To the Editor:
The importance of enthesitis as the key pathological lesion underpinning the pathogenesis of psoriatic arthritis (PsA) has been increasingly recognized1. Studies for more than 3 decades have shown a high frequency of osseous and entheseal abnormalities in patients with psoriasis without clinical signs of arthritis2,3. From a clinical viewpoint, about 10% of patients with psoriasis develop PsA over a decade, so there is a need to better define predictive factors for the identification of future PsA in patients with psoriasis4. The ability to accurately predict development of PsA in subjects with psoriasis could have implications for prevention of the morbidity associated with PsA and also for studies aimed at elucidation of the early phases of disease.
We previously used ultrasound (US) to show a high frequency of subclinical entheseal involvement in patients presenting with psoriasis but without clinically evident arthritis5. We investigated whether subclinical enthesopathy in patients with psoriasis predicted the future development of PsA.
A longitudinal evaluation was performed in a cohort of 30 cases of psoriasis with a mean duration of 3.5 years using clinical and repeat ultrasound assessment of lower-limb tendons, using the Glasgow Ultrasound Enthesitis Scoring System (GUESS)6. Of the 30 patients originally evaluated5, 28 returned for a re-evaluation. No patient received systemic treatment with a disease-modifying antirheumatic drug. The criteria of the ClASsification of Psoriatic ARthritis (CASPAR) study group were used to define the presence or absence of PsA7. Evidence for osteoarthritis (OA) was also sought, as this can affect the same joints involved in PsA, including distal interphalangeal (DIP) …
Address correspondence to Dr. I. Tinazzi, Unit of Rheumatology, University of Verona, P.le Scuro 1, 37134 Verona, Italy. E-mail: ilariatinazzi{at}yahoo.it