CHICAGO – Fibromyalgia assessment screening tool (FAST) indices derived from the Multidimensional Health Assessment Questionnaire (MDHAQ) provide a simple and effective method for identifying fibromyalgia in routine care, according to findings from a series of more than 500 patients.
Sharon Worcester/MDedge News
Dr. Juan Schmukler
The indices are as accurate as the existing – and more complex – diagnostic criteria for fibromyalgia, Juan Schmukler, MD, reported at the annual meeting of the American College of Rheumatology.
For example, three FAST indices developed in the course of the study had better performance versus existing diagnostic criteria than did certain individual MDHAQ scales alone (area under the curve range, 0.924-0.937 vs. 0.829-0.889, respectively), said Dr. Schmukler, who conducted the research as a medical student at Rush Medical College, Chicago, and is now a rheumatology fellow at Mount Sinai Hospital in Chicago.
The findings are notable, because the two-page MDHAQ and a summary index (the RAPID3) derived from three of the MDHAQ scales are already used routinely in clinical care for diagnosing rheumatic diseases, and the new indices could easily – and with minimal work flow disruption – also be incorporated for each patient at each visit.
“Fibromyalgia is common in the general population and it is believed to be more common in patients with other rheumatic diagnoses,” Dr. Schmukler said. “Fibromyalgia may be easily recognized in many cases, but it can also be very subtle, particularly in patients who have other rheumatic diseases.”
ACR fibromyalgia classification criteria published in 1990 were based on tender point examination and non-ACR diagnostic criteria as revised in 2011 are based entirely on patient self-report.
A one-page fibromyalgia criteria questionnaire is available and is useful in clinical trials and other research, but is “rarely, if ever” used in routine care, he said, explaining that the questionnaire contains two domains: a symptom severity score (0-12 scale) and a widespread pain index (0-19 scale).
The MDHAQ/RAPID3 is informative in RA, and has also been shown to be “useful in all rheumatic diseases in which it has been studied,” and at least three prior reports have suggested that the MDHAQ may also provide clues to the presence of fibromyalgia, Dr. Schmukler said.
“And we know from prior reports that patients with fibromyalgia reported the highest RAPID3 scores, compared to other rheumatic disease,” he added, explaining that the goal of the present study was to develop FAST cumulative indices based on the routine MDHAQ scales and using the 2011 diagnostic criteria as a reference standard.
All patients with all diagnoses seen at the Rush Medical College rheumatology clinic in Chicago complete the MDHAQ at all visits in routine care, and between April and July 2017, the fibromyalgia criteria questionnaire was also administered in 502 consecutive patients.
Of those patients, 131 met the 2011 fibromyalgia diagnostic criteria.
MDHAQ scores were analyzed for agreement with the fibromyalgia criteria questionnaire according to receiver operator characteristic curves for AUC and were compiled into three different FAST indices that included various combinations of either three or four of the MDHAQ measures that had the best agreement with the diagnostic criteria questionnaire as identified by the highest AUC values. Those were the 60-symptom checklist (AUC, 0.889), painful joint count (AUC, 0.870), fatigue visual analog scale (VAS; AUC, 0.860), and pain VAS (AUC, 0.829), Dr. Schmukler said.
Proposed cut points that reflected the optimal trade-off between specificity and sensitivity for each of the scales were scores of 6 or greater for the pain VAS and fatigue VAS, and scores of 16 or greater for the symptom checklist and painful joint count measure.
In addition to the better performance of each FAST index versus the 2011 criteria, their performance was also better than that of the RAPID3 versus the 2011 criteria (AUC, 0.848), which many clinicians use in practice without using the full MDHAQ for patient assessment, he said.
Further, the “very easily calculated” FAST indices performed as well as a “very difficult to calculate” polysymptomatic distress continuous scale derived from the fibromyalgia questionnaire to assess the degree of fibromyalgia symptoms, which had an AUC of 0.929 versus the 2011 criteria. The latter index requires complex mathematical calculations for scale conversion and thus is impractical in clinical practice, he noted.
The FAST indices also performed comparably with physician diagnoses as indicated in patient charts and with diagnoses based on tender point count as shown in prior studies.
The FAST index with the greatest sensitivity (85.5% at a cut point of 2 or greater on a scale of 1-3) was the FAST3-P, which includes pain VAS score of 6 or greater, symptom checklist score of 16 or greater, and painful joint count of 16 or greater. The FAST index with the greatest specificity (90.3% at a cut point of score of 3 or greater on a scale of 1-4) was the FAST4 index, which includes a pain VAS score of 6 or greater, fatigue VAS score of 6 or greater, symptom checklist score of 16 or greater, and painful joint count of 16 or greater.
Although the findings are limited by the lack of a gold standard for fibromyalgia diagnosis, changing diagnostic criteria, and a need for physician input for a fibromyalgia diagnosis, the study provides useful real-world data and supports findings from some prior studies with respect to the benefit of using these tools in routine practice.
With minimal extra physician time – if the MDHAQ is completed by patients at the time of registration – this approach can be used in all rheumatology patients to help identify fibromyalgia, he concluded.
Dr. Schmukler reported having no disclosures. One of his coauthors at Rush, Ted Pincus, MD, receives royalties and license fees for the copyright and trademark for the MDHAQ and RAPID3, all of which go to support clinical research.
SOURCE: Schmukler J et al. Arthritis Rheumatol. 2018;70(Suppl 10), Abstract 839.