How Medical History and Physical Exam Help to Diagnose Psoriatic Arthritis
The diagnosis of psoriatic arthritis begins with a patient’s medical history and a physical exam.
What is asked during the medical history?
During the history, the physician or nurse will ask about a patient’s personal health experiences, such as psoriasis, as well as family health conditions. People with psoriasis are at an increased risk of developing psoriatic arthritis. Psoriatic arthritis also has a high rate of occurrence in families, with the prevalence among first-degree relatives at a rate that is 49 times higher than in the general population.1 Both the patient history of psoriasis and family history of psoriasis are criteria that are considered in the Classification Criteria for Psoriatic Arthritis (CASPAR) criteria, which are commonly used in research and clinical practice to diagnose psoriatic arthritis.2
What happens during the physical exam?
During a physical exam, a doctor examines the patient’s body for signs of disease. The doctor’s exam will include a visual inspection (looking), palpation (feeling), ascultation (listening, often with a stethoscope), and percussion (producing sounds through tapping).3 For diagnosing psoriatic arthritis, physicians rely on both visual inspection and palpation.
Assessing the joints affected by psoriatic arthritis
One of the critical steps during the diagnosis of psoriatic arthritis is the joint assessment, which is completed during a physical examination. Both the number of joints affected as well as the amount of swelling and tenderness of each joint are considered in a joint assessment. Joints are palpated to determine if they are tender and/or swollen. Swelling implies the presence of synovitis, inflammation of the synovial structure between the bones. Joints assessed will include the fingers and toes, the joints between the bones in the hands, the wrist, elbow, shoulder, hip, knee, ankle, the joints in the feet, and the joints around the jaw and sternum.4
The attachment points of the tendons and ligaments (entheses) can also be inflamed due to psoriatic arthritis. This inflammation is known as enthesitis. Classically, enthesitis occurs at the heel (Achilles tendonitis) and the bottom of the foot (plantar fasciitis), but it can involve many parts of the body, including areas around the knee, pelvis, spine, rib cage, shoulder, and elbow. The presence of enthesitis is assessed by palpation to determine the presence or absence of tenderness.4
Several tests may be done to confirm a diagnosis of psoriatic arthritis. In addition to the patient history and physical examination, blood tests are used to rule out other conditions that also cause joint inflammation, such as gout or rheumatoid arthritis. Imaging tests, such as x-ray, ultrasound, MRI (magnetic resonance imaging) and/or CT scan (computed tomography), are often performed to evaluate the joints.2,5