Cost-effectiveness of household contact investigation for detection of tuberculosis in Pakistan

Objectives: Despite WHO guidelines recommending household contact investigation, and studies showing the impact of active screening, most tuberculosis (TB) programmes in resource-limited settings only carry out passive contact investigation. The cost of such strategies is often cited as barriers to their implementation. However, little data are available for the additional costs required to implement this strategy. We aimed to estimate the cost and cost-effectiveness of active contact investigation as compared with passive contact investigation in urban Pakistan.

Methods: We estimated the cost-effectiveness of 'enhanced' (passive with follow-up) and 'active' (household visit) contact investigations compared with standard 'passive' contact investigation from providers and the programme's perspective using a simple decision tree. Costs were collected in Pakistan from a TB clinic performing passive contact investigation and from studies of active contact tracing interventions conducted. The effectiveness was based on the number of patients with TB identified among household contacts screened.

Results: The addition of enhanced contact investigation to the existing passive mode detected 3.8 times more cases of TB per index patient compared with passive contact investigation alone. The incremental cost was US$30 per index patient, which yielded an incremental cost of US$120 per incremental patient identified with TB. The active contact investigation was 1.5 times more effective than enhanced contact investigation with an incremental cost of US$238 per incremental patient with TB identified.

Conclusion: Our results show that enhanced and active approaches to contact investigation effectively identify additional patients with TB among household contacts at a relatively modest cost. These strategies can be added to the passive contact investigation in a high burden setting to find the people with TB who are missed and meet the End TB strategy goals.