Prior TB triples risk of later active TB in HIV+ people of Tanzania
Having tuberculosis in the past approximately tripled the risk of later active TB in a large study of HIV-positive Tanzanians with or without prior TB.
TB is a common complication of HIV infection—and often the leading cause of death with HIV—in regions with high rates of both TB and HIV. But the risk of recurrent TB remains incompletely understood.
This study involved 979 HIV-positive adults with a CD4 count at or above 200 cells/μL. Everyone had received the BCG vaccine and had received placebo in the DarDar TB vaccine trial in Tanzania. Everyone with a positive tuberculin skin test without prior active TB was offered isoniazid preventive therapy. The researchers used rigorous published criteria to define definite or probable TB.
During a median follow-up of 3.2 years, the researchers diagnosed 52 cases of definite TB and 92 cases of definite/probable TB in 979 study participants.
Among 80 people with prior active TB, 11 (13.8%) later had definite tuberculosis and 17 (21.3%) had definite/probable tuberculosis. Among 899 people without prior active TB, 41 (4.6%) later had definite TB and 75 (8.3%) later had definite/probable TB.
Compared with people without prior TB, those with prior TB had a tripled risk of subsequent definite TB (risk ratio [RR] 3.01, 95% confidence interval [CI] 1.61 to 5.63, P < 0.001) and a 2.55 time higher risk of subsequent definite/probable TB (RR 2.55, 95% CI 1.59 to 4.09, P < 0.001).
Statistical analysis that accounted for age, CD4 count, and isoniazid use determined that people with prior active TB had more than a tripled risk of subsequent probable TB (hazard ratio [HR] 3.69, 95% CI 1.79 to 7.63, P < 0.001) and almost a tripled risk of definite/probable TB (HR 2.78, 95% CI 1.58 to 4.87, P < 0.001).
Source: Timothy Lahey, Todd MacKenzie, Robert D. Arbeit, Muhammad Bakari, Lillian Mtei, Mecky Matee, Isaac Maro, C. Robert Horsburgh, Kisali Pallangyo, C. Fordham von Reyn. Recurrent tuberculosis risk among HIV-infected adults in Tanzania with prior active tuberculosis. Clinical Infectious Diseases. 2012; 56: 151-158.
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Source: IAS
