E2 ModerateModerate confidencePEM not requiredCross-SectionalPeer-reviewedReviewed
Standard · 3 min
Performance of the American College of Rheumatology 2016 criteria for fibromyalgia in a referral care setting.
Ahmed, Sakir, Aggarwal, Amita, Lawrence, Able · Rheumatology international · 2019 · DOI
Quick Summary
This study tested how well the 2016 fibromyalgia diagnostic criteria work in hospital specialty clinics, where patients often have multiple conditions. Researchers found that the newer criteria identified some patients that an experienced doctor using older criteria would not have diagnosed, and these patients were more likely to also have other conditions like restless leg syndrome, PTSD, or chronic fatigue syndrome. The 2016 criteria performed reasonably well, but doctors should be aware they may be catching patients with overlapping conditions rather than pure fibromyalgia.
Why It Matters
Since ME/CFS frequently co-occurs with fibromyalgia and both are classified as central sensitization syndromes, understanding how fibromyalgia diagnostic criteria perform in complex patient populations is crucial. This study demonstrates that the 2016 criteria may capture a broader, more comorbid phenotype, which has implications for ME/CFS patient populations who often meet multiple overlapping syndrome criteria. The findings help clinicians in tertiary settings recognize when patients diagnosed with fibromyalgia may actually represent complex presentations requiring evaluation for concurrent ME/CFS and other conditions.
Observed Findings
Of 147 patients, 112 met ACR 1990 criteria and 93 met ACR 2016 criteria, with disagreement in 47 patients.
ACR 2016 sensitivity was 71% and specificity was 60% against the ACR 1990 reference standard.
Patients meeting only ACR 2016 criteria had significantly higher GAD-7 (anxiety) scores compared to those meeting only ACR 1990 criteria.
Patients diagnosed by ACR 2016 criteria had 5.2-fold higher odds of having concurrent restless leg syndrome, PTSD, or chronic fatigue syndrome.
Depression (BPHQ) and alexithymia (TAS-20) scores did not differ significantly between the diagnostic criterion groups.
Inferred Conclusions
The ACR 2016 criteria are valid for fibromyalgia diagnosis in tertiary care settings, showing comparable performance to primary care-based validation studies.
Patients identified solely by ACR 2016 criteria (not by ACR 1990) represent a phenotype enriched for anxiety and other central sensitization comorbidities.
The ACR 2016 criteria may capture a broader, more comorbid patient population than the ACR 1990 criteria, particularly in referral settings with higher baseline comorbidity.
Remaining Questions
Does the higher comorbidity rate in ACR 2016-only patients reflect superior case-finding or diagnostic misclassification in a more complex population?
What This Study Does Not Prove
This study does not establish causation or explain why the ACR 2016 criteria identify patients with more comorbidities—only that an association exists. The cross-sectional design cannot determine whether anxiety and other conditions influence fibromyalgia diagnosis or vice versa. The study uses ACR 1990 criteria as reference standard, which itself is not perfect, so any disagreement with ACR 2016 may reflect limitations in both criteria rather than true diagnostic accuracy.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
Contribute
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How do ME/CFS patients specifically perform against both ACR criteria sets, and what is the overlap between fibromyalgia and ME/CFS diagnosis in this cohort?
Which specific clinical or laboratory features best distinguish fibromyalgia from overlapping conditions like ME/CFS in tertiary settings?
Do the different diagnostic criteria predict different treatment responses or long-term outcomes?