Academic journal article Bulletin of the World Health Organization

Monitoring the Scale-Up of Antiretroviral Therapy Programmes: Methods to Estimate Coverage

Academic journal article Bulletin of the World Health Organization

Monitoring the Scale-Up of Antiretroviral Therapy Programmes: Methods to Estimate Coverage

Article excerpt

Introduction

On 1 December 2003, WHO in partnership with UNAIDS launched the "3 by 5" initiative, which aimed to mobilize the world to provide antiretroviral therapy (ART) to 3 million people in low- and middle-income countries by the end of 2005. (1) The 3 million target was based on an analysis published in 2001, which indicated that this figure would correspond to about a 50% coverage of adults in need of treatment. (2) At the end of 2003, an estimated 400 000 people in low- and middle-income countries were on treatment and almost half of those were living in Latin America. ART coverage in Africa and Asia was below 5%.

Estimation of health service coverage--such as the Millennium Development Goal indicators of measles vaccination and skilled birth attendant coverage --is mostly derived from population-based household sample surveys. If no such data are available, coverage has to be calculated from an estimate of the numerator (i.e., the number of people receiving or using the service) and the denominator (i.e., the estimated number of people in need of such services). Even for well-established programmes such as immunization and tuberculosis control, this method may give unsatisfactory results, because of under-reporting, over-reporting or methodological and technical problems with accurate estimation of the denominator.

Population-based surveys, however, are not a suitable data source for the estimation of ART coverage, since population prevalence is relatively low, reporting biases are likely, and there are ethical issues associated with stigma and discrimination. Estimates of the number of people on ART and the corresponding coverage are based on service statistics and estimates of the need for treatment) In this paper, we describe the procedures and methods used to monitor progress towards "3 by 5" and provide an estimate of treatment coverage achieved by the end of June 2005. For the first time, children are included in overall estimates of the number of people in need of treatment.

Estimating the number of people on antiretroviral therapy

To estimate the number of people on treatment, we have used data from most recent report received from the Ministry of Health or WHO country office, or other sources from within countries. Usually, countries keep track of the number of sites providing ART and the number of people on treatment in those sites. At the end of each calendar year, data are requested by WHO from all 152 World Bank classified low- and middle-income countries. For the mid-2005 update, we focused on obtaining data from the countries with the largest unmet need for treatment. (4) Overall, updates were received from 35 of 152 low- and middle-income countries, which accounted for 88% of the unmet need for antiretro-virals.

Since ART programmes are quite new and still being rolled out, many countries do not yet have standardized national patient-monitoring systems that require regular reporting of numbers of new patients on treatment, adherence rates, number of defaulters, loss to follow up and deaths. In many countries, the Ministry of Health currently obtains information about the number of people on treatment by directly contacting the sites providing treatment.

The level of detail in the data varies between countries. WHO seeks information on numbers of people who are currently on treatment--i.e., the number of people who continue to collect their drugs in line with the recommended schedule. However, some clinics and countries report cumulative data on the number of people starting treatment. The difference between the two numbers will reflect losses due to discontinuation of treatment or death. In addition, the double counting of people who change clinics and are reported as new patients will result in over-reporting. WHO also requests disaggregated data on the number of people on ART by age and sex: i.e., number of children, adult men and adult women. …

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