Diagnosing PsA: Combining Methodologies Studied Within a Rapid Access Clinic

In a study that compared the effectiveness of different procedures for diagnosing psoriatic arthritis (PsA) among patients with psoriasis (PsO) who were experiencing musculoskeletal complaints, researchers found that adding targeted musculoskeletal ultrasound (MSK‐US) to PsA screening questionnaires yielded better combined specificity and sensitivity.

In a rapid access clinic, patients with PsO but without a previous diagnosis of PsA were asked to assess their musculoskeletal symptoms according to 3 determinations: an assessment by an advanced practice physiotherapist; a targeted musculoskeletal ultrasound (MSK‐US); and PsA screening questionnaires.

A rheumatologist then assessed these patients to classify their symptoms as “Possibly PsA,” “PsA,” and “Not PsA.” Participating patients returned after 1 year for a follow-up visit to determine any change in disease activity. The researchers also assessed sensitivity and specificity for each modality.

Of the 203 patients with PsO and musculoskeletal symptoms enrolled in the study, 8.8% were classified with PsA, and 23.6% were determined to be “possibly PsA.” No significant difference was determined among the individual modalities. While the greatest sensitivity was evident with MSK‐US at 89%, the Psoriatic Arthritis Screening and Evaluation (PASE) questionnaire demonstrated the highest specificity at 79%.

“The addition of MSK‐US data improved the performance of the modalities. A total of 9 patients converted to PsA after 1 year. All patient-reported outcome measures have significantly improved at one year (P<0.001),” concluded the authors. “Combining MSK‐US with a screening questionnaire for PsA improved the triage of patients with suspected PsA.”


-Angelique Platas


Sarabia S, Farrer C,  Yeung J, et al.  Comparative efficacy of different triage methods for psoriatic arthritis – prospective study in a rapid access clinic. Arthritis Care Res. Published online February 5, 2021. doi.org/10.1002/acr.24570.