Biologic therapy increases Demodex density in psoriasis patients

Background Demodex density is known to increase in various immunosuppressive conditions. The relationship between biologic therapy and Demodex density remains unknown. We aimed to investigate whether the density of Demodex mites is higher in psoriasis patients treated with biologic agents compared to treatment‐naive or topically treated patients. Methods A cross‐sectional study was conducted, comparing psoriasis patients receiving biologic therapy (n = 34) with controls (n = 33). Demodex density was assessed using the standardized skin surface biopsy technique (SSSB). Statistical analysis was performed to compare the densities and prevalence of demodicosis between the two groups. Results Demodex density was significantly higher in the biologic therapy group compared to the control group on the right cheek (7.29 vs. 0.12/cm2; P = 0.001), left cheek (8.15 vs. 0.24/cm2; P = 0.002), and whole face (average of all four regions: 5.50 vs. 0.80/cm2; P = 0.001). The prevalence of demodicosis was significantly higher in the biologic therapy group on the forehead (35.3% vs. 12.1%; P = 0.043), right cheek (41.2% vs. 0%; P