*! version 5.4 12Mar2020 for version 5.30 of aidsproj

help for aidsprojVersion 5.30, 15Feb2020
dialog:

aidsproj: AIDS Burden Projection

aidsproj
[if exp]
[using filename ]
,
uptake:(pa_varname|pa_coef)
[options]

Description

aidsproj uses input data on a cross-section of countries in the
year prior to the "vintage year" of the data
to project several measures of the future disease and fiscal burden of
the AIDS epidemic on individual countries and on specified aggregates of
those countries. The program has one "required option",
sets of options to describe patient recruitment,
the health benefits of treatment, the costs of treatment,
the incidence of new infections and a set of output options.

This program is part of the AIDSCost package. By running this
program once for a "baseline" or "counterfactual" scenario and once
for each of K-1 alternative scenarios, the user can then use the
companion program aidsdif to estimate the "Incremental Cost
Effectiveness Ratio" of each of the K-1 against the baseline.

aidsproj models the epidemiological and health consequences of HIV/AIDS
policy, including alternative treatment, circumcision, vaccination and behavioral
change interventions. While aidsproj has built-in defaults and user-selected options
to model the cost of antiretroviral therapy (ART), constructing a cost-function
to characterize the future fiscal requirements of non-treatment options,
such as circumcision, vaccination and behavioral change, must be addressed
outside the program.

Options

The following presentation of options is in the order they appear on
tabs on the aidsproj dialog.

Options on the "Main" tab

Data input options

Projection options

Options on the "ART Uptake" tab

ART initiation options

ART therapeutic effectiveness options

Options on the "Second line/TasP" tab

Second line treatment options

Secondary prevention options (TasP)

The disinhibition effect of treatment

Options on the "Exogenous Incidence" tab

Baseline risk parameter

Exogenous incidence options

Options on the "Primary Prevention" tab

Male circumcision options

Hypothetical vaccination options

Primary prevention `effort' options

Options on the "Cost" tab

Non-drug cost options

Drug cost options

Options on the "Saving and Weights" tab

Saving options

Weighting countries in summary results

Options on the "Output" tab

Output options

Advanced options not in the aidsproj dialog

Main

using filename Optionally specify an input data file.
The file name may include a directory path. If no input file is specified,
aidsproj attempts to use the data in memory as the input data file.

if exp Optionally restrict consideration to a group of countries
which meet a logical criterion such as with a GDP below some maximum value.
Not a good substitute for selecting a specific country or several countries
with the countries(country_list) option or for selecting a region with the
regions(region_list) option. Rarely used.

Input options

vintage(vyear) Vintage of data in the Stata dataset in memory or loaded with
using filename. Default is 2018.

complete Restrict computations to countries which have complete
data. This option cannot be selected with the impute option.

impute Attempt to impute the missing values of variables for
countries for which the data is not complete.
This option cannot be selected with the complete option.

Projection options

takeoff(tyear) Specifies the first year for which
projections are displayed. Default is 2017.
Maximum is 2050.

horizon:(hyear) Specifies the last year to which
projections are computed. Default is 2030. Maximum is 2100.

ART Uptake

Initiation options

uptake(pa_varname|pa_coef) The proportion of eligible untreated HIV+
adults who are initiated on treatment in each future year of the projection.
The parameter can be specified as a proportion between zero and one, pa_varname,
or as a variable in the input data, pa_varname. In the latter case,
the value can vary by country. Required option.

cd4(integer) Median CD4 count at treatment initiation.
Default is 130. Unless overridden by the user's specification of one or more of the
Therapeutic options below, this parameter determines the first-year death-rate,
adrate1, the rate at which HIV+ convert to ART eligibility, erate,
and the death rate among ART eligible not on ART, ndrate.

Therapeutic options

adrate1(proportion) First year death rate on 1st
line ART. Default is a decreasing function of the cd4(integer)
option, but can be overidden by explicitly specifying
the adrate1 proportion. Must be between zero and one.

adrate2(proportion) Subsequent annual death rate on
1st line ART. Default is 0.04. Not affected by choice of the
cd4(integer) parameter. Must be between zero and one.

erate(proportion) Rate at which HIV+ convert to
be eligible for ART. Default is an increasing function of the cd4(integer)
option, but can be overidden by explicitly specifying the erate proportion.
Must be between zero and one.

ndrate(proportion) Death rate among ART eligible
not on ART. Default is a decreasing function of the cd4(integer)
option, but can be overidden by explicitly specifying the ndrate proportion.
Must be between zero and one.

