Cognitive biases: after all, how can we diagnose fibromyalgia?

In this Purple February, an expert addresses the cognitive biases of the diagnosis that can lead to error

According to Dr. Felipe Mendonça, rheumatologist at Imuno Brasil, fibromyalgia is a central sensitization syndrome that presents chronic widespread pain. And, in this awareness month of Purple February, it is necessary to address cognitive biases and diagnostic methodologies in order to avoid mistakes.

As there is no pathognomonic test capable of diagnosing fibromyalgia, the diagnosis is usually made, in clinical practice, through findings and subjective experiences of the professional, which is referred to in the medical literature as clinical fibromyalgia (ClinFM). However, this method reveals discrepancies in the results, since the diagnosis can vary considerably between physicians.

Given this context, the question is: is there a correct way to diagnose fibromyalgia? The expert and author of the article “Cognitive biases in fibromyalgia diagnosis”, published in the scientific journal Joint Bone Spine (p. 105339-105339, 2022), talks about the criteria-based method, also known as Fibromyalgia Status by Criteria (CritFM), which underlies studies in the area.

This form of diagnosis is based on criteria validated by clinical research, through a score of the patient’s signs and symptoms, that is, how they see and feel what is happening to their own body. This step is performed based on a questionnaire. Although this method is essential for the homogenization of patients for research purposes, it frequently leads to false positives and negatives in clinical practice.

Despite the importance of the patient’s opinion, which can be quantified through diagnostic criteria, medical evaluation is essential to conclude any result, mainly to exclude the possibility of autoimmune rheumatic diseases. This happens because many other diseases can present with a similar picture, often fulfilling all CritFM criteria.

And for this to happen correctly, professionals must also consider the cognitive biases of the diagnosis of fibromyalgia, that is, the errors and erroneous tendencies of reasoning, which are inherent to human beings, and which can lead the physician to a wrong diagnostic, as Dr. Felipe specifies below.

– Representation bias: pre-formed stereotypes of fibromyalgia patients, often with characteristics that are not actually part of the disease, which lead the physician to erroneously diagnose as fibromyalgia patients who fit this pre-formed stereotype.

– Confirmation bias: once a pre-formed diagnostic opinion has been prepared for a given patient, the physician tends to ignore new information that suggests a diagnosis other than the one initially made. Thus, patients initially diagnosed with fibromyalgia continue to be classified as having fibromyalgia, even when information appears that speak against the diagnosis, which deserves to be reviewed.

– Survey satisfaction bias: refers to the tendency not to explore more tests or symptoms, once fibromyalgia has been identified as a diagnosis, which may leave aside new diagnostic assessments that could change the course of reasoning and treatment. 

– Momentum bias: failure to continuously review a diagnosis can lead to error, as some symptoms may disappear and others may be discovered, completely changing the result. This bias represents a “diagnostic inertia” in which there is a resistance for a diagnosis to be continually reviewed as to its pertinence.

The alert in this important month for fibromyalgia is for physicians and patients to be attentive to the constancy of the differential diagnoses of Fibromyalgia and, thus, not to fall into the trap of cognitive biases.

About the Doctor: Dr. Felipe Mendonça de Santana, director of operations at Imuno Brasil and rheumatologist from the Faculty of Medicine of the University of São Paulo (FMUSP).