Risk factors for mortality in smear-negative tuberculosis suspects: a cohort study in Harare, Zimbabwe

Area of Science:

• Infectious Diseases
• Public Health
• Clinical Medicine

Background:

• Tuberculosis (TB) remains a significant global health challenge, particularly in co-infection with Human Immunodeficiency Virus (HIV).
• Smear-negative TB suspects represent a diagnostic challenge and may be overlooked, potentially leading to delayed treatment and adverse outcomes.
• Understanding mortality patterns and risk factors in this population is critical for effective public health interventions.

Purpose of the Study:

• To investigate the mortality rates among individuals suspected of having smear-negative tuberculosis.
• To identify key risk factors associated with death in this vulnerable patient group.
• To evaluate the impact of HIV co-infection and its management on mortality.

Main Methods:

• A cohort study was conducted, nested within a cluster-randomised trial focused on community-based active case finding.
• Smear-negative TB suspects were followed for 12 months, with home tracing employed to ensure comprehensive data collection.
• Regression analysis was utilized to examine the relationship between clinical characteristics and mortality.

Main Results:

• The study followed 1195 smear-negative TB suspects, with a Human Immunodeficiency Virus (HIV) prevalence of 63.3%.
• A significant mortality rate of 11.6% was observed, with HIV-positive individuals experiencing a 5.8-fold higher risk of death compared to HIV-negative individuals.
• Advanced immunosuppression (CD4 count < 50 cells/µL) was a major risk factor for death in HIV-positive participants, and only 14.7% initiated Antiretroviral Treatment (ART) with considerable delays.

Conclusions:

• HIV-positive smear-negative TB suspects face a high and persistent risk of mortality.
• Current management guidelines for HIV-infected TB suspects are insufficient, highlighting the need for improved strategies.
• The findings underscore the necessity for policies promoting earlier HIV and TB diagnosis and expedited ART initiation to reduce mortality.