Investigating serum procalcitonin levels in rosacea: a cross-sectional case-control study.

BACKGROUND

Rosacea is a chronic inflammatory skin disorder involving dysregulated innate immunity and microbial interactions. Procalcitonin (PCT) is a serum biomarker of bacterial inflammation but its role in rosacea remains unclear.

OBJECTIVES

To assess serum PCT levels in rosacea patients compared to healthy controls and explore associations with treatment modalities and clinical parameters.

METHODS

This case-control study included 60 rosacea patients and 20 age- and sex-matched healthy individuals. Patients were grouped as untreated, topically treated with metronidazole, or systemically treated with doxycycline plus metronidazole. Serum PCT levels were measured by fluorescence immunoassay. Statistical analyses included Kruskal-Wallis, Mann-Whitney U, and multivariate linear regression.

RESULTS

Rosacea patients had significantly higher PCT levels than controls (0.18 ± 0.06 vs. 0.12 ± 0.04 ng/mL; p < 0.001). Elevated PCT was observed in untreated and topical-only groups, while systemic treatment was associated with reduced levels (0.10 ± 0.004 ng/mL; p < 0.001), comparable to controls. No differences were found based on sex, smoking, or alcohol use. Multivariate analysis identified systemic therapy as a negative predictor (β = -0.55, p < 0.001) and papulopustular subtype as a positive predictor of elevated PCT (β = 0.23, p = 0.039).

CONCLUSIONS

PCT may reflect underlying subclinical inflammation in rosacea and decrease with systemic therapy. These findings support further investigation of PCT as a biomarker in rosacea.