Aging in Sub-Saharan Africa Recommendations for Furthering Research (2006) / Chapter Skim
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3. Demographic Impacts of the HIV Epidemic and Consequences of Population-wide Treatment of HIV for the Elderly: Results from Microsimulation
3. Demographic Impacts of the HIV Epidemic and Consequences of Population-wide Treatment of HIV for the Elderly: Results from Microsimulation
Pages 92-116
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From page 92... ...
Added to this is the potential for widespread prevention and treatment programs that will have substantial impacts of their own. One of the most important and widely recognized consequences for the elderly is the creation of a large number of "AIDS orphans" -- children who lose one or both of their parents as a result of HIV-related mortality.
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From page 93... ...
In comparison to the deterministic, compartmental model used by Gregson and colleagues, this model provides a direct means through which to measure the number of orphans and the number of grandparents who could be living with orphaned grandchildren. In addition, it is able to realistically model two different types of intervention: a preventive, largely behaviorally mediated intervention and an antiretroviral treatment program, which reduces viral load and increases the time between infection and death without having other specific preventive effects.
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From page 94... ...
a population with HIV treated with both preventive and antiretroviral treatment programs. QUESTIONS Orphans can be created either through the loss of one or both of a child's parents or through abandonment by one or both parents.
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From page 95... ...
In addition to the structural changes resulting from the disease directly, prevention and treatment programs have significantly different structural effects that arise from their varied effects on the transmission and progression of HIV infections. Taking this into account, the two primary questions posed below are examined in five different treatment scenarios to ascertain the impacts of both the HIV epidemic itself and various treatment programs.
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From page 96... ...
and antiretroviral treatment programs have on the number and percentage of children who are maternal, paternal, and dual orphans after an HIV epidemic has stabilized? Numbers of Children and Grandchildren The important intergenerational consequence (alluded to above)
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From page 97... ...
and antiretroviral treatment programs have on the number and percentage of adults age 50 and older who have surviving orphaned grandchildren but no surviving children after an HIV epidemic has stabilized?
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From page 98... ...
parameterized with empirically observed mortality, fertility, and nuptiality parameters describing a rural population living in southern Zambia1 between 1950 and 1995 1The choice of the population from southern Zambia is arbitrary and simply reflects the
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From page 99... ...
The simulator models polygynous marital and both polygynous and polyandrous nonmarital pairings2 of men and women, and, within all these types of union, individual sexual intercourse events. The sexual intercourse events lead to both conceptions and the transmission of the human immunodeficiency virus, thereby tightly and accurately coupling reproduction of the population and transmission of the virus.
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From page 100... ...
A significant benefit of this architecture is that the entire history of every modeled entity is recorded permanently, a situation that allows unlimited ad hoc analysis of the resulting simulated population using the same tools one would employ to analyze similar data describing a real population. Another benefit is that any simulation can be stopped and restarted without having to employ any special logic or procedures.
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From page 101... ...
For children the rapid increase begins at about 18 months after infection, and for adults the DP begins to increase steadily from about 80 months, reaching substantial levels at about 120 months. HIV treatment programs that utilize antiretroviral pharmaceuticals to suppress viral load and extend the life of infected individuals are modeled by changing the shape and time scale of the DP indicator.
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From page 102... ...
The transmission probability utilized in both the horizontal and vertical modes of transmission is governed by the infected individual's DP indicator, allowing changes in the DP indicator -- such as those that implement the virtual antiretroviral treatment program -- to be reflected in the transmission probabilities. Infection with HIV has a number of other effects whose details are not discussed here beyond mentioning that they are implemented; see Clark (2001d)
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From page 103... ...
Widespread treatment programs are in the near future for South Africa and perhaps for other nations in the region, so it seems appropriate to let the HIV epidemics grow for three decades before instituting treatment programs in order to roughly mirror the time scale of the real epidemics and their potential treatment in Southern Africa. Future work will address the impact of treatment programs earlier and later in the life of the epidemic.
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From page 104... ...
Population with HIV Treated with Pharmacological Antiretroviral Programs A pharmacologically mediated HIV treatment program was simulated using the three HIV simulations. Starting in year 31 and running for 10 years through year 40, in each of the three HIV populations the untreated
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From page 105... ...
To keep the page count reasonable, in-depth discussion of these investigations is not possible, and consequently they are summarized briefly. After 40 years of an untreated HIV epidemic, the annual proportionate growth rate of the population is reduced to zero or below; the age structure converges on a younger, two-tiered shape with fewer young children and adults; the age-specific sex ratio attains a high of roughly 1.5 men per woman in the 45-49 age range and a low of 0.5 men per woman at ages older than 70; and the dependency ratio falls substantially.
