What is it about?
Treating tuberculosis requires months of daily medication, so researchers often study how people behave during treatment. They usually call this “adherence.” We looked at 103 studies from 32 countries to see what researchers actually meant and measured when they used that word. We found that the same label was used for very different things: answers to a questionnaire, counting missed pills, a urine test, missed clinic visits, or a “treatment interrupted” entry in a national register. Most studies never defined what they meant by adherence and most also reduced it to a simple "adherent/not adherent" measure taken at a single moment in time.
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Why is it important?
Clinicians, health programmes and policymakers rely on adherence studies to decide what support to offer people with TB. If one study measures pill-taking and another measures clinic attendance, but both call it “adherence”, their results cannot be compared. This matters because adherence is not a fixed personal trait. People move between taking their treatment well and struggling with it as their money, work, relationships and access to care change. Treating it as a simple yes/no can hide these social and structural causes, and can unfairly label people as “non-adherent.” Our work is the first to map this mismatch in TB research and we propose three practical steps: (1) say clearly which part of treatment-taking is being studied, (2) keep the complexity of the data in the analysis, and (3) have WHO and national TB programmes set clear reporting standards.
Perspectives
This article came from a moment of frustration. While gathering evidence on what drives adherence to TB treatment, I realised they weren’t measuring the same thing. As a psychologist working in public health, I was interested in the different constructions and measurements of adherence, and the answer kept changing from one paper to the next. Turning that problem into a study of its own, with a dedicated team of co-authors, was one of the most rewarding parts of my PhD. It also shaped how I now think about adherence: less as an individual behaviour, and more as something embedded in people’s lives and circumstances. I hope this article encourages researchers and TB programmes to slow down and define what they’re measuring before counting it.
João Pedro Nunes Ramos
Universidade do Porto
Read the Original
This page is a summary of: Measurement of Tuberculosis treatment adherence: A methodological scoping review of observational studies, PLOS Global Public Health, October 2026, PLOS,
DOI: 10.1371/journal.pgph.0007422.
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