Fibromyalgia Diagnostic Criteria
The American College of Rheumatology 2016 revised criteria are the current standard for diagnosing fibromyalgia in adults, requiring generalized widespread pain for ≥3 months combined with a Widespread Pain Index (WPI) ≥7 plus Symptom Severity Scale (SS) ≥5, OR WPI 3-6 plus SS ≥9, along with a generalized pain criterion to prevent misclassification of regional pain syndromes. 1
Core Diagnostic Requirements
A patient meets diagnostic criteria when ALL of the following are present:
- Generalized pain in at least 4 of 5 body regions (not just widespread pain in multiple quadrants), which eliminates misclassification of regional pain disorders 1
- Symptom duration ≥3 months of continuous pain 2, 3, 1
- WPI score ≥7 AND SS scale score ≥5, OR alternatively WPI 3-6 AND SS scale ≥9 1, 4
The 2016 revision specifically corrected a major flaw in earlier versions by adding the "generalized pain criterion" that requires pain in at least 4 of 5 body regions, which prevents regional pain syndromes from being misclassified as fibromyalgia 1.
Widespread Pain Index (WPI) Calculation
- Count the number of painful body areas from a list of 19 possible regions over the past week 1, 4
- The 19 regions include: left and right shoulder girdle, upper arm, lower arm, hip, upper leg, lower leg, jaw, chest, abdomen, upper back, lower back, neck, and one additional region 4
- Score ranges from 0-19 based on number of painful areas 4
Symptom Severity (SS) Scale Calculation
Sum the severity scores (0-3 scale) for three core symptoms, then add the somatic symptom score:
- Fatigue severity (0=no problem, 3=severe) 1, 4
- Waking unrefreshed (0=no problem, 3=severe) 1, 4
- Cognitive symptoms (0=no problem, 3=severe) 1, 4
- Plus general somatic symptoms score: 0 points for no symptoms, 1 point for few symptoms, 2 points for moderate number, 3 points for great deal of symptoms 1, 4
Total SS scale ranges from 0-12 1, 4
Associated Clinical Features (Not Required for Diagnosis)
While not part of the formal criteria, these symptoms strengthen clinical suspicion:
- Hyperalgesia and allodynia with reduced pain threshold 2, 3
- Mood disturbances including anxiety and depression 3
- Headache, migraine, irritable bowel symptoms, urinary frequency 2
- Disproportionate fatigue relative to activity level 3
Critical Diagnostic Pitfalls to Avoid
The 1990 ACR tender point criteria (11 of 18 tender points) are outdated and should NOT be used as the primary diagnostic method, though they remain valid for classification purposes in research 1, 4. The tender point examination has significant limitations in clinical practice and was abandoned in favor of symptom-based criteria 5, 6.
Do not diagnose fibromyalgia in patients with only regional pain syndromes—the generalized pain criterion requiring pain in at least 4 of 5 body regions specifically prevents this misclassification error 1.
Laboratory testing is used to exclude mimicking conditions, not to confirm fibromyalgia, as there are no specific diagnostic tests for fibromyalgia itself 3, 5. Basic screening should include ESR, CRP, thyroid function, creatine kinase, and vitamin D to rule out inflammatory, endocrine, or muscle diseases 3.
Validation and Performance
The 2016 criteria demonstrate median sensitivity of 86% and specificity of 90% when compared against clinical diagnosis and 1990 classification criteria 1. The criteria correctly classify approximately 88% of cases and eliminate the previously confusing recommendations regarding diagnostic exclusions 1, 4.
The physician-based criteria are valid for individual patient diagnosis in clinical practice, while the self-report version is valid only for research studies, not for clinical diagnosis of individual patients 1.