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From page 106... ...
Maternal Paternal Dual FIGURE 3-1 Trends in the percentage of all children age 15 and younger who are orphans and adult prevalence.
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From page 107... ...
Maternal Paternal Dual D: HIV with Antiretroviral Treatment Starting in Year 31 45 50 45 40 40 35 Prevalence (percentage) Percentage of Children 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Years Since Introduction of HIV Adult prevalence (both sexes 15 -49)
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From page 108... ...
Given that most HIV epidemics in sub-Saharan Africa are less than 20 years old, big increases in the numbers of orphans may yet be coming. Looking at panel B of Figure 3-1 reveals the stunning fact that 37 percent of all children under age 15 are maternal orphans by year 40, 30 percent are paternal orphans, and 22 percent are dual orphans.
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From page 109... ...
The antiretroviral treatment program has the opposite effect on orphanhood. Immediately after the treatment begins, the total number of children begins to climb again as the HIV-mediated reduction in fertility is ameliorated, and concurrently the number of orphans begins to decline because the treatment defers HIV-related adult mortality to older adult ages that are attained after the children have lived to age 15, and existing orphans age out of the 0 to 15 age range.
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From page 110... ...
110 AGING IN SUB-SAHARAN AFRICA A: No HIV 25 450 400 20 350 300 15 Number Percentage 250 200 10 150 100 5 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Years Since Introduction of HIV Women with grandchildren and no children Women Men with grandchildren and no children Men Percentage of women with grandchildren Percentage of men with grandchildren and no children and no children B: Untreated HIV 25 450 400 20 350 300 Percentage 15 Number 250 200 10 150 100 5 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Years Since Introduction of HIV Women with grandchildren and no children Women Men with grandchildren and no children Men Percentage of men with grandchildren Percentage of women with grandchildren and no children and no children FIGURE 3-2 Trends in the number and percentage of adults age 50 and over with surviving grandchildren but no surviving children.
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From page 111... ...
111 DEMOGRAPHIC IMPACTS OF THE HIV EPIDEMIC C: HIV with "Behavioral" Treatment Starting in Year 31 25 450 400 20 350 300 Percentage 15 250 Number 200 10 150 100 5 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Years Since Introduction of HIV Women with grandchildren and no children Women Men with grandchildren and no children Men Percentage of women with grandchildren Percentage of men with grandchildren and no children and no children D: HIV with Antiretroviral Treatment Starting in Year 31 25 450 400 20 350 300 Percentage 15 Number 250 200 10 150 100 5 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Years Since Introduction of HIV Women with grandchildren and no children Women Men with grandchildren and no children Men Percentage of women with grandchildren Percentage of men with grandchildren and no children and no children FIGURE 3-2 Continued.
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From page 112... ...
At the same time, the number and percentage of adults age 50 and older with surviving grandchildren but no surviving children begins to rise. Because the total number of adults age 50 and older is declining while the number with surviving grandchildren but no surviving children is rising, the percentage with surviving grandchildren but no surviving children rises very quickly.
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From page 113... ...
In contrast, the antiretroviral treatment program has an immediate and very positive impact on this indicator, panel D of Figure 3-2. The number of adults age 50 and older stabilizes because HIV-related adult mortality is deferred, and the number of adults age 50 and older with surviving grandchildren but no surviving children also stabilizes for the same reason.
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From page 114... ...
The situation grows even grimmer when viewed from the point of view of the elderly themselves, with the result that nearly 25 percent of women older than age 50 potentially live with surviving grandchildren but no surviving children after 40 years of an HIV epidemic. Taken together with the impact of HIV on the age-specific sex ratio, which after 40 years of an epidemic results in two-thirds of the population age 50 and older being female, the final result is that fully one-fifth of the total population over 50 years of age will potentially be in a position of some obligation to care for grandchildren.
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From page 115... ...
Again, because the simulated treatment lasted only 10 years, there was not sufficient time to see the rebound of HIV-related mortality as the deferment expired and HIVrelated mortality began to reassert itself at a new level slightly lower than what it had been before the treatment began -- because of the reduction in incidence brought about by the suppression of viral load and lowered transmission probability. In general it appears that some mixture of the two types of treatment program is best; the combined approach often leads to a smoother result with less dramatic short-term changes, and often the two complement each other.
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From page 116... ...
. The im pact of HIV/AIDS on adult mortality in South Africa.
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