2nd Line/TasP

2nd line options

strtcov2(proportion) Proportion of adults receiving
antiretroviral medication who are on second-line therapy at the
beginning of the projection period. Default for any country is a regional constant.
Must be between zero and one.

trgtcov2(proportion) Of those who fail first-line treatment
during the projection period, this option specifies the target
proportion to initiate second-line treatment.
Default is 0.50. Must be between zero and one.

strtyr(year) Starting year of coverage
with 2nd line therapy. Default is one year before vintage(year).

trgtyr(year) Year target level trgtcov2(proportion) to be
reached with 2nd line therapy. Default is 2050.

bdrate(proportion) Annual death rate on 2nd line ART. Default is 0.04.
Must be between zero and one.

Secondary prevention

fp(proportion) The proportion of transmission that occurs after
individuals might plausibly start treatment. Default is 0.7.

gp(proportion) The reduction in transmission among those on treatment.
The trial
HPTN 052
found this effect to be 0.96. The default here is 0.8.

Disinhibition

maxdt(proportion) The disinhibition effect of treatment
on the risk behavior of the treated.
Must be between -0.5 and 0.5, inclusive.
Rarely used.

maxdu(real) The disinhibition effect of treatment
on the risk behavior of the untreated.
Must be between -0.5 and 0.5, inclusive.
Rarely used.

Exogenous incidence

Baseline risk

ir0(proportion) Incidence rate among those engaged in high risk
behavior at the beginning of the projection period. This group typically
includes sex workers, soldiers, policemen and truck drivers.
Default is 0.20.

Exogenous incidence

iexog Incidence to follow an exogenous trend controlled
by the parameter incmult. On the `Exogenous Incidence' tab of the
dialog box, check the box entitled `Number of new infections to follow an exogenous trend'.
The default, specified when iexog is omitted, is for incidence to
be affected by the prevalence of HIV and by ART coverage.

incmult(real) Incidence in future years is
mechanically computed as this multiple of incidence the previous year.
Default is 0.97. This parameter is ignored unless the option iexog
is specified. Must be a real number greater than zero.

Primary Prevention

Male circumcision

mincp(proportion) Proportion of adult men circumcised in
the starting year of a circumcision drive ,cstrtyr(year), and
in prior years from the beginning of the simulation. The user should
specify a value for this starting level of male cirucmcision that
reflects the ethnographic literature on the country or region being
modeled. Must be between zero and one.
Note that this parameter does not appear on the aidsproj dialog.
Default is 0.1.

maxcp(proportion) Target proportion of adult men circumcised in
the target year ctrgtyr(year) and in subsequent years to the planning
horizon(year)}. Must be between zero and one. Default is 0.1.

cstrtyr(year) Start year for scaling up male circumcision
from its starting value, mincp(proportion), to its maximum value,
maxcp(proportion).
Note that this parameter does not appear on the aidsproj dialog.
Default is 2020.

ctrgtyr(year) Target year for reaching the target prevention
"effort" of maxcp(proportion). The trajectory of effort increases
linearly from mincp(proportion) in the year cstrtyr(year)
to maxcp(proportion) in the year ctrgtyr(year)
Note that this parameter does not appear on the aidsproj dialog.
Default is 2030.

csp(proportion) Protective effect of male circumision for men.
Must be between zero and one.
Note that this parameter does not appear on the aidsproj dialog.
Default is 0.5.

