A 55-year male-old with PMHx of hand surgery, hypothyroidism, COPD, asthma, OSA, pre-DM, CAD with LCX stent, shoulder surgery, and chronic pain presents to the clinic with a chief complaint of chronic hand swelling.
His physician is tempted to diagnose early rheumatoid arthritis. Some risk factors are there: heavy smoker, family history of RA, and prior autoimmune disease. Parts of the description match up: painful/swollen hands and fingers, morning stiffness, symmetric joint involvement, decreased physical functioning, and QoL.
It passes the Squeeze Test: pain is elicited at the MCP joints when the physician grips the patient’s hand, above the wrist and below the proximal knuckles. (This is a casual clinical test and has low specificity).
There is only one problem. It fails the Pulp Test (not an actual test). In other words, all pertinent labs are negative. ESR is 2. CRP is 3. Anti-citrullinated protein antibody is within the reference range.
Well, two problems. Imaging also discourages the diagnosis of RA. From a December 2020 X-Ray: Bone mineralization is normal. There is no fracture or dislocation. Joint spaces are maintained overall. Carpal alignment and interspacing are maintained. Mild osteoarthritic changes of the first IP joint noted bilaterally, right worse than left. IMPRESSION: No acute abnormality.
This patient is suffering from some form of arthritis. But we wanted to know if it is possible to diagnose Rheumatoid Arthritis without relying on labs. Yes, it is. Barely. You must have many joints affected to make up for negative serology.
According to a 2018 JAMA paper, Diagnosis and Management of Rheumatoid Arthritis, no diagnostic criteria exist for RA. There is, however, a quick table of classification criteria joint-authored by the American College of rheumatology and the European Union League Against Rheumatism. Another paper, Annals of Internal Medicine: Rheumatoid Arthritis (2019), provided a more detailed explanation of this table. Please see the attachment. I have highlighted and underlined select pages and sections that are most vital for making a diagnosis in this patient.
The table uses the following categories to diagnose RA: 1) joint involvement and distribution 2) serology 3) acute phase reactants 4) duration of symptoms. Our patient scored six out of 10. Six is the minimum score to pass for “definite RA.” He earned most of those points from the joint involvement category. Interestingly, joint involvement nets up to five points; serology and acute phase reactants combine for only four. Duration of symptoms accounts for the last point.
Given the importance of assessing the small joints one by one, next time I would perform the squeeze test five times per hand, each time asking about the middle joint, thumb joint, etc. That would enable me to count the number of joints affected, rather than making assumptions about the entire hand. I gave the patient the highest score in this department, but that was an estimation.
It turns out the labs and imaging are not as important as I initially thought. 30% of patients with RA have normal labs. Synovial fluid analysis is not required to make a diagnosis. Radiographic findings are not required to make a diagnosis.
We are still not sure if our patient has RA, as there are several disease processes that can cause hand pain and swelling. He has been referred to a rheumatologist.
Benjamin Samuel Young 