To date, very few studies have evaluated the feasibility of setting up a specialized PsA center. In fact, this kind of structure with very close cooperation of dermatologists and rheumatologists is limited mostly to university hospitals. The aim of our PsA center is to optimize the medical care for psoriasis patients with suspected PsA in a team-oriented approach.
The direct referral of patients with suspected PsA to the specialized PsA center can help to overcome the confusion between arthritis diagnosis and treatment in patients, thus increasing the attention of patients to management and follow-up in this specialized center. The PsA center’s most critical priorities are the early diagnosis and treatment of PsA. PsA, if left untreated, can result in irreversible joint deformity causing immobility and worsening the overall well-being issues .
Differential diagnosis is sometimes complex and early management is difficult, requiring the aid of a rheumatologist. There are many studies underlying the delay in diagnosis and treatment of PsA, which typically leads to different orthopedic operations until these patients finally are diagnosed [10, 11]. Previous studies also suggested, that there are significant deviations in clinical management and follow-up of patients with psoriasis and PsA, depending on the specialist they initially choose to see, often leading to misdiagnosis and sometimes loss of diagnosis, decreasing the compliance of the patient [12,13,14]. In addition, in a specialized PsA center, rheumatologists are acquainted with topical therapies used in dermatology as well as with the dermatological view of systemic therapies concerning the efficacy in plaque psoriasis. In the PsA center, severity of skin changes are carefully assessed by the dermatologist and reported to the rheumatologist, so that both can decide on a common therapeutic algorithm, tailored for each patient. Furthermore, we can learn more about paradoxical reactions on the skin due to different biological therapies, which could be addressed in an interdisciplinary setting.
In patients with PsA, a positive family history for psoriasis was present in 37.86%. Although, patients with PsA are usually negative for RF, elevated levels were found in 6 cases (5.83%) . A similar percentage was observed in patients with psoriasis probably relating to similar presence in the general population .
Our data did not show significant differences in PASI, DLQI, GEPARD and CASPAR scores between patients with psoriasis and PsA. The GEPARD questionnaire (mean ± SD: Psoriasis = 6.7 (±3.3), PsA = 8.2 (±2.7)) and the CASPAR classification criteria (mean ± SD: Psoriasis = 5.1 (±1.8), PsA = 5.8 (±1.7)) which are commonly used, were not found to be helpful for differentiating between psoriasis and PsA. This is commonly observed in clinical practice, although the literature suggests a better diagnostic yield [17, 18]. Despite this, the higher level of DLQI in patients with PsA, which primarily affects the impact of the skin symptoms on health-related quality of life, indicated a greater degree of impairment in those patients . On the other hand, the dermatologist should not stop asking for joint complaints in psoriasis patients as PsA is often developed in the later history of psoriasis .
Plaques psoriasis (86.41%) was the most common type of psoriasis in PsA patients. Current literature underlines our observation, as a 2–3-fold higher risk of developing PsA in patients with scalp lesions, nail dystrophy and perianal lesions is described . Our patients with PsA reported scalp involvement in 49.51%, rima ani involvement in 48.54% and nail involvement in 42.72%, so no specific form of psoriasis was found to be linked to PsA.
Our study yielded a similar increase in prevalence of comorbidities as published, highlighting cardiovascular diseases, gastrointestinal, psychiatric and neurological diseases in psoriasis and PsA .
A total of 43 patients out of 373 (11.5%) were diagnosed with another rheumatological disease than PsA, underlining the significance of the dermatological-rheumatological approach not only in PsA.
Non-rheumatological diseases were diagnosed in 67 patients out of 373 (18%). In 55 (15%) patients OA was diagnosed, which was first diagnosed in 50 (13%) patients whereas PsA was diagnosed in 103 cases (28%). This underlines the complexity of differentiating OA from PsA for dermatologist. Although, we assessed significant differences in the history of arthralgia (p = 0.0407), swollen joints (p = 0.0151), morning stiffness of the digits (p = 0.0451) and dactylitis (p = 0.0086), tender joints and pain insomnia did not play prominent roles. These symptoms and clinical signs can help to distinguish between OA and PsA but further diagnostics is required. This emphasizes the difficulty for dermatologists in interpreting joint complaints and that is not described in the literature. Future trials will need to focus more on diagnostic tools such as ultrasound, facilitating the diagnosis of arthritis. An additional validated questionnaire could be another future vision improving the diagnostic yield, but is obviously quite complex, as shown by our results concerning CASPAR classifications criteria and the GEPARD questionnaire.
Data on patient journey in both the periods show that the time taken for diagnosis by the rheumatologist was about 12 months shorter in period 2 after the foundation of the PsA center compared to period 1, which is clinically significant, in order to prevent irreversible damage of the joint.
There are several examples of collaboration between different departments such as uveitis clinics or reproduction and pregnancy clinics in which the patient is seen by various experts for chronic medical complaints [19, 22, 23]. These experiences demonstrate a significant diagnostic and therapeutic benefit. Positive aspects of these specialized centers include avoiding excessive laboratory testing, minimizing the number of visits, efficient decision-making and efficient flow of knowledge leading to fastened diagnosis and procedures for patient management.
Dermatologists and rheumatologists mutually are involved in the management of all overlapping disorders, notably PsA, as they specifically focus on their area of expertise. They see the patients in their respective offices at different times. This form of practice model resulted in the lack of communication and teamwork between specialists . Our practice model not only decreased the duration of rheumatological complaints until request in period 2 but also significantly reduced the days required from consultation request until the consultation. In period 2, patients were seen in average 9 days earlier by the rheumatologist. Although, not investigated in this trial, it is imaginable, that the interdisciplinary consultation is not as time consuming as the single visits of each physician.
The limitations of the study are in regards to the retrospective and the monocentric study design. Future prospective studies are necessary in order to confirm our observations.
One of the greatest benefits of the PsA center is also the inspiration for research provided by the collaboration of both dermatologists and rheumatologists.
It is, to the best of our knowledge, the first study comparing patient management before and after foundation of a joint, dual center focusing on patients with psoriasis and PsA. Our conclusions complement the findings of other research groups worldwide. The importance of service delivery in interdisciplinary teams is illustrated by our data in the taking control of complicated or complex patients, suffering from more than one disease into account.