Slightly more than 60% of tuberculosis disease cases in southern Africa occur in people with HIV infection, according to a regional analysis of TB numbers. Across the world, people with HIV account for 21% of all TB deaths.
Informed tuberculosis planning depends on the best possible estimates of TB incidence (the new-diagnosis rate) and prevalence. TB estimates appear yearly in the World Health Organization (WHO) Global Tuberculosis Reports (linked below). Researchers from the Futures Institute, WHO, and other institutions developed new methods to determine whether overall results were similar to prior WHO estimates and to make country-by-country estimates of TB in people with HIV.
The investigators devised a regression model to relate CD4-count changes to risk of TB disease. Into this model they incorporated all available country-level data on TB incidence in people with HIV. For countries with no TB-HIV incidence data, they applied global regression parameters determined by averaging results over countries that did have HIV-TB incidence data.
These methods yielded estimates reasonably close to those of existing estimates of global TB-HIV burden. The model figured the people with HIV and TB account for 12.6% of worldwide TB incidence, 21.3% of all TB deaths, and 20% of all HIV deaths.
Regional estimates indicated the highest absolute TB incidence in East and Southeast Asia but the highest per capita incidence in sub-Saharan Africa. In Central sub-Saharan Africa, an estimated 12.5% of all TB disease cases occur in people with HIV. In Southern sub-Saharan Africa, an estimated 60.6% of all TB disease cases occur in people with HIV.
Regional analysis also showed that a disproportionate percentage of global TB deaths (12.1%) relative to global TB incidence (8.7%) occur in Southern sub-Saharan Africa.
This analysis yielded TB-HIV incidence and mortality results published in WHO’s Global Tuberculosis Report 2013 and Global Tuberculosis Report 2014 (linked below). The authors note that the simple method they developed generates “internally consistent estimates for tuberculosis/HIV incidence and mortality, which have had immediate tuberculosis programme planning uses.”
Source: Carel Pretorius, Philippe Glaziou, Peter J. Dodd, Richard White, Rein Houben. Using the TIME model in Spectrum to estimate tuberculosis-HIV incidence and mortality. AIDS. 2014; 28 (Suppl 4): S477-S487.