TB disease yield from household contact screening of TB index patients in Pakistan

OBJECTIVES: The national guidelines recommend contact screening of a subset of patients with the TB index and their household contacts (HHCs). Thus, many contacts with TB remain unscreened. METHODS: We collected prospective data under programmatic conditions in Karachi, Pakistan, from January 2018 to December 2019. We screened all HHCs of all patients using the TB index. We disaggregated the data into guideline-eligible or ineligible index patients and contacts. We calculated TB disease yields for different groups of index patients and contacts. RESULTS: Of 39,168 HHCs from 6,450 index patients, 21,035 completed clinical assessments for TB, and 416 were diagnosed with all forms of TB. HHCs of patients with clinically diagnosed pulmonary TB (PTB) were as likely to be diagnosed with TB as the HHCs of patients with bacteriologically confirmed PTB (adjusted OR 1.28, 95% CI 0.94-1.75). The yield of TB disease among child contacts (3.4%) was significantly higher than that among adult contacts (0.5%) (P < 0.001). CONCLUSIONS: Broadening household contact screening criteria could increase the yield of contact tracing and improve the diagnosis of TB. However, further studies are required to establish the feasibility and cost-effectiveness of this approach, including studies from more diverse settings.