Latent TB conversion reaches 4.3% on systemic therapy for skin disease — highest with TNF inhibitors

Design

Systematic review and meta-analysis of trials and observational studies

Population

31 studies, 15,005 dermatology patients on systemic therapy

Primary outcome

Latent TB conversion and active TB incidence

Effect

Latent TB conversion 4.3%; active TB 1.0%, higher in high-burden regions

This meta-analysis, published 1 September in JAMA Dermatology, pooled 31 studies of 15,005 patients receiving systemic therapy — biologics with or without conventional immunosuppressants — for immune-mediated skin disease. It looked at conversion to latent TB infection among those who tested negative at baseline, and at active TB.

The pooled latent TB conversion rate was 4.3%. Conversion was highest with TNF inhibitors, followed by IL-17 inhibitors and ustekinumab. Active TB occurred in 1.0% overall, and more often in high-burden regions.

Most dermatology TB protocols were written for low-burden countries and rely on a single baseline test. In India, the background risk of exposure is much higher. These figures support choosing lower-risk classes where TB exposure is likely, repeating screening at intervals rather than only at baseline, and keeping a low threshold for investigation of new respiratory or constitutional symptoms.

• Where TB exposure risk is high, weigh that TNF inhibitors carried the highest conversion rate, followed by IL-17 inhibitors and ustekinumab.
• Repeat latent TB testing during treatment, not only at baseline, in high-burden settings.
• Investigate new cough, fever, night sweats or weight loss on a biologic promptly.
• Record the biologic class and the patient's TB exposure risk together in the treatment plan.

Why it matters

Challenges the single-baseline-test routine that most biologic protocols still follow.

Don't overread it

Class comparisons come from different studies and populations, not from randomised head-to-head data.

The statistics, in plain English

A 4.3% conversion rate means about one in 23 patients who started with a negative test became positive during follow-up. Pooled single-arm rates from mixed study designs are estimates, not comparisons from head-to-head trials.

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