Psoriasis is a fairly common but relatively untreated skin condition that has shown recent advances in treatment.
Psoriasis can cause extreme discomfort associated with itching and painful lesions, which may crack and bleed. More than just a cosmetic problem, psoriasis negatively impacts one's quality of life by disrupting social functioning and emotional well-being. Increased levels of stress, anxiety, and depression caused by psoriasis may actually aggravate the condition, creating a vicious cycle. According to dermatologist David Adams, M.D., Pharm.D., at Pennsylvania State University's Milton S. Hershey Medical Center, it is important for pharmacists to recognize that psoriasis is a condition affecting 2% of the population. "It's more common than we think," he said. "Patients can often hide it with clothing."
According to statistics gathered by the National Institutes of Health, up to 7.5 million American adults suffer from psoriasis, with 150,000 new cases diagnosed each year. Furthermore, approximately one million individuals with this condition are also affected by a form of arthritis called psoriatic arthritis, which is associated with inflammation of the joints and connective tissue. Finger and toe joints are most commonly affected, but the lower back and knees may also be involved.
Some patients may be fortunate enough to experience periods of disease remission, but there is no cure for psoriasis. Thus, effective treatments that manage symptoms on a long-term basis are needed. According to the National Psoriasis Foundation (NPF), nearly 40% of patients with chronic moderate-to-severe psoriasis are not receiving any treatment, and more than half of patients who do get treatment are not receiving treatment in line with American Academy of Dermatology (AAD) guidelines, which are based on disease severity.
Psoriasis severity is most often assessed by how much body surface area (BSA) the disease covers. It is frequently classified as mild, moderate, or severe based upon BSA involvement. This type of classification is used in clinical trials, by physicians making treatment decisions, and by insurance carriers determining drug coverage. However, according to NPF, the current classification system has limitations; it does not take into account the location or the type of psoriasis, the diagnosis of psoriatic arthritis, or the influence of the condition on the patient's quality of life.
Since these other factors can influence disease severity, NPF's medical board has proposed a novel classification system to better reflect how patients are treated in clinical practice. NPF recommends just two categories for classifying psoriasis patients: those who are candidates for topical therapies and those who are candidates for systemic and/or phototherapies. The goal is "to make psoriasis classification more relevant in the real clinical world," said David Pariser, M.D., a dermatology professor at Eastern Virginia Medical School. "Everyone agrees on what constitutes mild and severe disease, but dermatologists and insurance companies argue over moderate psoriasis," he explained. "There are tremendous differences in quality of life for patients with moderate psoriasis on their back versus moderate psoriasis on the bottom of their feet, preventing them from walking." As a result, moderate psoriasis may require vastly different treatment options.
Drugs for psoriasis generally fall into five distinct categories and are often initiated in a tiered approach. "Most people with elbow, knee, and scalp psoriasis can be treated with topical agents," said Adams. "But for others, such as patients with hand and foot psoriasis, aggressive treatment is warranted just so they can perform activities of daily living-even though the disease may cover only a small fraction of body surface area."