A recent paper illustrates how using different fibromyalgia criteria affects reports of its prevalence.1
Writing in Arthritis Care & Research, researchers found the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks–American Pain Society Pain Taxonomy (AAPT) criteria caused far more people to be categorized as having fibromyalgia than criteria put forth by the 2016 revisions to the 2010/2011 fibromyalgia diagnostic criteria in a randomly selected German population to whom researchers applied both sets of criteria.1-3 Using the AAPT criteria, Häuser et al. found the prevalence of fibromyalgia was 73% greater than with the modified 2016 criteria. Individuals diagnosed according to the AAPT criteria also had fewer pain sites and less severe symptoms, the researchers say.1
“The criteria overlap, but they don’t agree well,” says senior author Frederick Wolfe, MD, director of the National Databank for Rheumatic Diseases, Wichita, Kan. “The two sets of criteria identified two sets of patients. The criteria do not solve the question of who has fibromyalgia.”
Dr. Wolfe, who was named an ACR Master in 2001, led the development of the 1990 and 2010 ACR fibromyalgia criteria, and subsequent modifications.
A Short History
Criteria for fibromyalgia have changed over the years. The 1990 ACR classification criteria required the presence of widespread pain and specialized physical examinations to quantify tender points. Not many providers had training to perform the exams.
The subsequent 2010 ACR diagnostic criteria allowed providers to base a diagnosis of fibromyalgia on the patient’s history. The 2010 diagnostic criteria required assessment of the extent of fatigue, unrefreshed sleep and cognitive dysfunction or remembering, along with the somatic symptom burden. The 2010 ACR criteria involved asking patients about pain or tenderness in 19 body regions, with a resultant score on a widespread pain index (WPI). Physicians also asked patients about fatigue, cognitive function, poor sleep, and a wide array of other symptoms for scoring on a symptom severity scale (SSS).
A diagnosis of fibromyalgia under the 2010 criteria required the patient: 1) have a WPI score of 7 or higher and an SSS score of 5 or higher, or a WPI score of 3–6 and an SSS score of 9 or higher; 2) experience symptoms at a similar level for at least three months; and 3) have no other disorder that would otherwise fully explain their pain.4
A 2011 update to the 2010 ACR criteria replaced the long list of elements a clinician had to assess with a questionnaire asking patients about depression, irritable bowel syndrome symptoms and headache. Adding scores from the WPI and SSS yielded an index of 0–31, called the polysymptomatic distress scale (PDS).4 The PDS is a measure of overall symptom severity, Dr. Wolfe explains.
The scale’s name is controversial. Some physicians—including Daniel Clauw, MD, professor of anesthesiology, rheumatology and psychiatry at the University of Michigan Medical School, Ann Arbor, and the author of an editorial published alongside the Häuser et al. study—maintain the PDS does not measure patient distress.
The 2016 modification of the 2010/2011 criteria does not exclude the presence of other pain conditions.
The modification raised the WPI minimum score from 3 to 4 and added a requirement that the pain be generalized.3 The 2016 modification retains the SSS from the earlier version of the criteria, adding it to the WPI to form what is now called the fibromyalgia severity scale or polysymptomatic distress scale (FSS/PDS). The FSS/PDS can be used as a continuous scale or for diagnostic purposes using the specified thresholds.
AAPT criteria were issued as a diagnostic system intended to be clinically useful and consistent across various chronic pain disorders—including fibromyalgia. The system includes not only core or required dimensions that can be used for diagnosis, but also supportive signs and symptoms that can help clinicians increase their confidence in the diagnosis.
The AAPT diagnostic cutoff for fibromyalgia is based on the presence of pain in at least six of nine pain sites and moderate to severe sleep problems or fatigue for at least three months. AAPT pain regions include the head, chest and abdomen, which are not scored in the 2016 modification.2,5