A population-based comparison of the clinical course of children and adults with AIDS

Health and federal budgetary effects of increasing access to antiretroviral medications for HIV by expanding Medicaid

OBJECTIVES. This study modeled the health and federal fiscal effects of expanding Medicaid for HIV-infected people to improve access to highly active antiretroviral therapy.

METHODS

A disease state model of the US HIV epidemic, with and without Medicaid expansion, was used. Eligibility required a CD4 cell count less than 500/mm3 or viral load greater than 10,000, absent or inadequate medication insurance, and annual income less than $10,000. Two benefits were modeled, "full" and "limited" (medications, outpatient care). Federal spending for Medicaid, Medicare, AIDS Drug Assistance Program, Supplemental Security Income, and Social Security Disability Insurance were assessed.

RESULTS

An estimated 38,000 individuals would enroll in a Medicaid HIV expansion. Over 5 years, expansion would prevent an estimated 13,000 AIDS diagnoses and 2600 deaths and add 5,816 years of life. Net federal costs for all programs are $739 million (full benefits) and $480 million (limited benefits); for Medicaid alone, the costs are $1.43 and $1.17 billion, respectively. Results were sensitive to awareness of serostatus, highly active antiretroviral therapy cost, and participation rate. Strategies for federal cost neutrality include Medicaid HIV drug price reductions as low as 9% and private insurance buy-ins.

CONCLUSIONS

Expansion of the Medicaid eligibility to increase access to antiretroviral therapy would have substantial health benefits at affordable costs.

Survival by AIDS defining condition in rural Uganda

OBJECTIVES

To report the initial AIDS defining conditions, CD4 lymphocyte counts around the time of AIDS diagnosis, and survival by AIDS defining condition in a population based cohort in rural Uganda.

METHODS

Participants in an HIV natural history cohort in rural Uganda were reviewed every 3 months at routine visits and at other times when they were ill. The date and nature of the first AIDS defining condition in participants developing AIDS during follow up between the start of the cohort in 1990 and the end of 1998 were noted. The CD4 count at, or within, 3 months of this time was recorded for those participants who developed AIDS (WHO stage 4) after 1993.

RESULTS

The median survival from developing AIDS to death was 9.3 months and the median CD4 lymphocyte count around the time of developing AIDS was 150 cells x 10(6)/l. The most frequent AIDS defining conditions were wasting syndrome, oesophageal candidiasis, and mucocutaneous herpes simplex virus infection (HSV) for more than 1 month. The median survival with wasting syndrome, Kaposi's sarcoma, and oesophageal candidiasis was less than 3.5 months; however, survival with cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis was greater than 20 months. There was little relation between CD4 count around the time of development of the AIDS defining condition and the median survival with that condition.

CONCLUSIONS

The survival for most AIDS defining conditions was generally shorter and the median CD4 lymphocyte count higher than studies reported from developed countries. However, the conditions with the longest survival (cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis) had a similar survival to that in developed countries and these conditions have a high background level in this population.

Maternal and infant factors predicting disease progression in human immunodeficiency virus type 1-infected infants. Women and Infants Transmission Study Group

BACKGROUND

Infants with perinatally acquired human immunodeficiency virus type 1 (HIV-1) infection have widely variable courses. Previous studies showed that a number of maternal and infant factors, when analyzed separately, are associated with infant HIV-1 disease progression. In this study, clincal, virologic, and immunologic characteristics in the mothers and infants were examined together to determine the predictors of disease progression by 18 months of age and the associations with rapid progression during the first 6 months of life.

METHODS

One hundred twenty-two HIV-1-infected women whose infants were HIV-1 infected were identified from the Women and Infants Transmission Study (WITS) cohort. WITS is a longitudinal natural history study of perinatal HIV-1 infection carried out in 6 sites in the continental United States and in Puerto Rico. The women were enrolled during pregnancy and their infants were enrolled at the time of delivery and followed prospectively by a standardized protocol. Virologic and immunologic studies were performed in laboratories certified by National Institutes of Health-sponsored quality assurance programs. Maternal factors in pregnancy were used as potential predictors of infant disease progression (progression to Centers for Disease Control and Prevention [CDC] Clinical Class C disease or death by 18 months of age) or as correlates of progression at <6 months of age. Infant factors defined during the first 6 months of life were used as potential predictors of progression during 6 to 18 months of age and as correlates of progression at <6 months of age.

