Consolidated guidance on tuberculosis data generation and use: Module 3 – National tuberculosis prevalence surveys

What this guideline says

GMJ summary

This 336-page WHO handbook provides comprehensive technical guidance for designing, implementing, analysing and reporting national tuberculosis (TB) prevalence surveys. It updates the widely used 2011 ‘lime book’ with major revisions to diagnostic algorithms, recommending either Xpert® MTB/RIF Ultra testing followed by liquid culture confirmation (Option 1) or liquid culture testing with rapid Xpert Ultra for clinical management (Option 2). National TB prevalence surveys are recommended for countries with estimated TB incidence ≥150 per 100 000 population per year, no high-quality vital registration system, and a UHC service coverage index score <80.

The guidance covers all aspects of survey conduct: sampling design (typically 30 000–70 000 participants aged ≥15 years), screening strategies using symptom questionnaire and chest X-ray (with digital radiography and computer-aided detection), laboratory procedures, data management systems, ethical considerations, budgeting, and quality assurance. It emphasizes that surveys measure bacteriologically confirmed pulmonary TB in adults, with systematic screening identifying 1–5% of participants as screen-positive for diagnostic testing. Between 2007 and 2023, 37 national surveys were completed in 32 countries, providing critical data for TB burden estimation and programme improvement.

The handbook includes 20 detailed chapters with standard operating procedures, case definitions, sampling calculations, field operation protocols, data analysis plans, and guidance on comparing results with previous surveys. It addresses the main challenges identified in earlier surveys: ensuring high-quality culture testing and robust data management. The guidance is intended for national TB programmes, research institutes, national statistics agencies, and international technical partners supporting survey implementation.

Key points

For clinicians — doses and thresholds as stated in the guideline

1. Surveys are recommended for countries with TB incidence ≥150/100 000/year, no high-quality vital registration, and UHC service coverage index <80.
2. Target population: adults aged ≥15 years; sample size typically 30 000–70 000 participants to achieve precise prevalence estimates.
3. Screening: symptom questionnaire (cough ≥2 weeks or any duration, haemoptysis, fever, chest pain, weight loss) plus digital chest X-ray for all consenting participants.
4. Option 1 diagnostic algorithm: two Xpert Ultra tests on all screen-positive individuals; if either positive, collect two additional specimens for liquid culture (MGIT) confirmation.
5. Option 2 diagnostic algorithm: two specimens for liquid culture (MGIT) plus one Xpert Ultra test (for rapid clinical management) from all screen-positive individuals.
6. Survey TB case definition (Option 1): ≥1 Xpert Ultra positive AND ≥1 MGIT culture positive for Mycobacterium tuberculosis; or both Xpert Ultra results positive at very low or higher with no TB treatment history in past 5 years if culture negative/missing.
7. Expected screen-positive rate: 5–25% of participants based on CXR abnormalities or symptoms; among screen-positive individuals, 1–5% expected to have bacteriologically confirmed TB.
8. Quality assurance essential: external reference laboratory validation of culture results; systematic monitoring of Xpert-culture concordance; radiation safety board approval for X-ray equipment use in community settings.

Epidemiological criteria for countries to consider implementing a national TB prevalence survey (Table 1.1)

Table extracted from the guideline

Source: World Health Organization, Consolidated guidance on tuberculosis data generation and use: Module 3 – National tuberculosis prevalence surveys. Reproduced in summary form.

What changed in this edition

Versus the previous edition

• Major revision of diagnostic algorithms: now recommends either Xpert Ultra followed by MGIT culture confirmation (Option 1) or MGIT culture with Xpert Ultra for clinical management (Option 2), replacing previous reliance on smear microscopy and solid culture.
• Xpert Ultra sensitivity ~80–90% vs liquid culture but more sensitive than solid culture; specificity ~95% means confirmatory culture required to avoid false positives in low-prevalence survey populations.
• Elimination of medical panel for case classification; strict objective case definitions now used with statistical imputation for indeterminate results.
• Updated and expanded guidance on digital chest radiography and computer-aided detection (CAD) software for screening.
• Comprehensive new chapters on: HIV and comorbidities testing; survey monitoring; data management (with digitalization); comparisons with previous surveys; reporting and dissemination; use of survey data.
• Updated sampling design and analysis methods to account for new diagnostic algorithms and case definitions.
• Revised epidemiological criteria for survey eligibility: incidence threshold ≥150/100 000 (previously varied); explicit UHC service coverage requirement.

From the guideline

Verbatim

“The best diagnostic algorithm (in terms of sensitivity) is to test two samples from all screen-positive individuals with liquid culture, but this is only the case if a high quality of liquid-culture testing can be achieved.”

Editor’s perspective

Why this matters for Georgia and the region

Applicability

Georgia and the South Caucasus

Questions this guideline answers

Quick answers

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