Progression to AIDS among Italian HIV-seropositive haemophiliacs. Italian Group

HLA and in vitro susceptibility to HIV infection

Since the beginning of the epidemic of acquired immunodeficiency syndrome (AIDS), evidence has accumulated that genetic factors are involved in the pathogenesis of the disease. Among the candidate molecules suspected to control susceptibility to human immunodeficiency virus (HIV) infection and fast or slow progression of AIDS are the human leukocyte antigens (HLA). Investigating HLA-HIV correlation was mainly performed by investigating cohorts of patients with HIV/AIDS for a period of time and then statistically correlating certain features of AIDS with particular HLA alleles. This type of in vivo investigations resulted in the generation of an immense literature on the subject with so many HLA alleles being found to correlate with certain features of AIDS. Because of the complexity of AIDS pathogenesis and the involvement of many factors in the disease process, the different investigators failed to agree on the involvement of certain HLA molecules in AIDS pathogenesis. Some reports deny, or fail to confirm the existence of association between HLA and HIV progression to AIDS. This is probably due to the different ethnic backgrounds of the populations studied, the complexity of the HLA system, and to the ways these studies were conducted. This article briefly addresses our current knowledge on the HLA-HIV correlation in vivo and discusses alternative in vitro studies.

The practical significance of potential biases in estimates of the AIDS incubation period distribution in the UK register of HIV seroconverters

OBJECTIVES

To assess the practical significance of the following sources of bias for estimates of the AIDS incubation period in a large seroconverter cohort: estimation of the time of seroconversion; presentation with an HIV-related illness; preferential inclusion of survivors; loss to follow-up and analysis cut-off date; the inclusion of Kaposi's sarcoma as an AIDS event; death without an AIDS diagnosis; and representativeness of the HIV population.

METHODS

Standard non-parametric survival methods were used to estimate the AIDS incubation period distribution. The practical importance of each type of bias was assessed using various sensitivity analyses.

RESULTS

The potential sources of bias of most practical importance in this study were the right-censoring strategy and that due to lack of documentation of a negative HIV antibody test. Five different right-censoring strategies gave estimates of the median time to AIDS ranging from 8.1 to 10.8 years for the 1202 individuals enrolled in the UK Register of HIV Seroconverters. HIV-infected persons with a history of a previous antibody negative test which could not be verified appeared to progress to AIDS more rapidly than persons with such verification (Relative risk = 1.8, 95% confidence intervals = 1.3-2.3).

CONCLUSIONS

As a number of possible causes of bias can impact on results, care must be taken to document them and control for them wherever possible. In our study, this was particularly relevant in relation to the documentation of a previous HIV antibody negative test and the choice of analysis cut-off dates. As methods may differ between cohorts, comparison of the published results from one cohort with those of another may be misleading.

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.

Five myths about AIDS that have misdirected research and treatment

A number of widely repeated and factually incorrect myths have pervaded the AIDS research literature, misdirecting research and treatment. Five of the most outstanding are: 1) that all risk groups develop AIDS at the same rate following HIV infection; 2) that there are no true seroreversions following HIV infection; 3) that antibody is protective against HIV infection; 4) that the only way to treat AIDS effectively is through retroviral therapies; and 5) that since HIV is so highly correlated with AIDS incidence, it must be the sole necessary and sufficient cause of AIDS. A huge body of research, reviewed in this paper, demonstrates the falsity of these myths. 1) The average number of years between HIV infection and AIDS is greater than 20 years for mild hemophiliacs, 14 years for young severe hemophiliacs, 10 years for old severe hemophiliacs, 10 years for homosexual men, 6 years for transfusion patients of all ages, 2 years for transplant patients, and 6 months for perinatally infected infants. These differences can only be explained in terms of risk-group associated cofactors. 2) Seroreversions are common. Between 10 and 20 percent of HIV-seronegative people in high risk groups have T-cell immunity to HIV, and may have had one or more verified positive HIV antibody tests in the past. 3) Antibody, far from being protective against HIV, appears to be highly diagnostic of loss of immune regulation of HIV, and some evidence of antibody-enhancement of infection exists. 4) Non-retroviral treatments of HIV infection, including safer sex practices, elimination of drug use, high nutrient diets, and limited reexposure to HIV and its cofactors have proven to be effective means of preventing or delaying onset of AIDS. 5) Many immunosuppressive factors, including drug use, multiple concurrent infections, and exposure to alloantigens, are as highly correlated with AIDS risk groups as HIV. These data are more consistent with AIDS being a multifactorial or synergistic disease than a monofactorial one.

