals

OBJECTIVE

To examine changes in the distribution of CD4+CD45RA+ (naive) and CD4+CD45RO+ (memory) lymphocytes in various stages of HIV infection and the effect of these changes on disease progression.

DESIGN AND METHODS

Expression of CD45RA+ and CD45RO+ on CD4+ lymphocytes was analysed by flow cytometry in a prospectively followed cohort of 300 HIV-infected individuals (median follow-up time, 2.90 years; range, 0.02-4.54 years) and in a group of 102 age- and sex-matched uninfected controls. Survival analysis was performed considering AIDS development and death as endpoints.

RESULTS

The median CD4+CD45RA+/CD45RO+ ratio was 1.3 (25-75% quartiles, 0.9-2.4) in controls; it was increased to 1.8 (1.1-2.5) in 40 HIV-infected individuals with CD4+ cell counts > 500 x 10(6)/l (P < 0.05); it was similar at 1.4 (0.8-2.0) in 106 HIV-infected individuals with CD4+ cell counts of 200-500 x 10(6)/l; and it was decreased to 0.9 (0.5-1.4) in 154 HIV-infected individuals with CD4+ cell counts < 200 x 10(6)/l (P < 10[-6]). When fitted in a Cox model adjusting for the total number of CD4+ cells and age a lower concentration of CD4+CD45RA+ cells was associated with an increased risk of dying. The concentration of CD4+CD45RO+ cells was not significantly associated with AIDS or death in age- and CD4+ cell count-adjusted Cox models.

CONCLUSIONS

This study confirms a selective loss of memory CD4+ cells early in HIV infection followed by increased loss of naive CD4+ cells in later stages of the infection. The loss of naive CD4+ cells seems to be important in the pathogenesis of terminal HIV infection.

The influence of drug use patterns on the rate of CD4+ lymphocyte decline among HIV-1-infected injecting drug users

OBJECTIVES

To assess the relationship between various injecting drug use patterns and the rate of CD4+ lymphocyte decline in HIV-1-infected injecting drug users in Baltimore, Maryland, USA.

METHODS

A cohort of 605 HIV-1-infected injecting drug users was recruited between 1988 and early 1989 in East Baltimore using extensive community outreach techniques. The participants were interviewed semi-annually to collect information on drug use practices. The outcome measure of interest was the rate of CD4+ lymphocyte decline between pairs of CD4+ lymphocyte counts. A mixed model was used to evaluate the relationship between the change in CD4+ lymphocyte count per month and previous CD4+ lymphocyte count and various drug use variables.

RESULTS

The 605 HIV-infected injecting drug users had a median initial CD4+ lymphocyte count of 513 cells x 10(6)/l. Using 3209 paired observations, the mean change in CD4+ lymphocyte count was -3.2 cells x 10(6)/l per month. The rate of decline was higher in those with a higher level of CD4+ lymphocytes (P < 0.01) and length of drug use (P < 0.01), but did not vary by injection frequency or injection intensity of specific drug types. Although animal studies have suggested that the pattern of drug administration (continuous versus intermittent) and episodes of withdrawal or overdose might impact the rate of CD4+ lymphocyte decline, this was not observed in the present study.

CONCLUSION

Patterns of injecting drug use, based on self-report, were not associated with the rate of decline in CD4+ lymphocytes.

How many HIV-infected individuals may be defined as long-term nonprogressors? A report from the Italian Seroconversion Study. Italian Seroconversion Study Group (ISS)

We prospectively examined a cohort of HIV-positive persons with an accurately estimated date of HIV seroconversion who were infected through injecting drug use or sexual contact to estimate the proportion of long-term nonprogressors (LTNP), considering four definitions of LTNPs. We also evaluated whether factors such as gender, age, and HIV-exposure category were associated with being LTNP; we determined the overlap among the definitions and compared the CD4 and CD8 counts and the CD4/CD8 decline among LTNPs and "moderate" and "fast" progressors. Of the 528 persons selected for analysis, 2 to 4% were considered LTNPs, depending on the definition. The proportion of LTNPs varied by definition, and there was little overlap among definitions. The LTNPs did not appear to differ from "moderate" and "fast" progressors with regard to main demographic characteristics, and they showed a better trend of immunological parameters, appearing to have a slower progression rather than a permanently arrested infection.