Atopic dermatitis and psoriasis do not share a vascular signature

Design

cross-sectional proteomic study with carotid and femoral ultrasound for plaque

Population

34 patients with moderate-to-severe atopic dermatitis, 34 with psoriasis, 20 healthy controls

Primary outcome

circulating proteomic profile and its association with subclinical atherosclerotic plaque

Effect

atopic dermatitis-specific signature with enriched atherosclerosis pathways; composite proteomic score discriminated plaque with AUC 0.94, outperforming traditional risk factors

The cardiovascular risk attached to psoriasis is well established. Whether atopic dermatitis carries a comparable one, and by what route, is not. A cross-sectional study profiled serum from 34 patients with moderate-to-severe atopic dermatitis against 34 with psoriasis and 20 healthy controls, using inflammatory and cardiovascular proteomic panels, and scanned every participant's carotid and femoral arteries for plaque.

Atopic dermatitis showed raised T-helper-2 markers as expected (CCL13, ST2, interleukin-13) but also innate and T-helper-1 and 17 markers (interleukin-6, interleukin-18, interferon-γ, interleukin-17 receptor A), alongside cardiovascular proteins including CCL19, FGF21, HGF and P-selectin, with atherosclerosis pathways enriched. Within the atopic dermatitis group, participants with plaque had higher low-density lipoprotein receptor, CDH5, transferrin receptor, CCL19 and CCL25, and lower IGFBP-2, and these tracked with plaque burden. A composite proteomic score discriminated plaque with an area under the curve of 0.94, outperforming conventional risk factors. The plaque-associated proteins differed markedly from those in psoriasis.

This is mechanism, not a clinical tool. Thirty-four patients is small for a biomarker score, an area under the curve of 0.94 derived in the same sample it was built from is almost certainly optimistic, and nothing here has been validated externally. The usable message is a directional one: the vascular association in atopic dermatitis appears to run through a different biology from psoriasis, so importing psoriasis cardiovascular screening practice wholesale is not obviously right.

• Do not order proteomic panels — this score has not been validated outside the sample that produced it.
• Do assess conventional cardiovascular risk in moderate-to-severe atopic dermatitis; that recommendation stands on other evidence.
• Record blood pressure, lipids, glycaemia and smoking at the point you start systemic therapy.
• Do not assume psoriasis cardiovascular guidance transfers — the plaque-associated proteins were different.
• Treat an area under the curve derived in a 34-patient sample as a hypothesis, not a performance figure.

Why it matters

If the vascular biology of atopic dermatitis differs from psoriasis, the screening approach borrowed from psoriasis may be aimed at the wrong thing.

Don't overread it

Cross-sectional and small — this cannot show that the proteins cause the plaque, or that treating the skin changes the vasculature.

The statistics, in plain English

An area under the curve of 0.94 would be excellent discrimination if it had been measured in a separate group of patients. Derived and tested in the same 34 people, it is an upper bound rather than an estimate, and scores built this way routinely lose a great deal of performance on external validation. The group comparisons rest on 34 versus 34 versus 20 participants, which is enough to detect large protein differences and not enough to characterise who is at risk.

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