Epidemiology of hemophilia and of HIV infection in Italy. GICC. Gruppo Italiano Coagulopatie Congenite

To evaluate the incidence and prevalence of hemophilia in Italy and the impact of HIV infection on the Italian hemophiliac population, data from a computerized national registry of patients from 95% of the hemophilia care centers in Italy were analyzed. A total of 4643 patients were included in the registry. The prevalence of hemophilia A was 8.2 per 100,000 males, with no significant regional differences; for hemophilia B the corresponding figure was 1.5 per 100,000. Temporal trends in hemophilia incidence suggest that the diagnosis of mild and moderate hemophilia has improved. The overall HIV prevalence was 26% and was significantly (p < 0.001) higher in patients with hemophilia B (47.1%) compared to those with hemophilia A (26.8%) or other diseases (16.5%). The highest rate of HIV seropositivity was among patients 20-29 years of age. The annual amount of clotting factor concentrates received was significantly (p < 0.001) higher in HIV seropositive patients than in those who were seronegative. Antibody testing was never performed on 10.1% of severely affected patients. The number of patients in the Italian registry was similar to the number that would have been expected based on prevalence estimates from other countries. In comparison with other countries, the prevalence of HIV infection recorded in Italy was lower in persons with hemophilia A, but higher in those with hemophilia B. Our study demonstrates the usefulness of a registry in delineating the epidemiology of hemophilia and in studying risk factors for HIV infection. It also underlines the need for continuing surveillance of this population.

Median time from seroconversion to AIDS in Italian HIV-positive haemophiliacs: different parametric estimates

The purpose of this study was to estimate the median incubation time between human immunodeficiency virus (HIV) infection and onset of acquired immunodeficiency syndrome (AIDS), using three parametric models and six estimates of seroconversion time. Study subjects were 732 HIV-positive haemophiliacs enrolled in the Italian Registry of patients with congenital coagulation disorders. Seroconversion time was estimated for each subject according to six different criteria, based on three distributions of seroconversion (uniform, uniform on three sub-intervals and truncated Weibull) and two indices synthesizing each distribution (median and median of three random values). The estimated seroconversion times were subsequently used as starting points in the analysis of incubation. This was performed applying Kaplan-Meier non-parametric survival analysis, and fitting to incubation data three probability density functions, representing three different situations with respect to the hazard of developing AIDS following seroconversion (namely Weibull (WE), generalized exponential (GE) and log-logistic (LL)). The cumulative incidence over an 8-year period ranged from 14.9 to 17.8 per cent when applying the Kaplan-Meier method, from 14.1 to 17.2 per cent when using the WE function, from 14.5 to 17.3 per cent when using the GE function and from 14.4 to 17.3 per cent when using the LL function, depending on the estimate of seroconversion time used. Similarly, the median incubation times ranged from 12.6 to 15.0 years with the WE function, from 14.0 to 16.5 years with the GE function, and from 13.4 to 16.1 years with the LL function. The presence of a bound on the increase of the hazard function seems to affect the incubation more strongly than the eventual decrease following the attainment of the maximum risk. This may be due to the decrease in the hazard beginning when most of the seropositive subjects have already developed AIDS.

Incidence of AIDS in HIV-1 infected thalassaemia patients. European and Mediterranean W.H.O. Working Group on Haemoglobinopathies and Cooleycare

To estimate the cumulative incidence of acquired immunodeficiency syndrome (AIDS) in thalassaemia major patients (TMP) human immunodeficiency virus (HIV-1) infected through transfusion, 79 seropositive TMP were studied. At inclusion, mean age was 12.4 +/- 6.6 years; 40 were men; 21 were splenectomized. Centers for Disease Control, 1986 (CDC) stages and prescription of zidovudine were noted at least once a year. Cumulative incidence of AIDS and standard error were calculated using non parametric life table method. Age, sex, acute infection and splenectomy associations with progression to AIDS were tested using Breslow statistic. The median follow-up period was 4 years 11 months. At the end of the study period, 43 TMP were in CDC stage II, 23 in CDC stage III and 13 in CDC stage IV, including seven AIDS cases, of whom three had died. Four subjects died of other causes. Only two patients were treated with AZT prior to the occurrence of AIDS. Rate of progression to AIDS was not associated with acute infection, splenectomy, age, or sex. A cumulative AIDS incidence rate of 1.4% (SE 1.3%) was observed at 3 years and of 9% (SE 4%) at 5 years.

Effects of different parametric estimates of seroconversion time on analysis of progression to AIDS among Italian HIV-positive haemophiliacs

The purpose of this study was to estimate seroconversion time using different parametric methods and to assess their influence on the estimation of the incubation time between HIV infection and onset of AIDS. Study subjects were 712 HIV-positive haemophiliacs enrolled in the Italian National Registry of patients with congenital coagulation disorders. Seroconversion time was estimated using the mid-point of each seroconversion interval (MID), the median of each interval under an estimated uniform distribution with cutpoints at December 1981 and December 1985 (MUU), the median of each interval under an estimated Weibull distribution (MUW), and the median of three random values drawn from each interval under the Weibull distribution (RUW). Kaplan-Meier survival analysis showed that the cumulative incidence of AIDS over a 7-year period was 11.6 per cent (SE 1.3 per cent) when using the MID estimate of seroconversion time, 10.8 per cent (1.2 per cent) with the MUU estimate, and 13.4 per cent (1.3 per cent) and 12.3 per cent (1.3 per cent) when using MUW and RUW estimates, respectively. This study demonstrates that the estimate of seroconversion time does not seem to be a major factor affecting estimates of AIDS incidence since the different techniques for estimating HIV seroconversion time yielded very similar results.