From the Guidelines
The diagnostic criteria for fibromyalgia involve widespread pain lasting at least three months, defined as pain in at least four of five regions of the body, along with significant levels of other symptoms including fatigue, waking unrefreshed, and cognitive problems, as outlined in the most recent guidelines 1. To diagnose fibromyalgia, clinicians typically look for:
- Widespread pain lasting at least three months
- Pain in at least four of five regions of the body (left upper, right upper, left lower, right lower, and axial)
- Significant levels of other symptoms including:
- Fatigue
- Waking unrefreshed
- Cognitive problems Some diagnostic approaches use the:
- Widespread Pain Index (WPI) and Symptom Severity Scale (SSS)
- WPI score of at least 7 and SSS score of at least 5, or alternatively a WPI of 4-6 with SSS of at least 9 Importantly, other conditions that might explain the symptoms must be ruled out through appropriate testing, which may include:
- Blood tests to check for rheumatoid arthritis, lupus, thyroid disorders, and other inflammatory conditions
- Laboratory and radiological exams if needed to exclude treatable comorbidities 1
- Referral to other specialists if necessary Diagnosis should be made by a healthcare provider experienced in evaluating chronic pain conditions, usually a rheumatologist, as fibromyalgia symptoms overlap with many other disorders. The American College of Rheumatology (ACR) classification criteria for FMS are the most commonly used in clinical and therapeutic research, as noted in earlier studies 1. However, the most recent guidelines from 2017 provide the most up-to-date recommendations for diagnosis and management 1.
From the Research
Diagnostic Criteria for Fibromyalgia
The diagnostic criteria for Fibromyalgia, also known as Fibromyalgia Syndrome, have undergone changes over the years. The American College of Rheumatology (ACR) published diagnostic research criteria for fibromyalgia in 1990, which included:
- A history of chronic and widespread pain
- The presence of 11 or more out of 18 tender points
- Pain considered chronic widespread when all of the following are present: pain in the left side of the body, pain in the right side of the body, pain above the waist, pain below the waist, and axial skeletal pain
- The duration of pain must be more than 3 months 2
Revised Diagnostic Criteria
However, in 2010, a new case definition of fibromyalgia was recommended, which includes:
- A widespread pain index (WPI) of 7 or more
- A symptom severity (SS) scale of 5 or more
- Alternatively, a WPI of 3-6 and an SS scale of 9 or more 3 This new definition does not require a tender point examination and is considered more practical for clinical diagnosis.
Comparison of Diagnostic Criteria
Studies have compared the 1990 and 2010 ACR diagnostic criteria for fibromyalgia, finding that the 2010 criteria are more sensitive and easier to use 4. The 2010 criteria also enable assessment of fibromyalgia symptom severity and can be used for longitudinal evaluation of patients with marked symptom variability 3.
Key Diagnostic Variables
The most important diagnostic variables for fibromyalgia include:
- Widespread pain index (WPI)
- Categorical scales for cognitive symptoms, unrefreshed sleep, fatigue, and number of somatic symptoms
- Symptom severity (SS) scale 2, 3
Screening and Diagnosis
Fibromyalgia can be diagnosed using the American College of Rheumatology criteria or the Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Networks-American Pain Society Pain Taxonomy diagnostic criteria 5. The Fibromyalgia Rapid Screening Tool is a helpful screening method for patients with diffuse chronic pain 5.