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Risk factors for active tuberculosis in adults on highly active antiretroviral therapy in Africa

Seyler, Catherinea,b; Toure, Siakaa,b; Messou, Eugènea,b; Anglaret, Xaviera,b

doi: 10.1097/01.aids.0000233585.87338.79

aProgramme PAC-CI, Abidjan, Côte d'Ivoire, France

bINSERM U.593, Université Victor Segalen Bordeaux 2, Bordeaux, France.

Received 31 December, 2005

Accepted 24 February, 2006

Correspondence to Dr Catherine Seyler, INSERM U593, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France. E-mail:

In a recent limited article, we reported that a past history of tuberculosis (TB) at HAART initiation was significantly associated with the risk of active TB in adults on HAART in Côte d’Ivoire [1]. In another recent excellent study, Lawn and colleagues did not find such an association in South African adults [2]. This striking difference deserves further discussion.

In our study, 25% of patients had a past history of TB at HAART initiation, and 50% of the previous TB episodes were diagnosed more than 3 years prior to enrolment [1]. In the study by Lawn and colleagues, only 14% of patients had a TB history at baseline, and 50% of the previous TB episodes were diagnosed within the 13 months prior to enrolment [2]. Thus, we wonder if some previous episodes of TB could have been missed, particularly among the remotest ones. In sub-Saharan Africa, under-report of previous episodes is a well-known cause of TB recurrence underestimation [3]. As TB recurrence may vary over time [4], under-documenting the oldest past-episodes compared with the most recent ones could introduce a major bias in the analyses looking at the association between TB history and TB occurrence during HAART.

There is another consequence of this unusual distribution of the time since last episode in the study by Lawn and colleagues. Most of their patients with TB history received anti-TB drugs within the few months preceding HAART initiation. Thus, their trend toward an association between the variable ‘TB history’ and a lower risk of active TB during HAART is hard to distinguish from a trend toward a time-limited reduction in TB risk due to recent anti-TB treatment. This trend could even be interpreted as a strong argument for the necessity to assess the benefits of a time-limited TB prophylactic treatment during the first months of HAART.

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1. Seyler C, Toure S, Messou E, Bonard D, Gabillard D, Anglaret X. Risk factors for active tuberculosis after antiretroviral treatment initiation in Abidjan. Am J Respir Crit Care Med 2005; 172:123–127.
2. Lawn SD, Badri M, Wood R. Tuberculosis among HIV-infected patients receiving HAART: long term incidence and risk factors in a South African cohort. AIDS 2005; 19:2109–2116.
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© 2006 Lippincott Williams & Wilkins, Inc.