RESULTS

Progression by 18 months of age occurred in 32% of infants and by 6 months of age in 15%. Maternal characteristics that, by univariate analysis, were significant predictors of infant disease progression by 18 months of age were elevated viral load, depressed CD4(+)%, and depressed vitamin A. CD8(+)%, CD8(+) activation markers, zidovudine (ZDV) use, hard drug use, and gestational age at delivery were not. When examined in a combined multivariate analysis of maternal characteristics, only vitamin A concentration independently predicted infant progression. Infant characteristics during the first 6 months of life that, by univariate analysis, were associated with disease progression included elevated mean viral load at 1 to 6 months of age, depressed CD4(+)%, CDC Clinical Disease Category B, and growth delay. Early HIV-1 culture positivity (<48 hours), CD8(+)%, CD8(+) activation markers, and ZDV use during the first month of life did not predict progression. Multivariate analysis of infant characteristics showed that the only independent predictors were progression to CDC Category B by 6 months of age (odds ratio [OR], 5.80) and mean viral load from 1 to 6 months of age (OR, 1.99). The final combined maternal and infant analysis included the significant maternal and infant characteristics in a multivariate analysis. It showed that factors independently predicting infant progression by 18 months of age were progression to CDC Category B by 6 months of age (OR, 5.80) and elevated mean HIV-1 RNA copy number at 1 to 6 months of age (OR, 1.99). The characteristics associated with rapid progression to CDC Category C disease or death by 6 months of age were also examined. The only maternal characteristic associated with progression by 6 months in multivariate analysis was low maternal CD4(+)%. The infant characteristics associated with progression by 6 months of age in multivariate analysis were depressed mean CD4(+)% from birth through 2 months and the presence of lymphadenopathy, hepatomegaly, or splenomegaly by 3 months. Infant ZDV use was not assocciated with rapid progression.

CONCLUSION

The strongest predictors of progression by 18 months are the presence of moderate clinical symptoms and elevated RNA copy number in the infants in the first 6 months of life. In contrast, progression by 6 months is associated with maternal and infant immun

Country-specific estimates and models of HIV and AIDS: methods and limitations

OBJECTIVE

This paper presents the methods used to calculate the end of 1997 country-specific estimates of HIV and AIDS produced by the UNAIDS/WHO Working Group on Global HIV/AIDS and STD Surveillance. The objective of this exercise was to improve estimates on HIV/AIDS by using country-specific models of HIV/AIDS epidemics. The paper describes and discusses the processes and obstacles that were encountered in this multi-partner collaboration including national and international experts.

METHODS

The 1997 estimates required two basic steps. First, point prevalence estimates for 1994 and 1997 were carried out and the starting year of the epidemic was determined for each country. The procedures used to calculate the estimates of prevalence differed according to the assumed type of the epidemic and the available data. The second step involved using these estimates of prevalence over time and the starting date of the epidemic to determine the epidemic curve that best described the spread of HIV in each particular country. A simple epidemiological program (EPIMODEL) was used for the calculation of estimates on incidence and mortality from this epidemic curve.

RESULTS

Regional models that were used in previous estimation exercises were not able to capture the diversity of HIV epidemics between countries and regions. The result of this first country-specific estimation process yielded higher estimates of HIV infection than previously thought likely, with over 30 million people estimated to be living with HIV/AIDS. The application of survival times that are specific to countries and regions also resulted in higher estimates of mortality, which more accurately describe the impact of the epidemics. At the end of 1997, it was estimated that 11.7 million people worldwide had died as a result of HIV/AIDS since the beginning of the epidemic.

CONCLUSION

This exercise is an important step in improving understanding of the spread of HIV in different parts of the world. There are, however, shortcomings in the current systems of monitoring the epidemic. Improvements in HIV surveillance systems are needed in many parts of the world. In addition, further research is needed to understand fully the effects of the fertility reduction as a result of HIV, differing sex ratios in HIV infection and other factors influencing the course and measurement of the epidemic.

