Isoniazid preventive therapy care cascade and associated determinants among under-five child contacts of pulmonary tuberculosis patients in urban tuberculosis unit of a district, India

Isoniazid Preventive Therapy (IPT), the isoniazid-based form of Tuberculosis Preventive Therapy (TPT), substantially reduces the risk of progression from latent tuberculosis infection to active disease in children under five years of age residing with infectious pulmonary tuberculosis patients. Despite robust programmatic guidelines, India’s preventive care cascade faces significant implementation challenges with persistent losses at multiple stages from identification to treatment completion. (i)To characterise the TPT care cascade among under-five household contacts of pulmonary tuberculosis index cases in urban Kalaburagi district; (ii)To identify factors associated with TPT completion; and (iii)To explore caregiver and system-level barriers and facilitators influencing TPT initiation and completion. A sequential explanatory mixed-methods study was conducted at two urban tuberculosis units (TUs) in Kalaburagi district, Karnataka, India. The quantitative component comprised a community-based cross-sectional investigation of 91 pulmonary tuberculosis index cases and their 179 under-five child contacts. The qualitative component involved in-depth interviews with ten purposively selected caregivers; thematic saturation was achieved by the eighth interview. Associations between sociodemographic variables and TPT completion were examined using chi-square or Fisher’s exact tests. Multivariable logistic regression was conducted to calculate Adjusted Odds Ratios (AOR) and 95% CIs, adjusting for family type, household size, socioeconomic status, and number of child contacts. Qualitative data were analysed thematically and integrated with quantitative findings using a joint display approach. Of the 179 eligible child contacts, 70.9% (95% CI 63.8–77.4%) underwent tuberculosis screening. Among those screened, only 49.6% (95% CI 40.7–58.5%) initiated TPT, and 49.2% (95% CI 36.5–62.0%) of initiators completed the full six-month course, yielding an overall cascade completion rate of 17.3% (95% CI 12.1–23.8%; 31/179), equivalent to only approximately 1 in 6 eligible children. On adjusted analysis, TPT completion was significantly associated with nuclear family structure (AOR 3.87; 95% CI 1.18–12.69), smaller households (AOR 5.92; 95% CI 1.78–19.68), higher socioeconomic status (AOR 9.43; 95% CI 1.82–48.95), and fewer under-five contacts (AOR 4.21; 95% CI 1.01–17.60). Qualitative analysis identified five themes: limited caregiver knowledge of tuberculosis prevention; diagnostic delay with initial private-sector reliance; trust in frontline workers as a facilitator; practical barriers and elder-mediated social pressure; and missed opportunities attributable to inadequate counselling. Only approximately 1 in 6 eligible under-five child contacts of pulmonary tuberculosis patients completed the full course of TPT, representing a critical and actionable gap in the NTEP (National Tuberculosis Elimination Programme) cascade. These findings underscore the urgent need for structured caregiver counselling at index case registration, sustained community follow-up by ASHA (Accredited Social Health Activist) and Anganwadi workers, child-friendly TPT formulations, and routine cascade monitoring embedded within NTEP reporting frameworks.