- Design
- systematic review and meta-analysis of 31 studies, random-effects pooling of single-arm incidence
- Population
- 15,005 patients receiving systemic therapy for immune-mediated dermatological disease
- Primary outcome
- latent tuberculosis conversion after a negative baseline test, and active tuberculosis during follow-up
- Effect
- latent conversion 4.3%, highest with TNF inhibitors; active tuberculosis 1.0%, more frequent in high-burden regions
A systematic review pooled 31 studies and 15,005 patients receiving systemic therapy for immune-mediated skin disease, reporting two outcomes that are usually conflated: conversion to latent tuberculosis infection among patients who screened negative at baseline, and active tuberculosis during follow-up.
Pooled latent infection conversion was 4.3%. It was highest with tumour necrosis factor inhibitors, followed by IL-17 inhibitors and then ustekinumab. Active tuberculosis occurred in 1.0% overall and more often in high-burden regions. Risk therefore varies along two axes at once - the mechanism of the drug and where the patient lives - and the pooled numbers from low-burden countries understate what an Indian clinic should expect.
The practical consequence is about repeat testing. A negative tuberculin skin test or interferon-gamma release assay before starting is standard; treating that result as permanent is common and, on these numbers, wrong for roughly one patient in twenty-three. Build a repeat screen into annual review for patients on TNF inhibitors in particular, and set a lower threshold for investigating cough, weight loss, fever or night sweats in anyone on any of these drugs. Where a patient is starting a TNF inhibitor in a high-burden setting, the class choice itself is part of the risk conversation: an IL-23 or IL-17 agent may carry less, and that belongs in the discussion before the first dose rather than after a conversion.
- Repeat interferon-gamma release assay or tuberculin testing at least annually on TNF inhibitors
- Record baseline screening results and the date, so a repeat is prompted rather than remembered
- Ask about cough, fever, weight loss and night sweats at every biologic review
- Factor regional TB burden into the class choice, not just the psoriasis severity score
- Involve the chest physician early for conversion - treating latent infection is not a dermatology decision alone
Why it matters
A baseline negative screen is being treated as a permanent clearance, and about one patient in twenty-three converts on treatment.
Don't overread it
These are pooled single-arm incidences without an untreated comparator; they cannot quantify how much of the risk the drug itself adds.
The statistics, in plain English
A pooled incidence of 4.3% is an average across 31 studies of differing design, follow-up length and screening intervals, so it is an order of magnitude rather than a precise rate - and because the studies were single-arm, it has no comparison against untreated patients with the same disease. The active tuberculosis figure of 1.0% is the one with clinical weight, and its concentration in high-burden regions means the local number is what matters, not the pooled one. Risk of bias was moderate to high in the included studies.
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