In a recent study published in the journal PLos ONE, a team of researchers reports the development of specific surrogate criteria that allows for the study of fibromyalgia and polysymptomatic distress in the US National Health Interview Survey.

Fibromyalgia is a medical diagnosis used to describe the diminished quality of life related to generalized body pains and physical and psychological symptoms that occurs in the absence of a clear pathologic cause. To be diagnosed with fibromyalgia the symptomatic patient needs to seek health care from clinicians that then need to interpret the described symptoms as such.

The development of the 2011 modification for survey research of the American College of Rheumatology (ACR) Preliminary Diagnostic Criteria for Fibromyalgia has enabled investigators to approximate both fibromyalgia diagnosis and severity outside of the clinical setting. The modified 2011 criteria, can be used to determine a “calculated prevalence” of fibromyalgia in a given population.

In the study entitled “The Prevalence and Characteristics of Fibromyalgia in the 2012 National Health Interview Survey”, Brian Walitt from the National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda in Maryland and colleagues developed and tested surrogate criteria for fibromyalgia in rheumatology practices using variables from the US National Health Interview Survey (NHIS) and the modification (for surveys) of the 2010 American College of Rheumatology (ACR) preliminary fibromyalgia criteria. The researchers applied the surrogate criteria to the 2012 NHIS and identified subjects who had the necessary criteria from symptom data. The NHIS weighted samples of 8,446 persons represented 225.7 million American adults.

Based on existing symptoms’ severity standards for determining fibromyalgia, the researchers found an approximate pathology prevalence of 1.75%. However, the team also detected that fibromyalgia symptoms, as measured by the polysymptomatic distress scale, were continuous and that there was no clearly defined cut-point that separated fibromyalgia from non-fibromyalgia.

Results also shown that those with a diagnosis of fibromyalgia had high levels of self-reported pain, comorbidity, non-pain symptoms and psychological distress; Moreover the results revealed that these people had substantial medical costs and high rates of Social Security disability and work disability. A diagnosis of fibromyalgia was associated with gender, ethnicity, citizenship, education and unhealthy behaviors.

According to the researchers, although the direction of causality is often unclear in cross-sectional data, physical illness comorbidities observed in the study suggest that the related stress lies on the causal pathway to fibromyalgia development. Furthermore, psychological status may also play a role, as other research points to some degree of causality.

Finally, the “under diagnosis” of clinical fibromyalgia and the relation of demographic factors to diagnosis points toward the possible influence of social and cultural factors on diagnosis acceptability. As the authors conclude in their study ” we have developed study specific surrogate criteria that allowed us to study fibromyalgia and polysymptomatic distress in the US National Health Interview Survey, the principal source of information on the health of the civilian noninstitutionalized household population of the United States.”