Magadi, M., & Desta, M. (2011). A multilevel analysis of the determinants and cross-national variations of HIV seropositivity in sub-Saharan Africa: Evidence from the DHS. Health & Place, 17(5), 1067–1083.
Unit of clustering: Clustering was conducted at three levels: individual (first), regional (second), and country (third).
Hypothesized effects: This was an exploratory study designed to: (a) determine the individual and contextual socio-economic and demographic risk factors of HIV seropositivity among males and females in sub-Saharan Africa; (b) explore potential pathways of the determinants of HIV seropositivity with respect to proximate factors related to awareness, stigma, and sexual behavior; (c) explore contextual regional and country factors associated with HIV seropositivity; and (d) examine national and sub-national variations in the risk of HIV seropositivity. It emphasized the differences between males and females as well as cross-national differences.
This was a secondary analysis of existing data from the international DHIS programme and AIDS indicator surveys collected between 2003 and 2008. In includes data from 20 countries, 199 regions, and 174,592 individuals (95,759 women and 78,833 men).
Level at which exposure is measured: Exposures were measured at all three levels: individual, regional and country.
Statistical model used to estimate the effect: Four different multilevel logistic regression models were used to explore the individual and contextual regional and country level factors associated with the risk of HIV seropositivity. Model 0 has only the random region and country effects (no covariates) and subsequent models add a few country and regional level factors and several individual factors. Model 1 adds media exposure at the country, regional and individual level, as well as, socio-economic and demographic individual factors. Model 2 adds HIV stigma factors at the regional and individual levels, proportion tested for HIV at the regional level, and HIV awareness at the individual level. Model 3 adds marital information and sexual behavior factors at the individual level.
Describe whether other models might be appropriate and whether they would be preferable: Given the small number of country-level units (20), it may have been more appropriate to conduct this as a two-level analysis. Also, I’m concerned that the exposures measured at an individual level are not independent of one another, in particular those concerning awareness, stigma, and media exposure. Furthermore, it’s not clear to why these were included at multiple levels.