Annexure- Codebook used for data.

Household contact (HHC) investigation helps in early identification of people with tuberculosis (TB) and initiation of TB preventive treatment (TPT) among those at high risk of developing TB. This cross-sectional study uses National TB Elimination Program data of all people notified with bacteriologically confirmed pulmonary TB and their HHCs from October to December 2023, from Chhattisgarh, a central Indian state, to assess coverage of HHC investigation, proportions identified with TB and put on TPT (all age groups and age < 5 years). Sociodemographic, clinical, and health system-related factors were used to identify predictors of HHC investigation not done, as determined through modified Poisson regression. Of the 4,221 people notified with TB, an HHC investigation was conducted for 3,177 (75%) cases. Among a total of 11670 contacts screened, TB was diagnosed in 0.9%(n = 109) for all age groups and 0.7%(n = 9) for children<5 years. TPT was initiated in 66% (n = 7740) for all age groups and 73% (n = 903) for children<5 years. Women (adjusted prevalence risk aPR 1.10; 95%CI:1.01-1.19), those notified from non-tribal districts (aPR 1.14; 95%CI:1.01-1.29), current facility being tertiary care (aPR 1.50; 95%CI:1.12-2.00) and private (aPR 1.42; 95%CI:1.08-1.86) facility, diagnosed with test other than sputum microscopy (aPR NAAT 3.19; 95%CI:2.39-4.28; LPA 8.88 95%CI:6.15-12.82; culture 9.69; 95%CI:5.99-15.68) and for whom diabetes (aPR 1.40; 95%CI:1.16-1.70) and HIV screening (aPR 1.55, 95% CI:1.17-2.05) was missing predicted higher risk of HHC investigation not done. The study highlights the need to improve HHC investigation, as well as the low yield of TB and TPT initiation. Predictors of HHC investigation not done suggest a need to decentralize it to the primary level and improve data-based program monitoring. A statewide capacity-building initiative for improving the investigation of HHC is the way forward.