Why BSA Alone Underestimates Psoriasis Severity

Amanda Caldwell, MSN, APRN-C, outlined a comprehensive approach to psoriasis assessment during a recent Dermatology Times interview, emphasizing that disease severity cannot always be captured by body surface area (BSA) alone. She discussed the importance of evaluating special-site involvement, associated comorbidities, and the functional and psychosocial effects of psoriasis, as well as incorporating patient preferences into treatment selection.

Assessing Disease Burden Beyond BSA

Caldwell described psoriasis as a chronic immune-mediated, multisystem disease rather than solely a visible skin condition. Assessment, she said, should consider not only how much skin is affected but also where lesions occur, how they affect the patient's daily life, and whether signs of associated disease are present.

“Psoriasis is not simply just a visible skin disease; it's a chronic immune-mediated multisystem disease,” Caldwell said.

BSA alone can underestimate disease severity, particularly when psoriasis affects high-impact or special sites. The scalp, nails, genitals, palms, soles, and face may account for relatively little total surface area while still creating substantial functional or psychosocial burden.

Caldwell recommended asking patients about symptoms and quality-of-life effects that may not be apparent during a skin examination, including itch, pain, sleep, work, clothing choices, exercise, intimacy, and emotional well-being.

“What we see is just really a very small percentage of that,” she said.

Looking Beyond the Skin

Because psoriasis is associated with systemic disease, Caldwell emphasized looking for signs of comorbidities as part of routine assessment.

She encouraged clinicians to ask about potential joint involvement, including morning stiffness and symptoms suggestive of dactylitis or enthesitis, including Achilles tendon involvement. She also highlighted the importance of considering the broader comorbidity burden, including cardiovascular and gastrointestinal disease.

The goal, Caldwell explained, is to understand the patient's disease beyond what is immediately visible during an examination.

Expanding Treatment Options Through Shared Decision-Making

Caldwell said she is encouraged by the continued development of highly targeted therapies and the growing number of ways patients can receive psoriasis treatment. She highlighted emerging oral approaches targeting the IL-23 pathway as an area of particular interest.

“What excites me is the continued movement towards highly targeted therapies and having more choices in how patients receive their treatment,” Caldwell said.

Those additional options also create opportunities for greater shared decision-making. Caldwell said clinicians can help patients understand psoriasis, its associated comorbidities, and the treatments available to them, then discuss the advantages and disadvantages of each option based on individual circumstances.

“I love having a discussion with patients and making each visit a shared decision-making process,” she said.

Route of administration can be an important part of that conversation. Some patients remain reluctant to use injectable medications, Caldwell noted, whereas others who already take several medications may be hesitant to add another oral therapy.

“Some are very adverse still to shots, and even in a GLP-1 world, some people either don't want another shot or their pillbox is full,” Caldwell said. “I hear that all the time: I don't want another oral medication.”

Having multiple therapeutic options allows clinicians and patients to weigh those preferences alongside clinical considerations. Caldwell said helping patients choose a treatment they feel comfortable with may ultimately support long-term adherence.

“It's so wonderful to have options, and to be able to help patients make a decision that they feel confident about is only going to help lead to more compliance,” she said.