Narrowing the Gap Between Diagnosis of Psoriasis and Psoriatic Arthritis

For many patients with psoriasis, the possibility of developing psoriatic arthritis (PsA) is a looming concern, as findings have shown that as many as one-third of patients with psoriasis ultimately progress to PsA.¹

Despite these high rates, there are often significant delays in the diagnosis of PsA in this population. A retrospective cohort study that included 164 patients published in the Journal of Rheumatology found that more than half of patients with PsA experienced diagnostic delays exceeding 2 years (median time, 2.5; IQR 0.5-7.3) following the onset of PsA-related joint symptoms. Logistic regression analysis revealed that such gaps were less likely to affect patients with sebopsoriasis, while younger age at symptom onset, enthesitis, and higher BMI were linked to diagnostic delays of more than2 years.²

Reasons for Delayed Diagnosis

There are various causes for the diagnostic delays in this population, on both the patient and physician level. “People often focus on their visible issues and attribute their ‘aches and pains’ to other reasons, such as getting older or an old sports injury acting up, rather than PsA,” explained Lisa A. Mandl, MD, MPH, rheumatologist at Hospital for Special Surgery and assistant research professor of medicine and public health at Weill Cornell Medical College in New York.

“Many people don’t realize there is a connection between inflammation in their skin and inflammation in their joints.” In addition, normal blood test results, which are common tests in patients with PsA, may be interpreted as an indication that PsA is not present even if initially suspected.³

Ambiguity in the presentation of PsA compared to psoriasis represents another major factor that can delay recognition of the disease.³ “While cutaneous psoriasis is easily visible on the skin and does not tend to have too much overlap in appearance with other rashes, psoriatic arthritis can be subtle and difficult to distinguish from other forms of arthritis and can affect a wide variety of joints,” stated Sara Lamb, MD, assistant professor of dermatology at Johns Hopkins University School of Medicine in Baltimore, Maryland.

In a recent survey by Health Union, a company that manages hundreds of condition-specific online patient communities, 61% of patients with psoriasis indicated that their physician had not even discussed with them the risk for developing PsA.⁴

“Many dermatologists do not feel comfortable with making the diagnosis,” said Richard Gallo, MD, PhD, the Ima Gigli Distinguished Professor of Dermatology and founding chairman of the department of dermatology at the University of California, San Diego, School of Medicine. This can contribute to diagnostic delays, thus increasing the risk for “unnecessary discomfort for the patient, decreased quality of life, and a lack of adequate treatment.”

Improving Detection of PsA

However, dermatologists are positioned to ensure early detection of PsA, which is crucial in preventing progression of the disease and the resulting irreversible joint destruction.⁴ To that end, it is important to ask patients with psoriasis about PsA symptoms at each visit, and to obtain imaging and involve a rheumatologist at the first sign of joint stiffness, pain, or swelling suggestive of PsA, according to Dr Lamb. Tenosynovitis and enthesitis on ultrasound have been cited as key imaging features indicating an elevated risk for developing PsA in patients with psoriasis.⁵

Dr Gallo recommends that dermatologists “include a complete history of joint symptoms and consider early involvement of rheumatology colleagues to rule out other causes and follow progress during treatment.”

Dr Mandl encourages physicians to think of PsA “if joints are red or swollen – particularly the distal interphalangeal joints of the hand, if the toes or fingers are swelling up like sausages, or if patients complain of pain that is worse in the morning and gets better during the day.” Dactylitis reportedly affects up to 48% of patients with PsA.⁴ She also advises referral to a rheumatologist if patients have joint or back pain.

Treatment needs may shift for patients with psoriasis who develop PsA, Dr Lamb emphasized. “Clinicians should be aware that some treatments for cutaneous psoriasis, such as narrow band UVB and topical steroids, are not effective for PsA, and thus the patient’s treatment may need to be changed if they develop arthritis as well.” 

Future Directions

To bridge the gap between psoriasis and PsA diagnosis, experts point to a range of remaining needs. These include education to the public to help improve recognition of psoriasis and education to primary care providers to increase referral to a rheumatologist when PsA is suspected, Dr Mandl said. Dr Lamb added that “better education of dermatologists on how to evaluate for psoriatic arthritis would also be very beneficial, especially if access to rheumatology is limited.”

In addition to the ongoing research on disease-modifying drugs for PsA treatment, there is a need for “more research on nonpharmacologic care such as diet, exercise, and the best multi-pronged approached to deal with comorbidities such as obesity that are more likely to be present in people with PsA,” Dr Mandl said.

Finally, studies aiming to identify a biomarker for early PsA detection are warranted, Dr Gallo noted.

References

1. Scher JU, Ogdie A, Merola JF, Ritchlin C. Preventing psoriatic arthritis: focusing on patients with psoriasis at increased risk of transition. Nat Rev Rheumatol. 2019;15(3):153-166. doi:10.1038/s41584-019-0175-0

2. Karmacharya P, Wright K, Achenbach SJ, et al. Diagnostic delay in psoriatic arthritis: a population-based study. Published online February 15, 2021. J Rheumatol. doi:10.3899/jrheum.201199

3. Gottlieb A, Merola JF. Psoriatic arthritis for dermatologists. J Dermatolog Treat. 2020;31(7):662-679. doi:10.1080/09546634.2019.1605142

4. Health Union. Psoriasis and psoriatic arthritis in America 2021 survey. April 2021.

5. Zabotti A, Tinazzi I, Aydin SZ, McGonagle D. From psoriasis to psoriatic arthritis: Insights from imaging on the transition to psoriatic arthritis and implications for arthritis prevention. Curr Rheumatol Rep. 2020;22(6):24. doi:10.1007/s11926-020-00891-x

This article originally appeared on Dermatology Advisor