• A recent study found phototherapy is most effective in treating psoriasis when it’s used with other treatments.
• Psoralen and ultraviolet A light (PUVA) with calcium and vitamin D derivatives was the most effective treatment combination.

Treating psoriaisis with ultraviolet (UV)-based phototherapy can be improved by adding other psoriasis treatments, according to a recent study.

Phototherapy exposes the skin to UV light to help treat and clear psoriatic lesions. There are two main types of phototherapy, and each uses a different form of UV light. Ultraviolet light B (UVB) is found in natural sunlight. It’s effective for treating psoriasis because it can penetrate into the skin and hinder the growth of psoriatic lesions. Ultraviolet light A (UVA) is also used to treat psoriasis, often with medication known as psoralen that makes the skin more sensitive to light. This combination is known as PUVA — psoralen and UVA — and is used to help slow cell growth and clear the skin.

In addition to phototherapy, topical treatments, oral retinoids, and biologics can be used to help manage and clear psoriasis.

Which Treatments Work With UV Phototherapy?

The study authors set out to compare the safety and efficacy of UV-based phototherapy both alone and in combination with other medications. The researchers performed a meta-analysis of 32 clinical trials, which included 2,120 people with psoriasis.

The authors found five main treatment plans using phototherapy alone or together with other treatments (referred to as adjuvant therapy). These included:

• UVB alone
• PUVA alone
• UVB plus adjuvant therapy
• PUVA plus adjuvant therapy
• UVB plus PUVA

The therapies’ effectiveness was measured by how many study participants achieved a Psoriasis Area and Severity Index (PASI) 75 response while taking them. PASI is a tool used to measure the extent and severity of a person’s psoriasis. PASI 75 means a person’s score decreased by 75 percent from their original, baseline score — which is a large reduction in disease severity.

The safety of the therapies was measured by determining how many people withdrew from a study due to unwanted side effects.

Overall, the therapies that offered the best chance for a PASI 75 response were UVB phototherapy with adjuvant therapy and PUVA with adjuvant therapy. Both were more effective than phototherapy alone, and the addition of adjuvant therapy posed no safety risks. The combination of PUVA with calcium and vitamin D derivatives was the safest and most effective treatment across all of the clinical trials studied.

The authors concluded that UVB or PUVA with adjuvant therapy “especially combined with calcium/vitamin D derivatives, are both safe and effective treatments for psoriasis and have the potential for the first choice in the treatment of moderate-to-severe psoriasis.”

The researchers emphasized that more trials are needed to better understand the best phototherapy treatments for people with psoriasis.