HIV estimations and projections; an overview of the methodology used in 2015

Dr K.A.M. Ariyaratne Consultant Venereologist | Coordinator Strategic Information

National STD/AIDS Control Programme, Sri Lanka

Objective of this Presentation

• An Overview of the Current HIV estimation method

• What data and assumptions used for Sri Lanka during 2015

Estimated number of adults and children newly infected with HIV 2013

Middle East & North Africa25 000

[14 000 – 41 000]

Sub-Saharan Africa1.5 million

[1.3 million – 1.6 million]

Eastern Europe & Central Asia

110 000 [86 000 – 130 000]

Latin America94 000

[71 000 – 170 000]

Caribbean12 000

[9400 – 14 000]

Total: 2.1 million [1.9 million – 2.4 million]

Asia and the Pacific350 000

[250 000 – 510 000]

North America and Western and Central Europe 88 000

[44 000 – 160 000]

In 2013 there were 2.1 million new HIV infections

Why do we need HIV estimations?

• To provide HIV programme managers with estimated numbers relevant to HIV epidemic

• To use in strategic planning for prevention and care services

• For advocacy purposes: numbers infected, numbers dying

• For impact assessment e.g. Expansion of ART programme

• For global reporting/Comparing country Scenarios

Loss of patients in the AIDS treatment cascade

10th of July 2015

Software used for HIV estimations

About the Spectrum Software• Software developed by Avenir Health (Futures Institute)

and East-West Center. Updated routinely

• Guidance from UNAIDS Reference Group on Estimates Modelling and Projections www.epidem.org

• Meetings to consider issues and refine• Engage with research institutes and individuals to answer

specific questions

• Methods published in peer-reviewed journals every other year

Full model for R-Spline and R-Trend is same except for r(t) calculation

8 Source: East West Center and Futures Institute 2013

Need Quality Data and Good Assumptions

garbage in, garbage out

Outline of the Estimation Process

Demographic Data

Program Statistics

Epidemic Patterns

Surveillance and Survey Data

Demographic and Epidemic Calculations

• Mother-to-child transmission• Child model• Adult model

Prevalence / incidence trend

Results• Number HIV+• New Infections

• AIDS deaths• Need for ART

• Need for PMTCT

Step 1. Creating a projection

Step 2. ART elibgibility Criteria

Step 3. HIV Programme Statistics

• Programme Statistics

1. PMTCT data

2. ART data

3. Child treatment data

Cont., HIV Programme Statistics

Step 4. Calculating Incidence

EPP (Estimation and Projection Package) with Adult (15-49) used.

4.1 Incidence: Configuration1. Define the epidemic structure.

1. Concentrated /Low level epidemic

2. Define the sub-population characteristics1. Estimated population size 2. Whether people are likely to move in and out of this

sub-population3. Enter the estimated time (in years) that a person

spends in that sub-population.

HIV sentinel survey and IBBS data used.

4.2 Sub-populations

1. FSW2. MSM3. Drug users4. Client of FSW5. Male Remaining6. Female Remaining

4.3 Entering surveillance data

HIV sentinel survey and IBBS data used.

4.4 Sub-population sizes

4.5 Sub-population - Turn overs

4.6 Sub-population - Turn overs• Following subpopulations were included

1. Drug Users (time in DU 10 years → male remaining pop.)

2. MSM (No turn over)3. Sex worker clients (time in group 7.5 yrs →

male rem. Pop)4. Sex workers (Time in group 5 yrs → female

remain pop)5. Male remaining population (NA)6. Female remaining population (NA)

4.7 Incidence: Curve fitting• Spectrum 2015 offers four fitting methods

• R-Spline• R-Trend• EPP Classic• Workbook

• One-click fitting• Fit all

• Allows multiple projections to be fit

4.8 Models available in EPP 2015

• R-Spline (default)• Applies a set of smooth mathematical functions to give

smoother incidence curves• R-Trend

• Draws on past experience with trends in r observed in actual epidemics to produce a smooth curve

• EPP Classic• A four parameter model that is useful in low data

situations and produces an epidemic that rises and plateaus

Curve generated for MSM

Calibrating the curves

• FSW no calibration done• Clients of sex workers FSW rate down calibrated

by 0.5• MSM up calibrated by a factor of 1.2• DU no calibrations• Male remaining pop- Urban ANC prevalence used

with a down calibration by a factor of 0.5• Female remaining pop -Urban ANC prevalence

used with a down calibration by a factor of 0.5

Shapes of final curves fitted

Getting Results with Spectrum

Reported Vs. Estimated numbers

Reported Numbers - 2014

• Number living with HIV 1737 (Reported – Deaths) (53% of est.)

• New infections in 2014 228

• Deaths in 2014 26

• Adult HIV prevalence 0.03%

Estimated numbers - 2014

• Number living with HIV 3300

• New infections in 2014 <500

• Deaths in 2014 <200

• Adult HIV prevalence <0.1%

KAM Ariyaratne/ National STD/AIDS Control Programme/21.09.2015

Outputs1. HIV pop by risk groups

Outputs: 2. New HIV infections.

Too many DU new infections than actual data

Summary

• Spectrum software used in the recent HIV estimation

• Software is getting improved over the time and subjected

to very frequent software updates

• Methodology is less sensitive to very low prevalent

epidemic

• Better programmatic data, surveillance data and beter

assumptions will produce reasonable estimates

Thank you !