**4. Discussion**

We identified several clinical features of PsA based on the results of this study. First, PsA dominantly afflicted male patients (77%), with the mean age of onset for cutaneous psoriasis at 36.8 years, while that of osteoarticular lesions at 47.0 years. Second, the skin leading type was observed more than the osteoarticular leading type, with the interval between the onset of both symptoms significantly shorter in the osteoarticular leading type than in the skin leading type. Third, upper extremity lesions were more dominant (53 cases; 83%) than lower extremity lesions (30 cases; 47%). Fourth, axial lesions were observed in 33% and enthesitis in 23% of the sample. Fifth,

#### *The Clinical Characteristics and Treatment Status of Psoriatic Arthritis DOI: http://dx.doi.org/10.5772/intechopen.102077*

obesity was strongly associated with PsA. Finally, csDMARDs were the most prescribed drugs in patients with PsA, followed by bDMARDs and NSAIDs.

Regarding the onset pattern of PsA in a Japanese multicenter study, Ohara reported arthritis preceded psoriasis in 11% of patients [1]. In previous reports concerning PsA [3–6], the incidences of "joint before skin" cases were between 15% and 30% of the sample. In our study, arthritis preceded skin lesions in 17%, which was in near agreement with the results of previous reports. In these cases, the lack of skin lesions makes diagnosis difficult.

Regarding the distribution of arthritis, Ritchlin reported that axial joints are affected in 50% of PsA patients [2]. In the Japanese multicenter study, back pain such as lumbago and neck pain was observed in 34.3% of patients and enthesitis in 28.3% [10, 11]. Similarly, our study showed that axial lesions were present in 33% and enthesitis in 23%.

Moreover, we checked the distribution of arthritis by the onset patterns in this study. However, there was no statistically significant difference in both peripheral and axial lesions, and it was therefore concluded that the distribution pattern was not useful for detecting PsA in the osteoarticular leading type.

The risk factors for the development of psoriasis are obesity and lifestyle-related diseases such as hypertension, diabetes mellitus, hyperlipidemia [12], with obesityrelated to the severity of psoriasis [13]. A large cohort study also demonstrated that BMI was associated with psoriasis [14]. In another study, PsA showed a significant association with obesity, type 2 diabetes, hypertension, metabolic syndrome, fatty liver, and an increased risk of cardiovascular events [15].

Similarly, in our study, obesity was significantly associated with PsA; however, the other factors were not statistically significantly associated with PsA.

Regarding the treatment status, NSAIDs were effective for joint symptoms but ineffective for skin lesions. The csDMARDs were effective for arthritis and skin involvement, whereas the bDMARDs were used for patients with an inadequate response to the csDMARDs as it can suppress skin and joint inflammation and delay radiographic progression.

Despite the use of traditional disease-modifying medications in more than 50% of patients with PsA, bone erosions were still observed in 47% of patients within the first 2 years [16]. Therefore, the appropriate diagnosis of PsA and tight control are required for better clinical outcomes of PsA. According to the American College of Rheumatology recommendation for PsA in a 2019 update, non-steroidal anti-inflammatory drugs and local glucocorticoid injections are proposed as initial therapy. Further, for patients with arthritis and poor prognostic factors such as polyarthritis or monoarthritis/oligoarthritis accompanied by factors such as dactylitis or joint damage, rapid initiation of csDMARDs are recommended. If the treatment target is not achieved with this strategy, bDMARDs targeting tumor necrosis factor (TNF), interleukin (IL)-17A, or IL-12/23 should be initiated [17].

In our study, NSAIDs were used in 39% of patients, csDMARDS in 64%, and bDMARDs in 51.5%. These data suggest that skin or arthritic symptoms were moderate to high in our cases. Yamamoto et al. Demonstrated that bDMARDs were used in more than 50% of all patients registered with PsA, which is in agreement with our results [10, 11].

Our study had several limitations. First, the small sample size was a result of this study taking place at a single center. Second, the type of skin and severity of psoriasis with a Psoriasis Area and Severity Index score was not evaluated. Third, the effect of the prescribed drugs was not examined.
