designing equitable antiretroviral allocation strategies in resource-constrained countries
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Designing Equitable Antiretroviral Allocation Strategies in Resource-Constrained Countries. David P. Wilson Sally M. Blower Presented by Harry Chang April 7 th , 2010. What is this about?. 2 Biomathematicians: UCLA AIDS Institute - PowerPoint PPT PresentationTRANSCRIPT
David P. Wilson
Sally M. Blower
Presented by Harry Chang
April 7th, 2010
2 Biomathematicians: UCLA AIDS Institute
Topic: Equitable distribution of ARV in resource-constrained countries
Proposal: Mathematical model for achieving OEAS
Focus: KwaZulu-Natal province of South Africa
ARV Allocation DecisionBackgroundExperimental OutlineMethodsResultsBest StrategyFuture ExtensionsAuthors’ Conclusions
Caveats & Shortcomings
Discussed extensively: ARV for HIV/AIDS
Last presentation: ending note
Novel scientific approach
Interesting proposed resolution
ARV therapy expensive: barriers to providing essential medicines (eg. patents protecting IP), long-term treatment etc.
Cannot afford to treat all afflicted individuals
How to make decision?
EpidemiologyPreferential:
MenPregnant womenChildrenSickestHighest efficiencyMilitaryDominant ethnic group…
LotteryPeris, S.J. On a never-ending waiting list: toward equitable access to anti-retroviral treatment? Experiences from Zambia .
Health and Human Rights, 8, 76-102.
McGough LJ, Reynolds SJ, Quinn TC & Zenilman JM. Which patients first? Setting priorities for antiretroviral therapy where resources are limited. Am J Pub Heal, 95, 11173-1181.
1) All similar cases be treated alike
2) Utilitarian: maximize overall social benefits
3) Egalitarian: Equal distribution to different groups
4) Maximin: Prioritize least advantaged individuals
Ethical: Equality“Each individual with HIV has an equal chance
of receiving ARV”
Intention: mathematical model of treatment accessibility & equity objective function OEAS
South Africa epidemic (12% of population)
KwaZulu-Natal = largest province
Population: 9.4 million
highest HIV-positive (21% of all South Africa)
Total HCF: 54
Photo source:
Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
April 2004
17 HCF in KwaZulu-Natal for ARV Roll-out
Variable distance between communities & HCFSpatial distribution diverse heterogeneity,
unequal accessibility to ARV
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Photo source:
Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Intention: Determine ARV OEAS for KwaZulu-Natal
Examine parameters 1) Changing catchment region of HCF
20km OR 40km OR 60km2) Number of HCF
1 OR 17 OR 54
Compare to1) All ARV to Durban2) Equal ARV to 17 HCF (current government
plan)
ARV available for distribution only treat 10% of infected
Catchment region: do not know hence approx 40km
Distance from community to HCF is determinant of whether patient has access to treatment
HIV prevalence: urban = 13%, rural = 9%Only 51 communities in KwaZulu-Natal
Population > 500
Accessibility = how likely a patient will travel to a HCF to receive ARV
# Patients go to HCF: increase with # of patients, decrease with distance
Considered:# people in communityTreatment Accessibility function
Gaussian Radius of catchment region
Weighting function: distance btw community and HCFLongitudeLatitudeRadius of EarthAngles (rad)
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Spatial relation of HCF to neighbouring communities
ARV supply
Effective demand for each HCFLongitudeLatitude
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Purpose: find optimal equitable allocation strategy
Catchment region sizeNumber of HCF Total number of ARV Amount of ARV to each HCF
Precautions:Total ARV supplied = Total ARV distributed# ppl treated <= # HIV++ number of ARV to each HCP
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Majority ARV to HCF in Durban
2 non-Durban HCF have 5-15%
Other non-Durban HCF have <5%
When using current South Africa ARV roll out plan of 17 HCF
Compare using fixed 40km catchment regionIdeal: 10% patients receive ARV at each HCFCompare inter-quartile range:
1) All ARV to Durban:Small inter-quartile range; Unfair
2) Equal ARV to 17 HCF:Large inter-quartile range: 0.025-42% unequal
access1) 3) Authors’ OEAS:
Doesn’t necessarily deliver 10% to all patientsSmall inter-quartile range 0.011 – 10% treated
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Authors’ OEAS not perfect but gives best equality of ARV distribution
Equality improves SUBSTANTIALLY with either
# HCF used is more important than catchment size27 HCF
1) 20km 88% 2) 40km 91%3) 60km 96%
54 HCF1) 20km 90%2) 40km 94%3) 60km 99%
Photo source: Wilson DP, Blower SM (2005) Designing equitable antiretroviral allocation strategies in resource-constrained countries. PLOS Medicine. DOI: 10.1371/journal.pmed.0020050
Increase # HCF, SIGNIFICANTLY increase treatment accessibility
Propose: Increase in catchment region by increasing transportation
Use all 54 HCF, each with catchment region of 40-60km to maximize ARV distribution
Nigeria: Mobile clinic
Increase catchment region:Challenge: improve transportation costly
Use all 54 HCFAdvantage: existing infrastructureChallenge: training costly
Data: distance patients willing/able to travel to HCF
Data: factor in travel ease for all communitiesDifferent weighting function based on road
infrastructure, availability of transportation etc.
Authors chose equality as objective Other ethical ARV allocation strategies present
Need even access from national to grass root levelProportion to province, HCF, groups of individual
If uneven accessSocial, political structure destroyedIntra-state, inter-state conflict
1) Behavioural core groupsEg. sex workersChallenge: fraud to receive priority treatment
2) Highest viral loadAdvantage: easy to identify
3) Those s.t. reduce future epidemic impactAdvantage: potentially decrease future
epidemicDisadvantage: disregard current patients
(unethical?)
Our OEAS can be used by any resource-constrained country and highly recommended
Each nation has to decide on priorities of ARV distributionObjective function can be modified but OEAS
still apply
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