Counting hard-to-count populations: the network scale-up method for public health

Estimating sizes of hidden or hard-to-reach populations is an important problem in public health. For example, estimates of the sizes of populations at highest risk for HIV and AIDS are needed for designing, evaluating and allocating funding for treatment and prevention programmes. A promising approach to size estimation, relatively new to public health, is the network scale-up method (NSUM), involving two steps: estimating the personal network size of the members of a random sample of a total population and, with this information, estimating the number of members of a hidden subpopulation of the total population. We describe the method, including two approaches to estimating personal network sizes (summation and known population). We discuss the strengths and weaknesses of each approach and provide examples of international applications of the NSUM in public health. We conclude with recommendations for future research and evaluation

Ending AIDS as a public health threat by 2030: Time to reset targets for 2025.

Paul De Lay and co-authors introduce a Collection on the design of targets for ending the AIDS epidemic

Life expectancy after initiation of combination antiretroviral therapy in Thailand

Background: Access to combination antiretroviral therapy (cART) has decreased mortality in HIV-positive people. We aimed to estimate the expected additional years of life in HIV-positive Thai people after starting cART through the National AIDS Program (NAP), administered by the Thai National Health Security Office (NHSO). Methods: The NHSO database collects characteristics of all Thai HIV-infected patients through the National AIDS Program, including linkage with the National Death Registry for vital status. This study included patients aged >= 15 years at cART initiation between 2008 and 2014. The abridged life table method was used to construct life tables stratified by sex and baseline CD4(+) T-cell count. Life expectancy was defined as the additional years of life from age at starting cART. Results: 201,688 eligible patients were included in analyses, contributing 618,837 person-years of followup. Median CD4(+) T-cell count was 109 cells/mm(3) and median age 37 years. The overall life expectancy after cART initiation at age 20 was 25.4 (95% CI, 25.3, 25.6) years and 20.6 (95% CI, 20.5, 20.7) at age 35 years. Life expectancy at baseline CD4(+) T-cell count >= 350 cells/mm(3) was 51.9 (95% CI, 51.0, 52.9) years for age 20 years and 43.2 (95% CI, 42.4, 44.1) years for age 35 years, close to life expectancy in the general Thai population. Conclusions: Increasing life expectancy with higher baseline CD4(+) T-cell counts supports the guideline recommendations to start cART irrespective of CD4(+) T-cell count. These results are beneficial to forecast the treatment cost and develop health policies for people living with HIV in Thailand and Asi

HIV service delivery models towards ‘Zero AIDS-related Deaths’: a collaborative case study of 6 Asia and Pacific countries

BackgroundIn the Asia-Pacific region, limited systematic assessment has been conducted on HIV service delivery models. Applying an analytical framework of the continuum of prevention and care, this study aimed to assess HIV service deliveries in six Asia and Pacific countries from the perspective of service availability, linking approaches and performance monitoring for maximizing HIV case detection and retention.MethodsEach country formed a review team that provided published and unpublished information from the national HIV program. Four types of continuum were examined: (i) service linkages between key population outreach and HIV diagnosis (vertical-community continuum); (ii) chronic care provision across HIV diagnosis and treatment (chronological continuum); (iii) linkages between HIV and other health services (horizontal continuum); and (iv) comprehensive care sites coordinating care provision (hub and heart of continuum).ResultsRegarding the vertical-community continuum, all districts had voluntary counselling and testing (VCT) in all countries except for Myanmar and Vietnam. In these two countries, limited VCT availability was a constraint for referring key populations reached. All countries monitored HIV testing coverage among key populations.Concerning the chronological continuum, the proportion of districts/townships having antiretroviral treatment (ART) was less than 70% except in Thailand, posing a barrier for accessing pre-ART/ART care. Mechanisms for providing chronic care and monitoring retention were less developed for VCT/pre-ART process compared to ART process in all countries.On the horizontal continuum, the availability of HIV testing for tuberculosis patients and pregnant women was limited and there were sub-optimal linkages between tuberculosis, antenatal care and HIV services except for Cambodia and Thailand. These two countries indicated higher HIV testing coverage than other countries.Regarding hub and heart of continuum, all countries had comprehensive care sites with different degrees of community involvement.ConclusionsThe analytical framework was useful to identify similarities and considerable variations in service availability and linking approaches across the countries. The study findings would help each country critically adapt and adopt global recommendations on HIV service decentralization, linkages and integration. Especially, the findings would inform cross-fertilization among the countries and national HIV program reviews to determine county-specific measures for maximizing HIV case detection and retention