Hematological parameters as diagnostic biomarkers for patients with rosacea

Rosacea is a chronic inflammatory skin disease. Systemic inflammation plays a vital role in the pathogenesis of rosacea. Many studies have reported hematological parameters as biomarkers for diseases with inflammatory processes. However, the diagnostic value of hematological parameters in rosacea remains a puzzle. This study involved 462 patients with rosacea, including erythematotelangiectatic rosacea (ETR, n = 179), papulopustular rosacea (PPR, n = 250), and phymatous rosacea (PhR, n = 33), and 924 healthy control subjects. Demographic, clinical, and laboratory information was collected and compared between rosacea subtypes. The hematological parameters of the patients and the healthy controls were compared retrospectively. The platelet volume (MPV) and platelet crit (PCT) were significantly upregulated, and the lower red cell distribution width (RDW) was significantly downregulated in rosacea compared to healthy controls, and they were identified as the diagnostic biomarkers for rosacea with area under the curve values of 0.828, 0.742, and 0.787, respectively. Comparing the hematological parameters among the three rosacea subtypes, we found that platelet-to-lymphocyte ratio and platelet-to-neutrophil ratio values in the ETR group were significantly higher than those in the PPR and PhR groups. The correlation between hematological parameters and clinical scores showed that RDW was negatively correlated with the Clinician Erythema Assessment score. However, there was no significant correlation between the Investigator Global Assessment score and hematological parameters. In conclusion, PCT, MPV, and RDW have diagnostic value for rosacea, and RDW is correlated with the severity of rosacea erythema, implying the potential applications of PCT, MPV, and RDW in the diagnosis and monitoring of rosacea.