The impact of changes in fibromyalgia diagnosis criteria: using NAMCS data (2010-2019) to identify trends

Fibromyalgia is currently diagnosed under the 2016 research criteria, a combination of the 2010 and 2011 criteria revisions. The current guidelines have led to ongoing misdiagnosis issues dating back to the criteria initially established by the 1990 American College of Rheumatology (ACR). Given the extensive revisions to the diagnostic criteria in 2016, instances of over-and under-diagnosing as well as measurement errors corresponding to the different diagnostic criteria utilized, the current study sought to investigate changes in the incidence of fibromyalgia diagnoses and the associations between fibromyalgia diagnosis and relevant comorbidities and somatic symptoms of interest.

This retrospective, observational, cross-sectional study of adults (18 + years of age) used the most recently available National Ambulatory Medical Care Survey (NAMCS) datasets from 2010 to 2019. A plot of annual point estimates of the proportion of visits where fibromyalgia was diagnosed (and associated 95% confidence intervals) was generated. In addition, a multivariable logistic regression model was constructed to assess the relationship of covariates available in the NAMCS on the outcome of fibromyalgia diagnosis (yes/no).

Since the implementation of the 2010 ACR criteria, the percentage of visits resulting in a fibromyalgia diagnosis increased prior to the release of the 2016 criteria, after which a general downward trend was observed. Both rheumatoid arthritis (OR 5.51, 95% CI 2.87-10.58) and depression (OR 2.61, 95% CI 1.90-3.58) were found to be strongly associated with a fibromyalgia diagnosis. Other comorbid conditions showed minimal associations.

Based on the fluctuation in the proportion of NAMCS visits resulting in a fibromyalgia diagnosis post-implementation of the 2016 criteria, the current criteria may not accurately represent the sensitivity to comorbid conditions seen in the 2010 criteria through symptom severity scales. The analysis of comorbidities and somatic symptoms revealed that rheumatoid arthritis and depression continue to be two defining comorbidities in the diagnosis of fibromyalgia; however, diagnostic challenges remain.

Not applicable.