Painful inconsistency in fibromyalgia diagnoses

Uncertainty continues around fibromyalgia diagnoses with evidence of a lack of agreement between clinical diagnoses and those made on the basis of fibromyalgia criteria.

A US-based study of almost 500 rheumatology patients found about 21% had a clinical diagnosis of fibromyalgia and about 24% of patients satisfied the 2011 American College of Rheumatology criteria for fibromyalgia.

However the researchers said agreement between the two groups was ‘only fair’.

“Physicians failed to identify 60 criteria-positive patients (49.6%) and incorrectly identified 43 criteria-negative patients (11.4%),” they wrote in Arthritis Care & Research.

“Among the 104 patients clinically diagnosed with fibromyalgia, only 61 (58.7%) actually satisfied criteria, and among the 393 not diagnosed with fibromyalgia by clinicians, 60 (15.3%) satisfied the 2011 criteria.”

“Because the number of individuals without fibromyalgia in the community is much greater than the number of those with fibromyalgia, a misclassification rate of 15.3% is clinically and epidemiologically meaningful.”

Gender of the patients and different emphasis given to different symptom scores were identified as some of the possible reasons for misclassification of patients.

For example, women comprised about 98% of patients diagnosed clinically and only 83% of criteria-positive women.

And patients with the highest symptom severity scores but lowest widespread pain index (WPI) and polysymptomatic distress (PSD) were more likely to have a clinical diagnosis of fibromyalgia.

“Thus, clinicians gave greater weight in making a diagnosis to being a women and having increased symptoms and were willing to diagnose patients with lower WPI and PSD scores.”

“In addition, a number of significant contextual factors were not formally assessed in this study but may have been important to clinicians and influenced diagnosis, including a history or family history of fibromyalgia, and co-morbid conditions such as irritable bowel syndrome and restless leg syndrome.”

“Other important reasons for discordance include not accepting the fibromyalgia concept, not considering fibromyalgia, or not needing a fibromyalgia diagnosis for patient care.”

The study warned that clinical misdiagnosis posed the risk of inappropriate treatment of patients.

However an accompanying editorial said classification criteria could never replace clinical acumen.

“Only the health care provider can perform the physical examination and interpret psychosocial factors and co-morbid illness that clarify a diagnosis,” it said.

“Rheumatologists are best able to strategize subsets of fibromyalgia patients and assist in individualized management, particularly in the most challenging scenarios.”

“We are the go-to experts for patients and our colleagues for the diagnosis of fibromyalgia, whether or not we readily accept that role.”

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