Hypothetical vaccination

minvp(proportion) Starting proportion of adults vaccinated
with an HIV vaccine in the starting year of a vaccination drive,
vstrtyr(year)}. This parameter cannot be asjusted by the user.
It is always equal to zero.

maxvp(proportion) Target proportion of adults vaccinated
with an HIV vaccine in the target year, vtrgtyr(year)}.
In 2020, no vaccine has yet been approved for use, so this
intervention is hypothetical and should be modeled as starting
in the future.
Default is 0.

vstrtyr(year) Start year for scaling up HIV vaccination
from its starting value of minvp=0 to
the target proportion vaccinated of maxvp(proportion).
In 2020, no vaccine has yet been approved for use, so this
intervention is hypothetical and should be modeled as starting
in the future.
Default is 2025.

vtrgtyr(year) Target year for reaching the
target proportion vaccinated of maxvp(proportion).
Default is 2030.

ve(proportion) Effectiveness of the vaccine as a proportion
of infections averted. A value of 1.0 for this parameter would
be approriate for a vaccine that is 100% effective.
Default is 0.6.

Prevention `effort'

minep(proportion) Initial intensity of prevention effort
before and during the starting year, pstrtyr(year)}. Default is 0.

maxep(proportion) Target intensity of prevention effort in
the target year, ptrgtyr(year)} and in subsequent years
to the planning horizon(year)}.
This parameter can be used to model any behavioral prevention intervention
that is applied to all sexually active adults. Examples include
condom promotion, female empowerment, girls' education, PrEP and
individual or couple counseling at home or in a facility.
To increase this parameter above zero requires
positing an intervention (or package of interventions)
with an impact of the chosen magnitude.
Setting this parameter to 1.0 prevents all new infections.
Must be between zero and one. Default is 0.

pstrtyr(year) Start year for scaling up prevention "effort"
from its starting value, minep(proportion), to its maximum value,
maxep(proportion). Default is 2020.

ptrgtyr(year) Target year for reaching the target prevention
"effort" of maxep(proportion). The trajectory of effort increases
linearly from minep(proportion) in the year pstrtyr(year)
to maxep(proportion) in the year ptrgtyr(year)
Default is 2030.

Cost

Non-drug cost

Non-drug cost is the sum of non-drug fixed cost (nonrxcaf) and non-drug variable cost (nonrxcav).

Total non-drug fixed cost.
The total non-drug fixed cost estimates the administrative and overhead cost of operating
an AIDS-treatment program. In a given year, this non-drug fixed cost
is defined as the following function of the total number of patients
on ART in a country:

nonrxcaf = exp[(ln(ndaf) - scale*6.91) + scale * ln(art)]

where ndaf and scale are
user-selectable options defined below and
art is the total number of patients on ART, which is a variable
projected by the model.

ndaf(real) Average fixed non-drug cost per patient
on treatment.
Default is 750 (dollars per patient-year).

scale(real) Elasticity of average non-drug cost with scale at
number on treatment of 1,000. Defualt is -0.146.

Total non-drug variable cost.
The total non-drug variable cost estimates the cost of the inpatient
and outpatient health services used by the average ART patient
in a given year in a given country. While the cost per service unit
varies by the country's GNI per capita, the number of units of each service
used will decline to small values as the CD4 count at initiation
is increased. In this model, the total non-drug variable cost
is defined as the following function of the total number of patients
on ART in the country:

nonrxcav = art[hsbedn*hsbedc + hsvstn*hsvstc]

where hsbedn and hsvstn are user-selectable options
defined below and art is the total number of patients on ART, which is a variable
projected by the model.

hsbedn(real) Average number of hospital bed-days
per patient on treatment per year. Default is 1.96.
This value is multiplied by an estimate of the cost of
a hospital bed-day given by the equation

hsbedc = exp[-2.75 + 0.77 * log(GNIPC)]

where GNIPC is gross national income per capita
for the projection year. Source: Adam and Evans (2006)

hsvstn(real) Average number of outpatient visits
per patient on treatment per year. Default is 9.5.
This value is multiplied by an estimate of the cost of
an outpatient visit given by the equation

hsvstc = exp[-4.8 + 0.89 * log(GNIPC)]

where GNIPC is gross national income per capita
for the projection year.
Source: Adam et al. (2008)

cost(function|revert) Setting the cost option
to either of its two possible non-blank values causes aidsproj to use one of two
previous methods for cost estimation. Default is to use the functions
described above. The options cost(function) and
cost(revert) are rarely used.

