Off the Wires
Off the Wires
The major effect of the progressive immune suppression caused by HIV-1 is an increased risk of a number of opportunistic infections and rare tumor types that define the clinical spectrum of AIDS. It has been reported that time from infection (seroconversion) is a strong prognostic marker for the onset of AIDS. Other reports have suggested that individuals with similar CD4 cell counts have similar rates of progression independent of time from seroconversion. The objective of the CASCADE study (J Acquir Immune Defic Syndr. 2001;28:158-165) was to investigate, using a very large set of pooled cohorts, whether there is a residual effect of time from infection on the risk of AIDS and to quantify this effect in terms of an increase in risk. The study also investigated this objective for each specific AIDS-defining illness.
Concerted Action on SeroConversion to AIDS and Death in Europe (CASCADE) is a collaboration of investigators involved with 19 cohorts in Europe and Australia that began in 1997. All cohorts include persons for whom it was possible to estimate the time of HIV seroconversion. All analyses ended with data on December 31, 1995, in order to avoid confounding the findings with HAART, which became widely prescribed after that date. Using pooled data from the 19 seroconverter cohorts, the authors considered time to the first AIDS-defining event following a CD4 cell count below 500/mL, 350/mL, and 200/mL. All data were adjusted for age, gender, exposure category, and HIV test interval in Cox models stratified by cohorts. Of 3825, 3006, and 1804 persons reaching CD4 cell thresholds of 500/mL, 350/mL, and 200/mL, respectively, AIDS developed in 1274, 1192, and 985, respectively. The authors found a significant effect of time from seroconversion on the risk of AIDS, even after adjusting for updated CD4 cell counts. In the 3 cohort groups, the risks after 1 year were 7%, 6%, and 4%, respectively. The effect of time appeared to be nonlinear, with no increase in the risk of AIDS after 4 years from seroconversion. The residual effect of time differed significantly according to type of AIDS-defining event initially diagnosed. Time from seroconversion to CD4 cell threshold was not associated with progression to Pneumocystis carinii pneumonia (PCP), herpes simplex virus (HSV) infection, and deaths in persons without AIDS. Conversely, time from seroconversion was found to have an association with progression to Kaposi sarcoma (KS) and mycobacterial disease not including tuberculosis.
Given the results of the study, the authors advised against the use of time in assessing an infected person's risk of AIDS over and above a given CD4 cell count. "Such knowledge, however, is of more benefit when assessing a patient's risk of KS or mycobacterial disease, other than tuberculosis, rather than PCP or HSV infection," they said. [CDC HIV/STD/TB Prevention News Update, Thursday, November 8, 2001]
The major effect of the progressive immune suppression caused by HIV-1 is an increased risk of a number of opportunistic infections and rare tumor types that define the clinical spectrum of AIDS. It has been reported that time from infection (seroconversion) is a strong prognostic marker for the onset of AIDS. Other reports have suggested that individuals with similar CD4 cell counts have similar rates of progression independent of time from seroconversion. The objective of the CASCADE study (J Acquir Immune Defic Syndr. 2001;28:158-165) was to investigate, using a very large set of pooled cohorts, whether there is a residual effect of time from infection on the risk of AIDS and to quantify this effect in terms of an increase in risk. The study also investigated this objective for each specific AIDS-defining illness.
Concerted Action on SeroConversion to AIDS and Death in Europe (CASCADE) is a collaboration of investigators involved with 19 cohorts in Europe and Australia that began in 1997. All cohorts include persons for whom it was possible to estimate the time of HIV seroconversion. All analyses ended with data on December 31, 1995, in order to avoid confounding the findings with HAART, which became widely prescribed after that date. Using pooled data from the 19 seroconverter cohorts, the authors considered time to the first AIDS-defining event following a CD4 cell count below 500/mL, 350/mL, and 200/mL. All data were adjusted for age, gender, exposure category, and HIV test interval in Cox models stratified by cohorts. Of 3825, 3006, and 1804 persons reaching CD4 cell thresholds of 500/mL, 350/mL, and 200/mL, respectively, AIDS developed in 1274, 1192, and 985, respectively. The authors found a significant effect of time from seroconversion on the risk of AIDS, even after adjusting for updated CD4 cell counts. In the 3 cohort groups, the risks after 1 year were 7%, 6%, and 4%, respectively. The effect of time appeared to be nonlinear, with no increase in the risk of AIDS after 4 years from seroconversion. The residual effect of time differed significantly according to type of AIDS-defining event initially diagnosed. Time from seroconversion to CD4 cell threshold was not associated with progression to Pneumocystis carinii pneumonia (PCP), herpes simplex virus (HSV) infection, and deaths in persons without AIDS. Conversely, time from seroconversion was found to have an association with progression to Kaposi sarcoma (KS) and mycobacterial disease not including tuberculosis.
Given the results of the study, the authors advised against the use of time in assessing an infected person's risk of AIDS over and above a given CD4 cell count. "Such knowledge, however, is of more benefit when assessing a patient's risk of KS or mycobacterial disease, other than tuberculosis, rather than PCP or HSV infection," they said. [CDC HIV/STD/TB Prevention News Update, Thursday, November 8, 2001]
Source...