The incidence of subclinical tuberculosis among people with HIV in a South African study was similar to the incidence of clinical TB, suggesting that guidelines recommending symptom-based screening may need to be updated, researchers said.

“Globally, TB mortality remains unacceptably high with 1.4 million deaths each year. WHO’s ambitious End TB strategy focuses on early TB diagnosis and treatment of symptomatic individuals to achieve a 90% reduction in TB incidence by 2035,” Kogieleum Naidoo, MBChB, PhD, clinical head of the HIV and TB treatment research program at the Centre for the AIDS Programme of Research in South Africa (CAPRISA), and colleagues wrote.

They said undiagnosed asymptomatic subclinical TB “remains a significant threat to global TB control and accounts for a substantial proportion of cases among people living with HIV/AIDS.”

Naidoo and colleagues enrolled 402 adults with HIV who were previously treated for TB in the CAPRISA TRuTH study and screened them for TB over 36 months while they received HIV services, including ART. They used the data to estimate the incidence rates of TB.

Of the 402 adults, 48 (11.9%) had bacteriologically confirmed incident recurrent TB, including 17 (35.4%) with subclinical TB and 31 (64.5%) with clinical TB. The study showed that age, sex and BMI were similar among participants with subclinical, clinical and no TB.

According to Naidoo and colleagues, the incidence rates of recurrent TB overall, clinical TB and subclinical TB were 2.3 (95% CI, 1.7-3), 1.5 (95% CI, 1.1-2.2) and 0.9 (95% CI, 0.5-1.4) per 100 person-years, respectively.

In the subclinical TB group, 14 (82.4%) of the patients were diagnosed by TB culture only, 11 (64.7%) received TB treatment and six (35.3%) resolved TB spontaneously.

“Our study highlights the cyclical nature of TB disease progression and need for reconsideration of current TB screening and testing guidelines,” the authors wrote. “The challenge of using TB symptoms alone for finding and treating TB cases is demonstrated, emphasizing the importance of targeted universal TB screening, and testing among high-risk groups.”