Epidemiology of pediatric AIDS in Puerto Rico: 1981-1998

The objective of this study was to describe the AIDS-defining conditions (ADC) and survival experience of pediatric AIDS cases (< 13 years age) reported in Puerto Rico. A descriptive analysis of the data gathered by the Puerto Rico AIDS Surveillance System was performed. Data for the 377 pediatric AIDS cases reported from January 1981 through June 1998 were reviewed. Survival curves following AIDS diagnosis were estimated using the Kaplan--Meier method and differences between curves were assessed by the Wilcoxon test. The majority (61%) of the cases were diagnosed before 2 years of age, and nearly 94% of them acquired the infection through perinatal transmission. The most common ADC were Pneumocystis carinii pneumonia (PCP) (23%), wasting syndrome (19.4%), and esophageal candidiasis (19.1%). The overall median survival time during the study period was 53.5 (95% CI: 38.0-106.2) months. Children < 1 year of age had a significantly shorter median survival time compared with older ages (p < 0.05). The survival experience in children diagnosed with PCP, pulmonary candidiasis, cytomegalovirus, and lymphocytic interstitial pneumonia (LIP) was significantly different (p < 0.05) to those children not diagnosed with these conditions. Although patients diagnosed after 1990 showed a median survival time longer than those diagnosed prior to 1990, the difference did not reach statistical significance (p > 0.05). The frequency of several ADC and median survival time of Puerto Rican children differed from those reported in the United States. This may reflect differences in diagnostic procedures or reporting practices.

Frequency and predictors of medically attended injuries in HIV-infected children

The extent to which medically attended injuries complicate the clinical course of HIV-infected (HIV+) children is unknown. In a cohort of HIV+ children delivered from 1985 to 1990 and aged less than 60 months, we determined medically attended injuries per 100 child-years, Injury Severity Scores (ISS), and predictors of medically attended injuries by using New York State Medicaid claims from 1986 to 1992 linked to birth certificates. Injury rates and ISS were compared to those of a population of black, inner city children aged less than 60 months from emergency room records. HIV+ children had slightly more injuries (19.3 vs. 16.8/100 child-years) but similar ISS (2.4 vs. 2.3). Predictors of injuries in HIV+ children included younger maternal age (24/100 child-years, p = 0.008) and delivery outside of New York City (29/100 child-years, p = 0.02). Illicit drug use and alcohol use were associated with greater ISS while cocaine use was associated with a higher rate of possibly intentional injuries. Medically attended injuries affected one in five HIV+ children in our cohort annually, slightly more than the comparison population. Specific maternal and birth characteristics such as substance abuse and younger age at delivery may help target at-risk children.

Predictors of survival in children with acquired immunodeficiency syndrome in Italy, 1983 to 1995

To evaluate length and predictors of survival among children with AIDS, 529 pediatric cases diagnosed in Italy from 1983 to August 1995 were reviewed. Data were analyzed using Kaplan-Meier curves and the Cox proportional hazards regression model. Various survival patterns were subsequently analyzed. All survival analyses were truncated on March 1, 1996. Cases were examined by gender, age at diagnosis, HIV transmission category, type and number of the first AIDS-defining diseases, level of immunosuppression at AIDS diagnosis, HIV transmission category of the mother, and period of diagnosis. The overall median survival time was approximately 24 months. There wer no significant differences in survival by gender, HIV transmission category, mother's risk factor, or period of diagnosis. The Kaplan-Meier analysis showed the greatest differences in survival time between children less than 6 months of age at diagnosis (median survival 6.4 months) and all others (median 28.7 months). Children with recurrent bacterial infections or lymphoid interstitial pneumonia (LIP) had a survival time at least four times longer than those with Pneumocystis carinii pneumonia (PCP), mycobacteriosis, cytomegalovirus, tumors, or progressive multifocal leukoencephalopathy. At the multivariate analysis, the risk of death was lower among children with LIP (Relative Hazard [RH] 0.72) compared with other opportunistic diseases, whereas age less than 6 months, diagnosis of PCP or of two or more diseases, and severe immunosuppression at diagnosis increased the risk of death. Both demographic factors (age) and clinical factors (type and number of initial diseases, level of immunosuppression) were found to be independent predictors of a poor prognosis in children with AIDS. This information may be of use in improving prognosis and planning healthcare and treatment.

Modelling the costs of paediatric HIV infection and AIDS: comparison of infected children born to screened and unscreened mothers

OBJECTIVE

To estimate the cost of managing children with HIV/AIDS in the UK from a health service perspective.

