How can I assess the severity of psoriasis in a patient to guide treatment decisions?

To assess the severity of psoriasis in a patient to guide treatment decisions, follow these steps:

• Assess disease severity at first presentation, before referral, and at each treatment point by recording:
• The static physician's global assessment, classified as clear, nearly clear, mild, moderate, severe, or very severe.
• The patient's own assessment of current disease severity using a similar scale.
• The body surface area (BSA) affected by psoriasis.
• Any involvement of nails, high-impact or difficult-to-treat sites such as the face, scalp, palms, soles, flexures, and genitals.
• Any systemic symptoms such as fever or malaise, which may indicate unstable forms like erythroderma or generalized pustular psoriasis.
• In specialist settings, use validated tools such as the Psoriasis Area and Severity Index (PASI) alongside the above assessments to quantify severity more precisely.
• Use the Nail Psoriasis Severity Index (NAPSI) in specialist care if nail disease has major functional or cosmetic impact or before and after nail-specific treatment.
• Assess the impact of psoriasis on physical, psychological, and social wellbeing by asking about daily living effects, coping, mood, distress, and impact on family or carers.
• Screen for psoriatic arthritis by inquiring about joint pain or swelling, as this affects treatment decisions and may require specialist referral.
• Consider comorbidities and cardiovascular risk, especially in severe psoriasis, and assess these risks using appropriate tools to guide holistic management.

This comprehensive assessment informs treatment choices, monitoring, and referral decisions to optimise patient outcomes.