Understanding the decline of incident, active tuberculosis in people with HIV in Switzerland. Clinical Infectious Disease
Zeeb et al. conducted a comprehensive study to evaluate trends of incident tuberculosis (TB) and its association with HIV viral suppression among people with HIV (PWH) in the Swiss HIV Cohort Study (SHCS). In addition, the study assessed the performance of screening and treating latent tuberculosis infection (LTBI) for TB prevention.
Tuberculosis was defined as detection of Mycobacterium tuberculosis in a clinical specimen associated with signs and symptoms with the disease. Incident TB cases were defined as TB diagnosis after 6 months of HIV diagnosis or SHCS registration, and LTBI was defined as a positive interferon-gamma release assay or tuberculin skin test.
Among participants in the SHCS, the TB incidence reached its peak in 1989, with 90.8 cases per 1000 person-years, and declined to 0.1 cases per 1000 person-years in 2021. This reduction was largely attributed to higher CD4 cell counts (relative indirect effect -77%) and HIV viral suppression (relative indirect effect -49%). Concurrently, LTBI prevalence dropped from a peak of 15.1% in 2001 to 4.6% in 2021. Of 1233 PWH who were tested positive for LTBI, 44% received preventive treatment. After 16 years of follow-up, 9 individuals who received preventive therapy developed TB, compared to 20 non-treated individuals. This represents an absolute risk reduction of 0.9%(95% CI 1.2% to 2.9%), or a number needed to prevent one TB case of 118. Among 277 PWH who developed incident TB, 60.1% were not tested for LTBI. Among those tested for LTBI, 73.4% had a negative test result before being diagnosed with active TB.
In conclusion, the study highlights that effective HIV treatment played a crucial role in the decline of TB cases among PWH in Switzerland. However, the low percentage (less than 50%) of individuals with positive LTBI tests receiving preventive therapy underscores the need to enhance both patient and physician acceptance of preventive TB treatment. Finally, the fact that over 70% of individuals with TB had previously tested negative for LTBI emphasizes the need for better tools to assess the TB risk of PWH.