DESIGN AND METHODS

Epidemiological, resource use and unit cost data were combined within a decision analytic model. A Markov model was developed to predict the prognoses of HIV-infected children under different assumptions about natural history, treatment efficacy and the timing of antiretroviral therapy. Resource use estimates for various stages of HIV/AIDS were based on published data relating to the UK health service and clinical judgement; unit cost data were taken from a London centre.

RESULTS

The base-case results suggest that the cost of caring for an HIV-infected child is higher if the mother's infection was known about at or before the child's birth (antenatal screened cohort): lifetime costs ranged from 46 427 pound sterling to 119 502 pound sterling per child in the screened cohort and from 38 691 pound sterling to 86 014 pound sterling in the unscreened cohort. However, the screened cohort benefited from longer life expectancy (base-case, 11.66 versus 10.09 years) and AIDS-free life expectancy (base-case, 7.13 years versus 6.22 years). Results are sensitive to assumptions about natural history and treatment efficacy: for example, if antiretroviral therapy was initiated at birth, and assuming optimistic natural history parameters, discounted costs could increase to 215 077 pound sterling and the additional lifetime cost of a child born to a screened mother could be 72 491 pound sterling.

CONCLUSIONS

Results reflect the marked uncertainty regarding the cost of, and prognosis for, children with HIV/AIDS in the new era of more potent antiretroviral combination therapies. These results are part of an assessment of the relative cost-effectiveness of alternative antenatal HIV testing strategies.

Immunological and virological markers of disease progression in HIV-infected children

Polymerase chain reaction (PCR), virus culture and antigen detection assays are useful for early detection of vertically transmitted human immunodeficiency virus type 1 (HIV-1) infection in infants under 12 months of age. Sixty-four children born to HIV-1-seropositive mothers were evaluated. Thirteen children (20.3%) were repeatedly positive by PCR analysis. There was 100% concordance between the results obtained from PCR and culture assays. Measurement of p24 antigen in serum was, in contrast, a less sensitive marker of HIV infection: only 5/13 infants had positive p24 antigen results. We have investigated the relationship among the HIV-1 biological phenotype, replicative capacity of viral isolates, HIV RNA copy number in plasma, p24 antigenaemia, CD4 T lymphocyte counts and the clinical status in 13 HIV-infected infants. Six out of 13 HIV-1 isolates from these patients were classified as rapid/high and seven as slow/low. We have found a significantly positive correlation between the replication rate of HIV isolates and their capacity to induce syncytia in vitro. The HIV-1 isolates with rapid/high and syncytium-inducing phenotype, and isolates with slow/low and non-syncytium-inducing phenotype were obtained from infants who had HIV-1 RNA copy number ml(-1) plasma values of 27654-83520 and 1342-34321, respectively. Levels of HIV-1 RNA were measured in sequential plasma samples from three HIV-infected infants and their biological properties determined in vitro. Our findings indicate that infants who carried viruses with more cytophatic biological phenotype and who had higher viral RNA copy numbers in blood were more likely to have lower CD4+ T cell counts and more likely to develop full-blown AIDS.

Prenatal care and birth outcomes of a cohort of HIV-infected women

Adequate prenatal care has been linked to improved birth outcomes in general populations but has not been assessed in HIV-infected women. We examined longitudinal claims files and vital statistics records for women in the New York State Medicaid HIV/AIDS data base delivering a singleton from 1985 through 1990. Adequacy of the self-reported number of prenatal visits was assessed by the Kessner index. In logistics models, we estimated the association of prenatal care, illicit drug use, and other maternal characteristics with three outcomes; low birth weight, preterm birth, and small-for-gestational-age. Of 2,254 singletons delivered by this HIV-infected cohort, 28% were low birth weight, 23% were preterm birth, and 20% were small for gestational age. Two-thirds had inadequate prenatal care. Non-drug users had 57 and 26% lower adjusted odds of low birth weight and preterm delivery than drug users. The adjusted odds of low birth weight and preterm birth for women with an adequate number of prenatal visits were, respectively, 48 and 21% lower than for women with inadequate care. Adequate prenatal care was also associated with a 43% reduction in the odds of small-for-gestational-age. An adequate number of prenatal visits by women in this HIV cohort was associated with a significant reduction in all three adverse birth outcomes, but most had inadequate prenatal care. These data support strengthening efforts to bring pregnant, HIV-infected women into care.