As dermatologists and patients already know, psoriatic arthritis (PsA) is a serious and potentially debilitating disease. While estimates vary, PsA is thought to develop in as many as 30% of patients with psoriasis.1 Notably, patients can develop PsA independent of the severity of their psoriasis. A National Psoriasis Foundation (NPF) survey found that greater than 50% of patients with PsA had mild or moderate psoriasis.2 While a study by Wilson et al3 found that patients with greater than or equal to three psoriatic sites, including nail dystrophy, scalp lesions, and intergluteal/perianal psoriasis, are twice as likely to develop PsA, this could be due to these locations of disease vs severity.
Patients often present with inflammatory arthritis of the joints, such as the hands, feet, knees, wrists, and elbows, that can appear to be similar to rheumatoid arthritis, but patients may also present with inflammatory arthritic symptoms involving the spine, as such with ankylosing spondylitis.4 Skin lesions precede the development of PsA in 64.5% of patients4 in an average of 7 to 12 years.5
In its discussion of PsA, the American Academy of Dermatology and NPF joint guidelines state that patients with signs and symptoms suspicious for PsA should be fully evaluated for the disease.4 However, modern medicine still lacks a definitive diagnostic test for PsA, of which a delay in diagnosis and treatment can cause undue pain, irreparable joint damage, and significant loss in patient quality of life.6
In their 2020 Winter Clinical Dermatology Conference session titled “A Timely Intervention: Early Clues to Identify the Patient With PsO at Risk of PsA,” Alice B. Gottlieb, MD, PhD, and Joseph F. Merola, MD, MMSc, emphasized the importance of early diagnosis, and subsequently interventions, in preventing the progression of PsA.7 As dual board-certified dermatologist-rheumatologists, their presentation offered a unique perspective on how dermatologists can play a key role in diagnosing PsA within their own practices.
“Psoriatic arthritis,” explained Dr Gottlieb, “is our most common comorbidity, occurring on average in about 30% of patients. Generally, patients mostly present with skin disease before their joint disease, which occurs on average about 10 years in advance.”
She continued that patients do not often recognize that their aches and pains can be due to PsA. “They don’t even know that [dermatologists] can do something about it, and they won’t bring it up unless we ask, and sometimes unless we touch them and assess it.”
“I feel really strongly about the dermatologist playing a key role in the prevention and visibility of psoriatic arthritis,” said Dr Gottlieb. “The dermatologist plays a key role because we get [patients] early in their disease and we want to prevent them from ever getting a swollen, deformed joint. We don’t want to wait until that happens; we want to get it early in the disease, intervene, and prevent any bad consequences from getting psoriatic arthritis.”
The two experts shared a few simple ideas dermatologists should keep in mind when screening for PsA in their next appointment with their patient with psoriasis.
Early and Simple Screening
In their presentation, Drs Merola and Gottlieb shared a simple mnemonic based on a 2015 article by Cohen et al.8 It is a quick and simple process, Dr Merola stated, to complete the “PsA” mnemonic during a visit from a patient with psoriasis. If two or more of the following factors are present on examination, then a more formal screening for PsA should be completed:
P: Pain in joints
S: Stiffness (eg, after waking up or after a period of inactivity >30 minutes), swelling and/or sausage digit (dactylitis)
A: Axial involvement (eg, back pain associated with stiffness)
A similar simple tool has been approved for use by the NPF.9 This screening handout, the Psoriasis Epidemiology Screening Tool (PEST), is a validated tool10 that patients can fill out individually before or between appointments. It consists of five simple yes/no questions (eg, Have you ever had a swollen joint [or joints]?) and a labeled diagram of a body that patients can check off where they feel tender or sore. The NPF indicates that patients who check “yes” to three or more questions should undergo further screening for PsA.