What are the criteria to suspect fibromyalgia (Fibromyalgia Syndrome) in a patient?

How to Suspect Fibromyalgia

Suspect fibromyalgia when a patient presents with chronic widespread pain lasting at least 3 months, accompanied by fatigue, sleep disturbances, and cognitive dysfunction, particularly in women aged 30-60 years. 1, 2

Core Clinical Features to Identify

Primary Symptom: Widespread Pain

• Chronic pain present in all four body quadrants (upper and lower, left and right) for a minimum of 3 months 1, 3
• Pain characterized by hyperalgesia (increased pain response) and allodynia (pain from normally non-painful stimuli) 1
• Pain intensity can be assessed using the Visual Analogue Scale (VAS) 4, 5

Associated Symptoms That Strengthen Suspicion

• Fatigue that is disproportionate to activity level 1, 2
• Non-restorative sleep or sleep disturbances 1, 6
• Cognitive dysfunction (often described as "fibro fog") 2, 6
• Mood disturbances including anxiety and depression 1, 3
• Headaches or migraines 1
• Irritable bowel symptoms, variable bowel habits, or diffuse abdominal pain 1
• Urinary frequency 1

Demographic and Clinical Context

High-Risk Populations

• Women are disproportionately affected compared to men 2, 6
• Prevalence of approximately 2% in the general population 1, 2
• Prevalence increases with age 6

Triggering Events to Inquire About

• History of physical trauma preceding symptom onset 7
• History of emotional trauma or significant stressors 7
• Note: Many patients will have no identifiable trigger 7

Physical Examination Findings

Tender Point Assessment (Historical Approach)

• Digital pressure at 11 out of 18 specific tender points produces pain 7
• However, clinicians should be aware of limitations in using tender points for diagnosis, as the ACR 1990 criteria were designed for classification, not individual diagnosis 3

Key Examination Caveat

• No objective inflammatory signs (no joint swelling, warmth, or erythema) 3, 6
• No organic damage on examination 7

Screening Approach

Initial Screening Tool

• Use the Fibromyalgia Rapid Screening Tool for patients presenting with diffuse chronic pain 2
• This provides a systematic first approach before applying formal diagnostic criteria 3

Formal Diagnostic Criteria Application

• American College of Rheumatology (ACR) criteria are the most commonly used in clinical practice 1, 4, 5
• The ACR criteria focus on widespread pain and associated symptoms rather than laboratory or imaging findings 4
• Alternative: AAPT (Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Networks-American Pain Society Pain Taxonomy) diagnostic criteria 2

Essential Differential Diagnosis Considerations

Rule Out Inflammatory and Endocrine Diseases

Obtain basic laboratory screening to exclude alternative diagnoses:

• Erythrocyte sedimentation rate (ESR) 4, 5
• C-reactive protein (CRP) 4, 5
• Thyroid function tests 4, 5
• Creatine kinase (to rule out myopathy) 4, 5
• Vitamin D levels 4, 5

Overlapping Conditions to Consider

• Chronic fatigue syndrome may coexist or present similarly 1, 3
• Irritable bowel syndrome 3
• Migraine 1
• Rheumatologic conditions (systemic lupus, rheumatoid arthritis) must be excluded 3, 2
• Post-Lyme disease syndrome can present with multiple tender points and widespread pain, fulfilling fibromyalgia criteria 1

Psychiatric Comorbidities

• Higher prevalence of psychiatric disorders in fibromyalgia patients 3
• Take a careful history for primary mood disturbances (depression, anxiety disorders) 3
• Distinguish between fibromyalgia-associated mood symptoms and primary psychiatric conditions 3

Functional Impact Assessment

Quantifying Disease Burden

• Use the Fibromyalgia Impact Questionnaire (FIQ) to measure functional impairment and impact on daily activities 4, 5
• Assess pain, fatigue, sleep quality, and daily functioning as key outcome domains 1

Psychosocial Context

• Evaluate psychosocial aspects comprehensively, as fibromyalgia significantly impacts quality of life 4, 5
• Assess the patient's ability to cope with stress and their biopsychological resilience 6

Common Diagnostic Pitfalls to Avoid

• Do not use fibromyalgia as a diagnosis of exclusion—it is a positive clinical diagnosis based on characteristic features 8
• Avoid over-reliance on tender point examination alone, as this has limitations and the criteria have evolved 3
• Do not assume normal laboratory tests rule out fibromyalgia—there are no specific laboratory abnormalities for this condition 3, 8
• Recognize that diagnosis often takes over 2 years with an average of 3.7 consultations with different physicians, leading to high healthcare utilization 1
• Be aware that establishing the diagnosis early can reassure patients and decrease unnecessary testing 2