Pustular flares after stopping biologics: who is at risk

Design

Multicentre retrospective cohort of treatment episodes

Population

1,198 biologic withdrawal episodes in responders with plaque psoriasis

Primary outcome

Distinct pustular psoriasis flare after withdrawal

Effect

Flare in 86 of 1,198 episodes (7.2%)

This multicentre study examined 1,198 episodes in which patients with plaque psoriasis responded to a biologic and then stopped it, between 2011 and 2025.

A distinct pustular flare followed 86 episodes (7.2%): painful, diffuse, intense erythema with pustules and swelling, mainly on the lower limbs. Its frequency rose with each cycle of withdrawal and relapse. Independent risk factors were a family history of psoriasis, psoriatic arthritis, a previous flare of this type, more previous withdrawal-relapse cycles and a slower time to PASI 50 on biologic therapy.

Biologic holidays are common, and the default assumption is that relapse will look like the original plaque disease. This study describes a different, more aggressive relapse in about 1 in 14 withdrawals, and gives a checklist for who should not be taken off treatment casually. It is observational, without histology, so it cannot say whether this is generalised pustular psoriasis or a separate entity.

• Avoid repeated stop-start cycles of biologics in psoriasis; flare risk rose with each cycle.
• Be cautious about pausing biologics in patients with psoriatic arthritis, a family history or a previous pustular flare.
• Resume the biologic early if a painful pustular flare develops after stopping.
• Note a slow initial response (long time to PASI 50) as a marker of higher flare risk.

Why it matters

It challenges the idea that a biologic holiday is low risk because relapse will simply be plaque disease again.

Don't overread it

Observational, with no histology or molecular data; the risk factors are associations, not proof of cause.

The statistics, in plain English

The 7.2% figure is per withdrawal episode, not per patient, and the generalised estimating equation model accounts for the same patient appearing more than once. The abstract does not give effect sizes for the individual risk factors.

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