Diagnosis of Rheumatic Diseases
SEPTEMBER 12, 2019
Sergio Schwartzman, MD: How do we diagnose rheumatic diseases? It’s really a panorama depending on the disease state. For example, it’s very easy to diagnose gout. If you aspirate an inflamed joint and you see uric acid crystals in the setting of an inflammatory response with many white blood cells, that diagnosis is completely clear.
However, for other rheumatic diseases there are challenges. We have classification criteria for many of our rheumatic diseases, but we don’t have very many diagnostic criteria. I would address the issue of diagnosis not so much on the basis of the individual components that are important in reaching a diagnosis, but by saying…it is steeped in experience in seeing these diseases, and using some of the parameters that have been outlined in classification criteria that have a completely different intent in the setting of getting a more global picture of the patient.
What elements then are important in helping us make the diagnosis of a rheumatic disease? For me, overwhelmingly the most important element is the history. A very careful and detailed history is very helpful with regard to making the diagnosis. When I was in medical school, we were told that 70% to 90% of your diagnosis should come from the history alone.
The history is a critical element. The physical examination, which unfortunately isn’t being done as detailed as it had been done in the past, is the second most important component of helping us with a diagnosis. After that, for laboratory markers, serological markers for example, in rheumatoid arthritis [RA], we know that 80% of patients who have RA will be either rheumatoid factor- or CCP [cyclic citrullinated peptide]-positive. So, laboratory tests are helpful, but they’re not always diagnostic. For example, in this same type of instance, there are people who have positive rheumatoid factors, or CCPs, and don’t have rheumatoid arthritis. I think that you need to use these serological markers in the context of the history and the physical exam that you’ve done.
Imaging has become increasingly important. To that point, I think ultrasound is now becoming a tool frequently used by the rheumatologist to define inflammatory disease and to address the mechanical disease that’s not necessarily autoimmune. I think that the analogy of the ultrasound being the equivalent for the rheumatologist as the stethoscope is for the cardiologist has been raised, and for some rheumatologists, that’s correct. I believe that MRI [magnetic resonance imaging] has clearly changed the capacity to diagnose axial spondyloarthritis. It’s in fact 1 of the necessary components for the classification of axial spondyloarthritis. There’s a clinical arm where you have an HLA-B27, and then at least 2 features of spondyloarthritis, or an imaging arm, which is the MRI, or x-ray if that’s positive. But frequently, the MRI will be positive before the x-ray is and only 1 component of spondyloarthritis.
In summary, the diagnosis of a rheumatic disease is heavily dependent on a very good history, a very good physical, and supported by both laboratory studies and imaging studies. As we move into the next quantum change in understanding rheumatic diseases, I believe that our diagnostic tools will improve. I think that genomics will change that. I think that serologies will become much more sensitive, and even more important, much more specific as well.
Rheumatic illnesses are not static. They evolve and change over time. In the early phases of any of the rheumatic diseases, they will not present classically the way that they’re described in textbooks. Patients who have rheumatoid arthritis early on will present with a little bit of morning stiffness and arthralgias. The history will be significant for inflammatory type symptoms, but the exam may not yield very much. As diseases evolve over time, that same patient that on exam you don’t see anything, you’re going to see red hot swollen joints 1 year later when they come back. Early detection of rheumatic diseases can be challenging based on inconclusive history, a physical exam that is not diagnostic, and frequently the best diagnostician is time, and giving a disease time to evolve.
The challenge in that circumstance though is that the reason that we want to make an early diagnosis of a rheumatic disease is that we believe that intervening, and intervening aggressively early, is a critical element in preventing some of the permanent damage that some of these rheumatic diseases cause. For example, in rheumatoid arthritis, once you develop an erosion, there’s nothing that I can do to wipe away that erosion. We know that erosions are associated with quality of life, and disability. Making an early diagnosis can be challenging based on the clinical spectrum, but it is important to do. Sometimes we’re not sure of the diagnosis, and I think that probably happens in rheumatic diseases more frequently than it does in other subspecialties.
Transcript edited for clarity.