London School of Hygiene & Tropical Medicine

Interventions using active finding of tuberculosis (TB) cases can reduce the prevalence of the disease, according to a new study published in the Lancet Public Health.

The systematic review and analysis, which was carried out by a team of international researchers including from the London School of Hygiene & Tropical Medicine (LSHTM), has contributed to the World Health Organization’s (WHO’s) new tuberculosis screening guidelines.

TB remains one of the world’s leading infectious killers, with an estimated 1.4 million people dying from tuberculosis in 2020.

Many people with TB experience long delays before diagnosis, during which they are at risk of severe illness and death, and can pass infection to others. Active case finding interventions, aim to identify people with the disease earlier in the community through screening, health promotion and linkage to effective treatment. Until now, there has not been high quality evidence for how effective they are.

The study assessed the impact of active case finding interventions on TB epidemiology at community-level (numbers of people diagnosed with TB, numbers of people with infectious tuberculosis in the community, and rates of latent tuberculosis infection).

The researchers systematically assessed data from 36 tuberculosis active case finding studies conducted throughout the world, and included more than 110 million-person years of follow-up. They found that active case finding interventions can reduce the prevalence of tuberculosis in communities if targeted to areas where disease is common and using high-intensity screening approaches.

Dr Rachael Burke from LSHTM and Malawi Liverpool Wellcome Trust and study first author said: "Active case finding for tuberculosis is likely to increase the number of people with tuberculosis identified and treated, and, might be able to reduce prevalence of tuberculosis in communities.  However, there is still a lot we don’t know, and we recommend that where active case finding interventions are introduced, more data should be collected to address knowledge gaps about benefits and harms in different settings and in different populations."

Dr Peter MacPherson from the Liverpool School of Tropical Medicine, who led the study, said: “Tuberculosis remains one of the most important diseases globally, and disproportionately affects the poorest people. Although these programmes have been implemented in many communities and countries throughout the globe, we have until now had little evidence to say whether or not they are effective. In this study, the largest of its kind ever conducted, we synthesised all the available evidence and showed that active case finding can reduce community prevalence of tuberculosis, if delivered with sufficient intensity and coverage.”

The authors recommend that further research is still needed to investigate which communities can benefit most from active case finding interventions, and how they may be most effectively and efficiently delivered to maximise benefits for individuals and communities.

Publication:

Rachael Burke et al. Community-based active case-finding interventions for tuberculosis: a systematic review. Lancet Public Health. DOI:10.1016/ S2468-2667(21)00033-5