Understanding the evolution of PsA: A guide for clinicians
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[You] have to have high clinical suspicion to be able to diagnose PsA at early stages.
—Abhijeet Danve, MBBS, MD, MHS
There is the need for early, aggressive treatment to prevent this irreversible joint destruction.
—Colin Edgerton, MD
About 2.4 million Americans live with psoriatic arthritis (PsA), while it’s estimated that more than 15% of people who have psoriasis alone may also have undiagnosed PsA. []
Eventually, about 30% of psoriasis patients will go on to develop PsA. For many patients, the disease severely hinders functionality and overall quality of life. [] To make matters worse, it’s a tricky disease to diagnose accurately and quickly.[]
“[You] have to have high clinical suspicion to be able to diagnose PsA at early stages,” says Abhijeet Danve, MBBS, MD, MHS, a rheumatologist and associate professor of medicine (rheumatology, allergy & immunology) at Yale Medicine.
“Psoriatic arthritis is a heterogeneous condition and can present in different ways. These include distal predominant arthritis, asymmetrical oligoarthritis, axial involvement, enthesitis, dactylitis, and, rarely, arthritis mutilans,” he notes.
Diagnosis gap: Early disease recognition
It’s important for clinicians to know how to differentiate PsA at initial presentation from PsA that is more advanced. As it turns out, many docs struggle to do this: About 50% of doctors gave a wrong answer when we asked them, “How does PsA look at the beginning of the disease vs when it progresses?”
Dr. Danve says, “Early in the disease course, joint stiffness, enthesitis, dactylitis, and fatigue are common features."
In the beginning, patients tend to experience asymmetric oligoarticular arthritis—meaning only four or fewer joints are affected. [] “Most patients have long-standing skin psoriasis,” Dr. Danve adds. “Those with nail involvement are at high risk of distal interphalangeal joint arthritis.”
When the disease progresses, patients will show different symptoms: “In late disease, patients develop obvious joint swelling, limited range of motion, joint damage, and deformities if untreated,” Dr. Danve explains. At this point, polyarticular arthritis sets in, meaning it affects 5 or more joints. []
“In later disease, comorbid conditions like obesity, fatty liver, and hypertension are more common,” Dr. Danve adds. Patients with these comorbidities typically experience not only severe disease and poorer quality of life, but also increased risk of quitting treatment. []
A practical guide for the clinic
Early PsA
Joint stiffness
Enthesitis
Dactylitis
Fatigue
Asymmetric oligoarticular arthritis (≤ 4 joints affected)
Long-standing skin psoriasis
Nail involvement (higher risk of DIP joint arthritis)
PsA that has progressed
Obvious joint swelling
Limited range of motion
Radiographic joint damage
Joint deformities (if untreated)
Polyarticular arthritis (≥ 5 joints affected)
More common comorbidities (obesity, fatty liver, hypertension)
Early diagnosis may not preclude joint damage
Even if you do catch a patient’s PsA early on, there’s still a risk of damage. Nearly half of patients will develop bone erosions, even when being treated by disease-modifying antirheumatic drugs (DMARDs), says Colin Edgerton, MD, a board-certified rheumatologist and co-founder of Articularis Healthcare Group. About a quarter of patients already will present to your office for the first time with at least one area of radiographic damage.
Related: 50% of PsA patients show early damage: What does that mean for treatment?“This highlights the need for early, aggressive treatment to prevent this irreversible joint destruction,” he notes.
Accurately diagnosing PsA is vital. Since there’s no single blood test for PsA, you need to look out for the signs and be able to distinguish between diseases: In PsA, a patient’s joint pain and swelling would be asymmetric, and involve different joints than, say, the joints involved in rheumatoid arthritis. Paying attention to the entheses is also important. [] Spine pain may also open the door to the possibility of axial psoriatic arthritis.