Tuberculosis Raises Mortality Risk in HIV Infected, Even After Successful TB Treatment

A study supported by the National Institute of Allergy and Infectious Diseases (NIAID) has found that people in Latin America with HIV who were diagnosed with tuberculosis (TB) at an initial clinic visit were twice as likely to die within 10 years than those with HIV who did not have tuberculosis.

The new findings shed light on the serious global health threat of HIV and TB coinfection. According to the World Health Organization (WHO), in 2017 an estimated 920,000 people living with HIV worldwide developed TB—the leading cause of death among people with HIV—and about 300,000 people died from HIV-associated TB. In an poster presented at the Annual Conference on Retroviruses and Opportunistic Infections (CROI 2019) in Seattle, investigators say that that the risk of mortality in those who have been coinfected with HIV and TB increases even after successful TB clearance.

In an interview with Contagion^®, NIAID director Anthony S. Fauci, MD, explained that the findings raise questions about the long-term impact of TB infection in those with HIV. “If you take people who are HIV-infected, some of who have either TB or acquire TB, and others who are HIV-infected but don’t have TB, even after you finish successfully treating the TB this study showed that when you follow people for a long time the people who have had TB have a worse mortality than those who didn’t, even though both groups were HIV infected,” explained Dr. Fauci. “The issue is we don’t know what the precise mechanistic reason for that is. Is there some confounding variable among people who have had TB that gives them less of a favorable mortality?”

Dr. Fauci offers that perhaps the added inflammation occurring from TB infection creates a long-term negative affect, but the bottom line is that investigators don’t have an answer just yet. The study included nearly 16,000 HIV-positive individuals ages 18 and older in Brazil, Chile, Haiti, Honduras, Mexico, or Peru from 2006 to 2015. Study participants received care Caribbean, Central and South America Network for HIV Epidemiology (CCASAnet) clinics and had not initiated antiretroviral drug treatment prior to their first clinic visit.

Of the 1,051 individuals who were diagnosed with TB during their first visit—and who were prescribed anti-TB and HIV medications—about 10% had died after 5 years, compared with fewer than 6% of patients without TB. After 10 years, more than 19% of participants who had been coinfected with TB and HIV at their initial clinic visit had died, compared to a rate of 10.5% among those who had not had TB at the start of observation.

Dr. Fauci points out that the study included only patients with treated and treatable forms of TB, and excluded cases of multidrug-resistant (MDR TB) and extensively drug-resistant (XDR TB) infections. “The question they were asking really was once you successfully treat it, is there still a long-range negative effect, so including resistant TB would’ve completely confused that question,” explained Dr. Fauci. While the TB epidemic is not having a direct impact on achieving the 90-90-90 targets set by the United Nation’s Program on HIV/AIDS (UNAIDS), the intersection of the 2 epidemics compounds the difficulties of tackling the HIV epidemic. “Not to be simplistic but TB is a really bad disease when you have HIV. We’ve got to do better diagnosing people and treating them early.”

While a TB vaccine is currently only available for children living in regions where TB is common, Dr. Fauci points to recent advances in the development of new TB vaccines capable of offering protection for adults. “We’re doing much better on the road to a TB vaccine right now than we were 3 or 4 years ago.”

The poster, “Mortality After Presumed TB Treatment Completion in Persons With HIV in Latin America,” was presented on Wednesday, March 6, 2019, at CROI 2019 in Seattle, Washington.