In the method where tenderness and swelling in 28 joints are recorded, known as the Disease Activity Score (DAS 28), global pain assessment score is used along with CRP (C-Reactive Protein) or ESR (Erythrocyte Sedimentation Rate) values. Scores of 2.6 or lower are considered remission, while scores between 2.6 and 3.2 indicate low disease activity, scores between 3.2 and 5.1 indicate moderate disease activity, and scores above 5.1 indicate high disease activity.

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score consists of six questions in the form of a visual analog scale (VAS) related to the five main symptoms of Ankylosing Spondylitis over the past week: fatigue, spinal pain, peripheral joint pain/swelling, localized tenderness, and morning stiffness. A final score between 0 and 10 is obtained. A BASDAI score of 4 or higher is considered indicative of active disease.

The Disease Activity Index for Psoriatic Arthritis (DAPSA) score involves a joint examination of the patient. 68 joints are assessed for tenderness, and 66 joints for swelling. The numbers of tender and swollen joints are determined. The physician evaluates the patient's overall pain during examination and scores it out of 10. The patient's Visual Analog Scale (VAS) value is also recorded. The CRP value is noted.

The score is then calculated simply by summing up all these values (number of tender joints + number of swollen joints + physician's assessment of overall pain + VAS + CRP).

A score between 0 and 4 indicates remission, 5 to 14 indicates low disease activity, 15 to 27 indicates moderate disease activity, and a score greater than 28 indicates high disease activity.

The Psoriasis Area Severity Index (PASI) evaluates both the severity and extent of psoriasis lesions on four body regions: the scalp, arms, trunk, and legs. It assesses the percentage of body surface area affected by lesions (A=area score; 1=<10%, 2=10-29%, 3=30-49%, 4=50-69%, 5=70-89%, 6=90-100%) and the severity of erythema (E), induration (I), and desquamation (D), each scored from 0 to 4.

PASI scores range from 0 to 72, with higher scores indicating more severe disease.

All participants included in the study will undergo sonographic examination using the Logiq 9 (GE, USA) ultrasound device and a high-frequency 7-12 MHz linear probe available in our clinic. The distance between the bilateral spina iliaca anterior superior and the upper pole of the patella of the participants' dominant and non-dominant extremities will be measured, and the distal 1/3 will be marked. The measurement will be taken in a seated upright position. Care will be taken to avoid compression during the measurement. After ensuring there is no compression in the subcutaneous fat tissue and muscle, an axial image will be recorded. The thickness of the subcutaneous fat tissue, vastus intermedius, rectus femoris, and total quadriceps will be measured three times, and the average of these measurements will be recorded.