Erythema Increase Predicts Psoriasis Improvement after Phototherapy

Area of Science:

• Dermatology
• Photobiology
• Skin Physiology

Background:

• Psoriasis is a prevalent global skin condition requiring effective treatment strategies.
• Selecting cost-effective psoriasis therapies necessitates tools to predict patient response.
• Phototherapy is a common treatment, but its precise impact on skin barrier function needs further elucidation.

Purpose of the Study:

• To assess epidermal barrier function and skin homeostasis changes post-phototherapy.
• To identify predictive markers of clinical improvement after phototherapy in psoriasis patients.
• To evaluate the efficacy of phototherapy in improving skin barrier parameters.

Main Methods:

• A comparative study involving 38 psoriasis patients and 38 healthy controls.
• Measurement of erythema, transepidermal water loss (TEWL), stratum corneum hydration (SCH), and pH before and after phototherapy sessions.
• Analysis of changes in skin parameters after the first and fifteenth phototherapy sessions.

Main Results:

• Psoriatic plaques showed significantly higher erythema and TEWL, and lower SCH compared to healthy skin.
• Phototherapy led to a significant decrease in TEWL and an increase in SCH in psoriatic plaques.
• An increase in erythema exceeding 53.23 AU after the first session predicted a ≥3-point improvement in PASI after 15 sessions with high sensitivity and specificity.

Conclusions:

• Phototherapy effectively improves epidermal barrier function in patients with psoriasis.
• Early changes in erythema following the first phototherapy session can serve as a predictive indicator for treatment response.
• This finding aids clinicians in selecting appropriate phototherapy candidates for psoriasis management.