Validity and Reliability of the Fibromyalgia Rapid Screening Tool Among Individuals with Chronic Daily Headache: A Clinic-Based Study.

Fibromyalgia is a common chronic pain disorder typically associated with headache disorders, particularly chronic daily headache. However, fibromyalgia is typically underdiagnosed and undertreated. The Fibromyalgia Rapid Screening Tool questionnaire is a brief, self-administered questionnaire composed of six "yes/no" questions for detecting fibromyalgia. The Fibromyalgia Rapid Screening Tool questionnaire has demonstrated high sensitivity and specificity among patients with chronic diffuse pain conditions. This study assessed the validity and reliability of the aforementioned questionnaire for detecting fibromyalgia among patients with chronic daily headache.Consecutive first-visit headache patients with primary chronic daily headache (≥15 days/month for three or more months) at the outpatient clinics of four university hospitals were enrolled in this study from April 2015 to October 2015, and the validity and reliability of the Fibromyalgia Rapid Screening Tool questionnaire for determining fibromyalgia were evaluated. Fibromyalgia was diagnosed according to the American College of Rheumatology criteria of 2010.A total of 171 patients with primary chronic daily headache were recruited, and 100 (58.4%) were determined to have fibromyalgia. Receiver operating characteristic curve analysis revealed that a cutoff score of 5 (corresponding to the number of positive items) provided the highest rate of correct identification of patients (77.2%), with a sensitivity of 70.0% and specificity of 87.3%. The positive and negative predictive values were 88.6% and 67.4%, respectively. The Cronbach's alpha coefficient was 0.684.The Fibromyalgia Rapid Screening Tool is a valid and reliable instrument for identifying fibromyalgia among patients with chronic daily headache.