Drug cost

Drug cost is the sum of the cost of first-line drugs [rxc1 * (a1+a2)] and second-line drugs [rxc2 * b].

First-line drug cost per first-line patient.
The first-line drug cost per first-line patient in a given country and year
is defined as the following function of the variable lgtrxc1:

rxc1 = (rxc1ub * exp(lgtrxc1) + rxc1lb)/(exp(lgtrxc1) + 1)

where rxc1ub and rxc1lb are
user-selectable options defined below and
lgtrxc1 defined as lgtrxc1 = -6.9 + 1.02 * ln(GNI per capita).

rxc1lb(real) The lower bound of the unit cost per patient-year
of first-line drugs in a country of low income. Default is 88.

rxc1ub(real) The upper bound of the unit cost per patient-year
of first-line drugs in a country of upper middle income. Default is 261.

Second-line drug cost per second-line patient.
The second-line drug cost per second-line patient in a given country and year
is defined as the following function of the variable lgtrxc2:

rxc1 = (rxc2ub * exp(lgtrxc2) + rxc2lb)/(exp(lgtrxc2) + 1)

where rxc2ub and rxc2lb are
user-selectable options defined below and
lgtrxc2 defined as -10.4 + 1.34 * ln(GNI per capita).

rxc2lb(real) The lower bound of the unit cost per patient-year
of second-line drugs in a country of low income. Default is 819.

rxc2ub(real) The upper bound of the unit cost per patient-year
of second-line drugs in a country of upper middle income. Default is 2634.

Saving and Weights

saving(stub[,replace]) Specify the stub of a filename. This stub
will appear as the prefix of the names of all the files created
by this run of aidsproj. If these files are to replace
pre-existing files with the same names, specify the replace
option.

outpath(path) Specify the directory where aidsproj
will save all the files generated by this run. If the
directory is called myoutput, the directory can
be specified by its full path or, if it is a subdirectory
of the current working directory, by a relative path.
See filename for examples of paths specific
to the Windows and Mac operating systems.

weights(varname) Specify the name of an existing
variable for -aidsproj- to use to weight averages over
multiple countries. This option is not relevant
if the user is projecting the results for a single country.
Default is to weight multi-country averages by the
number of ART patients as measured by the variable
art.

Output

weo

countries(cabs) Specify the three-letter country code
(i.e. the country abreviation or cab) for
one or more specific countries for which projections are desired.
A drop-down menu in the dialogue box for this option allows
the user to select countries by their full names and then
fills in the three-letter country code in the countries(cabs)
option. A separate set of tables and graphs will be produced
for each country.

regions(rabs) Specify the three-letter region code
(i.e. the region abreviation or rab) for
one or more specific regions for which projections are desired.
A drop-down menu in the dialogue box for this option allows
the user to select regions by their full names and then
fills in the three-letter region code in the regions(rabs)
option. A separate set of tables and graphs will be produced
for each region.

world Generate aggregate world totals for all countries included
in the data. Rarely used.

gr7|graph Specifying one of these two options is required to produce
any graphics output. Choosing option gr7 is somewhat faster
computationally but less accurate. Choose option graph for
production quality graphic output.

grcombine Present four of the graphs as the four panels in a single
chart. When the option weo is selected, the graph of
treatment coverage rates is omitted to make room for the graph
of "affordability".

norescale By default, aidsproj rescales the quantities
graphed on vertical axes in units of thousands or millions or billions,
as the program best guesses will be aesthetically fitting. To
supplress this function, specify the option norescale.
Rarely used.

legend(legend_opts) Legend suboptions
are passed to the graph commands and override aidsproj's
default legend options.

titlen(titlen_opts) Replaces standard
title for quantity graphs. Specifying " " suppresses the title.

titlec(titlec_opts) Replaces standard
title for cost graphs. Specifying " " suppresses the title.

titlep(titlep_opts) Replaces standard
title for percent discretionary graphs. Specifying " "
suppresses the title.

titlee(titlee_opts) Replaces standard
title for percent expenditure graphs. Specifying " " suppresses the
title.

subtitle:(subt_opts) Replaces standard
subtitle for all graphs. Specifying " " suppresses the
subtitle.

