The recent systematic review of interventions for active case-finding for tuberculosis1Burke RM Nliwasa M Feasey HRA et al.Community-based active case-finding interventions for tuberculosis: a systematic review. and the accompanying Comment2Ortiz-Brizuela E Menzies D Tuberculosis active case-finding: looking for cases in all the right places?. published in The Lancet Public Health (May, 2021) both highlight the importance of tuberculosis infection in children as an endpoint for assessing the impact of active case-finding on disease transmission. Both state that our cluster-randomised controlled trial of community-wide active case-finding (ACT3)3Marks GB Nguyen NV Nguyen PTB et al.Community-wide screening for tuberculosis in a high-prevalence setting. showed no effect on the prevalence of tuberculosis infection in children. This is not entirely accurate.

A priori, we planned to measure the prevalence of tuberculosis infection in children born in 2012, the year before the active case-finding intervention commenced, as a co-primary endpoint. This investigation did not reveal any significant difference between the groups in the prevalence of tuberculosis infection. However, the prevalence of tuberculosis infection (2·6% in the control group) was lower than anticipated. Therefore, we did, during 2018, a further post-hoc survey of older children, born between 2004 and 2011.

The post-hoc survey revealed a substantial beneficial effect of the intervention on the prevalence of tuberculosis infection (8·3% in the control group vs 4·1% in the intervention group, prevalence ratio 0·50 [95% CI 0·32–0·78]; appendix). We acknowledge that, as a post-hoc finding, this needs to be replicated in further cluster-randomised controlled trials. Nevertheless, it remains the only evidence from a randomised comparison of active case-finding versus the usual care. Furthermore, the method and analysis were prespecified. It might be some time before further high-quality evidence is available; in the meantime, these data tend to refute the hypothesis that mass active case-finding detects “people with relatively stable disease who survive for many years; if they are less contagious, active case-finding will have little effect on transmission”.2Ortiz-Brizuela E Menzies D Tuberculosis active case-finding: looking for cases in all the right places?. Further long-term studies of active case-finding are required.

We declare no competing interests.

Supplementary MaterialReferences1.Burke RM Nliwasa M Feasey HRA et al.

Community-based active case-finding interventions for tuberculosis: a systematic review.

Lancet Public Health. 6: e283-e2992.Ortiz-Brizuela E Menzies D

Tuberculosis active case-finding: looking for cases in all the right places?.

Lancet Public Health. 6: e261-e2623.Marks GB Nguyen NV Nguyen PTB et al.

Community-wide screening for tuberculosis in a high-prevalence setting.

N Engl J Med. 381: 1347-1357Article InfoPublication HistoryIdentification

DOI: https://doi.org/10.1016/S2468-2667(21)00130-4

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Community-based active case-finding for tuberculosis might be effective in changing tuberculosis epidemiology and thereby improving population health if delivered with high coverage and intensity. If possible, active case-finding projects should incorporate a well designed, robust evaluation to contribute to the evidence base and help elucidate which delivery methods and diagnostic strategies are most effective.

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