Estimates


Population size estimation

Often, disease surveillance systems count cases or conduct repeated cross-sectional surveillance to measure changes in the prevalence of a disease or behaviour — the percentage of a given population that is infected with HIV for example, or the percentage of drug injectors that has no access to clean needles. We say these data are useful for planning purposes, but in truth they are often not, in large part because we have no idea of how many people they apply to. If we discover that 90% of injectors have no access to clean needles, for example, we can’t plan effective needle distribution systems until we know whether that means 90 people (out of a total of 100 injectors) or 9,000 (out of a total of 10,000).

Ternyata staff were involved in developing the first systematic estimates of populations at risk for HIV in a developing country, in Indonesia in 2002. The methods have since been refined and used extensively in other countries with HIV epidemics concentrated among drug injectors, the sex trade and gay men. These countries include China, Russia and Nepal.

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Estimating the size of populations at risk for HIV: Issues and methods (.pdf 2.09Mb)
WHO/UNAIDS/Family Health International, Bangkok and Geneva, 2003

Recognizing the increasing importance of accurate population size estimates in planning and evaluating HIV interventions, this guide for the first time brings together various methodologies that can be used to estimate the size of populations with behaviours that carry a high risk of HIV infection. It discusses the strengths and weaknesses of various methods, and is filled with examples and training exercises
Full URL: http://www.ternyata.org/wp-content/uploads/2010/02/population_size_estimation.pdf

Estimating HIV infection in a concentrated epidemic: Lessons from Indonesia (.pdf 484kb)

UNAIDS, Geneva, 2003

Part of the UNAIDS Best Practice collection, this account details the process and the results of the first attempt to derive estimates of HIV infection based on rigorously documented, data based estimates of the size of at-risk populations in Indonesia. Indonesia, the world’s fourth most populous nation, was the first country with a concentrated epidemic to base national estimates on provincial-level data.
Link URL: http://www.ternyata.org/wp-content/uploads/2010/02/Indonesia_estimates_process.pd

Estimating the number of people at risk for HIV and living with HIV in China in 2005: Methods and results (.pdf 108kb)
Fan L, Ning W, Wu ZY et al. Sexually Transmitted Infections, 2006 82: iii87 – iii92

Description of the process by which the number of injection drug users, sex workers, clients of sex workers and men who have sex with men in China was estimated. Estimates for the number living with HIV are also described. The results were significantly lower than previous estimates: this paper explains why.
Full URL: http://www.ternyata.org/wp-content/uploads/2010/02/china_estimates.pdf

Estimating the number of drug injectors in Indonesia (.pdf 86.4)
Pisani E. International Journal of Drug Policy, 2006 17 (1): 35-40

Detailed description of the first attempt by a developing country to make estimates of the number of drug injectors for each province nationwide.
Full URL: http://www.ternyata.org/wp-content/uploads/2010/02/idu_estimates_indonesia.pdf

Disease estimates

In most countries outside of East and Southern Africa, most HIV cases are found in limited sub-populations with fairly well defined risk behaviours. Reliable estimates of the number of people living with HIV, as well as the numbers newly exposed to infection or newly infected, depend on having an idea of who is in the denominator.

Once estimates of population sizes have been made using the methods described above, we can begin to estimate how many are infected and at risk.

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Estimating the number of people at risk for HIV and living with HIV in China in 2005: Methods and results (.pdf 108kb)
Fan L, Ning W, Wu ZY et al. – Sexually Transmitted Infections, 2006 82: iii87 – iii92)

Description of the process by which the number of injection drug users, sex workers, clients of sex workers and men who have sex with men in China was estimated. Estimates for the number living with HIV are also described. The results were significantly lower than previous estimates: this paper explains why.
Link URL: http://www.ternyata.org/wp-content/uploads/2010/02/china_estimates.pdf

Back to Basics in HIV Prevention: Focus on Exposure (.pdf 115kb)
Pisani E, Garnett G, Brown T et al. – British Medical Journal, 2003; 326: 1384-1387

This paper argues that HIV prevention programmes often ignore the evidence collected by national surveillance systems, and are guided instead by fashion, donor priorities, or a misplaced sense of “equity”. Using very simple models, it shows that more infections could be prevented if efforts were refocused on the situations in which HIV infected and uninfected individuals were most likely to be exchanging body fluids. A doctoral thesis develops this argument at very much greater length using the specific example of Indonesia; click here to download a pdf version. (.pdf 4.6 MB)
Full URL: http://www.ternyata.org/wp-content/uploads/2010/02/Back_to_Basics_in_HIV_prevention.pdf


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