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Study validates use of new psoriatic arthritis prediction tool



A new predictive tool known as the Psoriatic Arthritis Risk Estimation Tool (PRESTO) is now available to help clinicians estimate the risk of psoriatic arthritis (PsA) in their patients with psoriasis.

Though it requires further validation, researchers led by rheumatologist Lihi Eder, MD, PhD, of the Women’s College Research Institute at Women’s College Hospital, Toronto, characterized the development and validation of PRESTO as “an important first step in the development and testing of interventional strategies that may ultimately halt disease progression,” they wrote in their study of the tool, which published in Arthritis & Rheumatology. Dr. Eder presented a summary of progress on the effort at the 2023 annual meeting of the Canadian Rheumatology Association.

Dr. Lihi Eder, codirector of the cardio-rheumatology program at Women's College Hospital in Toronto

Dr. Lihi Eder

To develop and validate the tool, the researchers evaluated 635 patients from the University of Toronto Psoriasis Cohort, which was launched in 2006 as a prospective longitudinal cohort study to examine risk factors for the development of PsA among patients with psoriasis. Patients enrolled in the cohort have a dermatologist-confirmed diagnosis of psoriasis and are assessed by a rheumatologist prior to enrollment to exclude those with inflammatory arthritis in the past or at the time of assessment.

To develop prediction models for PsA, Dr. Eder and colleagues used information from the patient cohort demographics, psoriasis characteristics, comorbidities, medications, and musculoskeletal symptoms. Next, they used multivariable logistic regression models adjusting for covariates, duration of psoriasis, and the log duration at risk to estimate the probability of developing PsA within 1-year and 5-year time windows from consecutive study visits.

The mean age of the study participants was 47 years, 76% were White, and 57% were male; and they had psoriasis for a mean of 16 years. The researchers found that 51 patients developed PsA during the 1-year follow-up, and 71 developed PsA during the 5-year follow-up. The risk of developing PsA within 1 year was associated with younger age, male sex, family history of psoriasis, back stiffness, nail pitting, joint stiffness, use of biologic medications, patient global health, and pain severity (area under the curve, 72.3).

In addition, the risk of developing PsA within 5 years was associated with morning stiffness, psoriatic nail lesions, psoriasis severity, fatigue, pain, and use of systemic non-biologic medication or phototherapy (AUC, 74.9). Calibration plots showed reasonable agreement between predicted and observed probabilities.

“Interestingly, several previously reported risk factors for PsA, such as HLA-B27, family history of PsA, uveitis, and flexural psoriasis, were not included in the risk prediction model due to their scarcity in our cohort,” the researchers wrote. “This finding may be due to immortal time bias which can complicate the development of risk prediction models for PsA. Genetic factors or their surrogates (e.g., family history of PsA) are associated with the development of PsA concurrently or shortly after the onset of psoriasis.”

They acknowledged certain limitations of the study, including its relatively small sample size and questionable generalizability of the study findings, “as most of the patients were recruited from dermatology clinics leading to overrepresentation of moderate-severe psoriasis. Therefore, PRESTO will require an external validation to assess its performance in other populations of psoriasis patients with different characteristics.”

Saakshi Khattri, MD, a board-certified dermatologist, rheumatologist, and internist at the Icahn School of Medicine at Mount Sinai, New York, who was not involved in the study and was asked to comment on the results, characterized the PRESTO tool as “an interesting step in the right direction, but it’s the first step.”

Dr. Saakshi Khattri, dermatologist, rheumatologist, and internist, Mount Sinai, New York. courtesy Dr. Saakshi Khattri

Dr. Saakshi Khattri

Since dermatologists are usually the first point of contact for psoriasis patients, she added, “a risk calculator can be helpful, but the question remains: When do we refer them to a rheumatologist? If the risk comes to 5%, is that a low risk that doesn’t need referral to rheumatology? I don’t think those questions have been answered here. From a rheumatology perspective, does the risk calculator help me decide when to intervene? At present, I’m not sure it does. Perhaps a higher score might make us intervene sooner if our clinical exam doesn’t show swollen or tender joints.”

Clinical exam findings and history she considers as a rheumatologist before making treatment recommendations include the following: Are there swollen and tender joints? Does the patient report morning stiffness for upwards of 30 minutes? Do they have enthesitis or dactylitis? Is there axial involvement? “Imaging can help if there isn’t anything on clinical exam and the history is compelling and/or the patient has risk factors for PsA,” she said.

The study’s finding of biologic use being associated with risk of developing PsA at year 1 but not at year 5 is “confusing,” Dr. Khattri added. “My concern is, will that now dissuade our moderate to severe psoriasis patients from using biologics to clear their psoriasis? We know that biologics are indicated for moderate to severe psoriasis. We also know psoriasis is associated with increased cardiovascular risk and there’s data to suggest that treatment with biologics with its resultant decrease in systemic inflammation can decrease cardiovascular risk.”

The study was supported by a New Investigator Grant from the Physician Services Incorporated Foundation. Dr. Eder disclosed that she is supported by the Canada Research Chair in Inflammatory Rheumatic Diseases. Dr. Khattri reported that she is a member of the advisory board for UCB, Janssen, AbbVie, Regeneron, Sanofi, Lilly, Argenx, and Arcutis. She has also received research funds from Incyte, AbbVie, Leo, Galderma, Pfizer, and Acelyrin.

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