Advanced options

putexcel Specifying this option instructs aidsproj
to write projection results to a spreadsheet file which can be opened with
Microsoft Excel or compatible programs. The spreadsheet file name,
like the names of other files saved by aidsproj,
is determined by the saving(stub[,replace]) option.

logout Specifying this option instructs aidsproj
to create a separate log file for each discrete region or country
specified by the options regions(region_list)
or countries(country_list).

Discussion

Input data file (on the `Main' tab of dialog)

The program must be fed a cross-country panel dataset containing
specific variables. The program assumes that this file will be supplied
by the using filename specification on the command line.
That data set can be resident in memory when the program is called
or can be specified by using filename.

Uptake is a required option (on the `ART Uptake' tab of dialog)

The program aidsproj has only one required "option",
uptake:(pa_varname|pa_coef) , which
specifies the speed at which the countries in the projection will
increase their coverage of the unmet need for antiretroviral treatment.
The speed of uptake is specified as a "partial adjustment coefficient"
sigma, where 0 <= sigma <= 1 gives the proportion of
the unmet need for treatment who are enrolled for the first time
in antiretroviral therapy each year. "Unmet need" is defined as those
adults age 15-64 who are eligible for treatment (as defined by the
parameter cd4 on the "ART Uptake" tab of the dialog box) and
not yet receiving treatment.

The model assumes that, once enrolled in treatment,
a patient has a lifetime entitlement to at least first-line treatment.
By choice of the parameters strtcov2, trgtcov2 and bdrate,
the user can adjust the degree to which this entitlement
extends to second-line treatment.

Those familiar with the "partial adjustment" or the
"adaptive expectations"
model in applied econometrics will recognize
that sigma is related to the partial adjustment coefficient lambda
in that model by sigma = (1 - lambda).

The uptake parameter sigma is constant over time within
each country. It can be provided either as a variable pa_varname
which contains a single value for each country or as a constant
pa_coef which is then applied to all countries. For example,
specifying uptake(0.95) instructs aidsproj
that, in addition to treating all ART patients surviving from
previous years, all countries in the projection will in
each future year extend treatment to 95 % of those are eligible
for treatment and not yet on treated. Those eligible for treatment
are adults aged 15-64 who are HIV-infected with a CD4 count less than
the user-selected parameter cd4.

Country inclusion criteria (on the `Main' tab of dialog)

complete|impute User can optionally sepcify either the
complete option or the impute option, but not both. Using
neither option allows aidsproj to perform some minor, relatively
innocuous imputations in order to add a few countries to the
projections. The complete option suppresses the countries for
which these innocuous imputations are required. The impute option
authorizes aidsproj to perform more daring imputations in order to
include more countries. As part of its routine output, aidsproj
tabulates the sample by the countries that are "complete" before any
imputations and those that are included by imputation.

The user can select subsets of countries for inclusion in global or
regional aggregates by using the if exp criterion.

If no output options are specified, the program uses default
values of all the optional parameters, computes projections of the key
variables until the default horizon of 2030 and halts. If the user
specifies the option countries(clist), then for each country in
clist the program presents the projection results in tabular form.
If the user specifies the option world or regions(rlist),
the program computes the totals or averages for the specified
aggregate(s). Quantity or cost/expenditure projections are summed across
the specified group of countries while percentages or rates are
averaged. Averages are weighted by the number of people receiving
antiretroviral treatment in the given year in the respective countries
(not by their number of HIV infected, total populations or GDP).

The three default output sets are (1) the epidemiological
projections of the number of people under treatment, in need of
treatment and dying in each future year until the projection horizon;
(2) the average unit cost of treatment and the total cost of treatment;
(3) the proportion of annual expenditure that treats ongoing patients
(called the "entitlement") and the proportion that treats new patients
(called "discretionary"). If the weo option is specified, a fourth
set of projections compares the projected total expenditures on ART to
three projected national budgets which are projected under a no_ART
scenario using the
2007 World Economic Outlook.
The three budget categories used as comparators are total health
expenditures, central government public health expenditures and total
central government expenditures.

