Does antiretroviral therapy reduce HIV-associated tuberculosis incidence to background rates? A national observational cohort study from England, Wales, and Northern Ireland

Abstract

Background: Whether the incidence of tuberculosis in HIV-positive people receiving long-term antiretroviral therapy (ART) remains above background population rates is unclear. We compared tuberculosis incidence in people receiving ART with background rates in England, Wales, and Northern Ireland.

Methods: We analysed a national cohort of HIV-positive individuals linked to the national tuberculosis register. Tuberculosis incidence in the HIV-positive cohort (2007-11) was stratified by ethnic origin and time on ART and compared with background rates (2009). Ethnic groups were defined as follows: the black African group included all individuals of black African origin, including those born in the UK and overseas; the white ethnic group included all white individuals born in the UK and overseas; the south Asian group included those of Indian, Pakistani, and Bangladeshi origin, born in the UK and overseas; and the other ethnic group included all other ethnic origins, including black Afro-Caribbeans.

Findings: The HIV-positive cohort comprised 79 919 individuals, in whom there were 1550 incident cases in 231 664 person-years of observation (incidence 6·7 cases per 1000 person-years). Incidence of tuberculosis in the HIV-positive cohort was 13·6 per 1000 person-years in black Africans and 1·7 per 1000 person-years in white individuals. Incidence of tuberculosis during long-term ART (≥5 years) in black Africans with HIV was 2·4 per 1000 person-years, similar to background rates of 1·9 per 1000 person-years in this group (rate ratio 1·2, 95% CI 0·96-1·6; p=0·083); but in white individuals with HIV on long-term ART the incidence of 0·5 per 1000 person-years was higher than the background rate of 0·04 per 1000 person-years (rate ratio 14·5, 9·4-21·3; p<0·0001). The increased incidence relative to background in white HIV-positive individuals persisted when analysis was restricted to person-time accrued on ART with CD4 counts of at least 500 cells per μL and when white HIV-positive individuals born abroad were excluded.

Interpretation: Tuberculosis incidence is unacceptably high irrespective of HIV status in black Africans. In white individuals with HIV, tuberculosis incidence is significantly higher than background rates in white people despite long-term ART. Expanded testing and treatment for latent tuberculosis infection to all HIV-infected adults, irrespective of ART status and CD4 cell count, might be warranted.

Funding: Public Health England.