Physician-based and patient-based reporting of fibromyalgia symptoms yielded similar rates of fibromyalgia diagnosis in an analysis of rheumatology patient cases reported to the National Data Bank for Rheumatic Diseases.
The analysis provides evidence that the 2010 American College of Rheumatology diagnostic criteria and the 2011 modified version give consistent results, which has been a concern of researchers and clinicians because the 2010 criteria use only physician-based assessment of patient-reported symptoms, whereas the 2011 modified criteria use only questionnaire data from patient self-reports of symptoms.
Dr. Brian Walitt
The clinical importance of the study is that it reminds clinicians that “for the most part, patients and physicians agree in their assessment of symptoms,” study coauthor Dr. Brian Walitt said in an interview. It also shows, he noted, that “the scores and criteria used in physicians’ offices or in pharmacological research where patients are being evaluated and scored likely represent the same phenomenon that we would see in an epidemiological study.”
Although the findings indicate that the 2010 and 2011 criteria give acceptable agreement between fibromyalgia diagnosis and scores on the polysymptomatic distress scale (PSD) for research purposes, they don’t sufficiently agree for clinical decision making and diagnosis, so physicians and patients together must judge the best course of action, the researchers said (Arthritis Care Res. 2015 Sep 28. doi: 10.1002/acr.22742).
The researchers used a data set from the National Data Bank for Rheumatic Diseases in which they randomly selected 30 participating rheumatologists who contributed 514 rheumatology patients: 281 with a diagnosis of fibromyalgia prior to the study assessment and 233 control subjects with previously diagnosed noninflammatory painful disorders. The study incorporated all the physician-based variables involved in the 2010 criteria, including the Widespread Pain Index (WPI), widespread pain, the Symptom Severity scales (SS), the Polysymptomatic Distress scale (PSD), and fibromyalgia diagnosis, and patients separately completed the same study variables on their own.
A fibromyalgia diagnosis can be made in both the 2010 and 2011 criteria when the WPI is 7 or greater and the SS is 5 or greater, or when the WPI is 3-6 and the SS is 9 or greater. The creation of the PSD in the 2011 criteria by adding the scores on the WPI and SS (yielding a range of 0-31) defined a fibromyalgia diagnosis as a score 12 or higher. The PSD scale also allows measurement of “how close the patient is to satisfying the criteria, how much above the criteria cut point the patient’s severity is and, in this comparative study, the degree of agreement in physician and patient assessments,” the authors wrote.
In the 514 patients, patient-based criteria led to 225 diagnoses of fibromyalgia, compared with 215 diagnoses with physician-based criteria. There were 84 patients with discordant results for fibromyalgia diagnosis, including 56% who were positive by patient but not by physician measures and 44% who were positive by physician but not by patient measures. The overall diagnostic agreement in all patients was 84%, which had a kappa statistic for agreement beyond chance of 0.67, which is considered to indicate substantial agreement.
The mean PSD score was virtually the same using physician measures (12.3) or patient measures (12.8), but the level of agreement between physician and patient PSD scores dropped as the cut point for fibromyalgia diagnosis (PSD score of 12) approached.
About 85% of the physician and patient PSD scores differed by less than 5 units, but 15% were outliers where the patient and physician assessments were widely discordant. “They’re not really common, but it reminds us that it happens, too, and that’s something that’s interesting to understand on its own,” said Dr. Walitt, director of clinical pain research at the National Center for Complementary and Integrative Health and medical officer at the National Institute of Nursing Research.
“Where the discordance comes from is really right at the cut point. And so if you use the cut point religiously, you’ll have a problem because some people who are right at that margin will be classified one way or the other when the truth is that they’re all moderately symptomatic. In some ways, fibromyalgia is a measure of symptom severity. To have fibromyalgia means not just to have symptoms but those symptoms have to be severe enough to be recognized as fibromyalgia. Not everybody with aches and pains qualifies, so if you’re right around the cut point, it’s a good thing to talk to the patient to get a feel for them and understand their narrative in order to make the diagnosis regardless of which side of the cut point they’re on,” he said.