Saving option

saving:(stub, [replace]) Specifies the
filename for the projections data file which the program then saves in
STATA's dta format, which is also the stub of the filename for
saved graphics files. If saving(stub,[replace]) is omitted,
neither the data file of projections nor
the gph files are saved.

Examples

The following example generates projections of the worldwide
burden of the epidemic to the year 2030, using version 7 graphics. By
selecting the partial adjustment coefficient to equal 0.95, with the
option uptake(0.95), the scenario assumes that all
countries in the world will expand at 95 % of unmet need for ART each
year. Specifying the complete
option excludes from the calculations countries with incomplete data.
(The alternative to complete is impute).
Specifying iexog).
imposes an exogenous change in the incidence rate.
The default exogenous change is a decline of 5% per year.

aidsproj using aidssub2007, uptake(.95) iexog world gr7 grcombine complete

The following example changes only one epidemiologic
parameter, the assumption regarding the change in the rate of new cases
of HIV, or the incidence rate. Instead of the default assumption which
is that the number of new cases would decline by 5 % each year, this
example assumes that the rate of new cases would decline dramatically in
2007 by 90 % to only 10 % of its 2006 level and then continue to decline
by another 90 % every year. In other words it assumes that the rate of
new cases declines asymptotically to zero.

aidsproj using aidssub2007, uptake(.95) iexog incmult(.10) world gr7 grcombine complete

The following example produces the identical epidemmiological
predictions as the previous one, but presents different output. In
addition to output on all countries, it specifies output on the
individual countries in the World Bank's South Asia region, on the South
Asian Region as a whole and also, for comparison, on the Sub-Saharan
African region as a whole. All nine graphs are presented and saved, with names
beginning with the character string: "adj95_weo".

aidsproj using aidssub2007, uptake(.95) iexog incmult(.10) graph grcombine complete weo world countries(BGD BTN IND LKA NPL PAK) regions(SAS SSA) saving(adj95_weo, replace)

Author

Mead Over,
Center for Global Development, Washington, DC 20036 USA. Email:
MOver@CGDev.Org if you observe any
problems.

References

Adam, Taghreed and David B Evans,
"Determinants of variation in the cost of inpatient stays versus outpatient visits in hospitals: a multi-country analysis."
Soc Sci Med. 2006 Oct;63(7):1700-10.
PubMed link

Adam, Taghreed, S. Ebener, Ben Johns and David B Evans,
"Capacity utilization and the cost of primary care visits: implications for the costs of scaling up health interventions."
Cost Eff Resour Alloc. 2008 Nov 13;6:22. doi: 10.1186/1478-7547-6-22.
PubMed link

Over, M., "Prevention Failure: The Ballooning Entitlement
Burden of U.S. Global AIDS Treatment Spending and What to Do About It"
Working Paper 144,
Center for Global Development, 2008.

Over, M., "Opportunities for presidential leadership on AIDS:
From an "Emergency Plan" to a Sustainable Policy," in N. Birdsall (ed.),
The White House and the World: A Global Development Agenda for the Next US President,
Center for Global Development, 2008, Chapter 11, pp. 299-326.

Over, M., "AIDS Treatment in South Asia: Equity and
Efficiency Arguments for Shouldering the Fiscal Burden When Prevalence
Rates Are Low"
Working Paper 161,
Center for Global Development, 2009.

McCarthy, O. and M. Over,
"Projecting the Future Budgetary Cost of AIDS Treatment in Poor Countries: A Manual for the AIDSCost Computer Programs",
Center for Global Development, 2009. This manual applys to the versions of the AIDSCost model
before it was revised to incorporate the prevention effects of AIDS treatment. The PDF can be downloaded
here.

Over, M., Achieving an AIDS Transition: Preventing Infections to Sustain Treatment,
Brookings,
2011. Available from
Amazon
or a free PDF can be downloaded
here.

Over, M. and G. Garnett, "Treatment Initiatives to Reduce the Impact
of the HIV/AIDS Epidemic: Assessment", in Bjorn Lundberg (ed.)
Smarter ways to invest in ending HIV in Sub-Saharan Africa
Cambridge University Press, 2012. Available from
Amazon.