Barriers to adherence with tuberculosis contact investigation in six provinces of Vietnam: a nested case-control study

Background: Close contacts of patients with tuberculosis ( TB) have a substantial risk of developing the disease, particularly during the first year after exposure. Household contact investigation has recently been recommended as a strategy to enhance case detection in high- burden countries. However the barriers to its implementation in these settings remain poorly understood. Methods: A nested case- control study was conducted in Vietnam within the context of a large cluster randomised controlled trial of active screening for TB in household contacts of patients with pulmonary TB. The study population comprised contacts ( and their index patients) from 12 Districts in six provinces throughout the country. Cases were contacts ( and their index patients) that did not attend the scheduled screening appointment. Controls were those who did attend. We assessed relevant knowledge, attitudes and practices in cases and controls. Results: The acceptability of contact investigation was high among both cases ( n = 109) and controls ( n = 194). Both cases ( 47%) and controls ( 36%) commonly reported discrimination against people with TB. Cases were less likely than controls to understand that sharing sleeping quarters with a TB patient increased their risk of disease ( OR 0.46, 0.27 - 0.78) or recognise TB as an infectious disease ( OR 0.65, 0.39 - 1.08). A higher proportion of cases than controls held the mistaken traditional belief that a non- infectious form of TB caused the disease ( OR 1.69, 1.02 - 2.78). Conclusions: The knowledge, attitudes and practices of contacts and TB patients influence their ongoing participation in contact investigation. TB case detection policies in high- prevalence settings can be strengthened by systematically evaluating and addressing locally important barriers to attendance.