Development and validation of the SImple FIbromyalgia Screening questionnaire for improving the recognition of fibromyalgia in daily practice

OBJECTIVES: To develop and test in a preliminary way a new self-administered and user-friendly screening tool, called SImple FIbromyalgia Screening (SIFIS) questionnaire, to screen Italian speaking patients for the presence of fibromyalgia (FM). METHODS: The development of the SIFIS questionnaire followed five steps: identification of a specific patient population, item pool development, item reduction, test of the provisional questionnaire, and validation study. The item generation was carried out by a review of the literature on the existing questionnaires. Thirty-three items were identified, and a survey was performed among 139 specialists. The frequency importance product allowed us to select the six most significant items. The validation study allowed the determination of sensitivities, specificities and likelihood ratios (LRs) aiming to calculate the post-test probability of the presence of FM, by applying the Bayesian Analysis Model method. RESULTS: The preliminary testing was performed in 284 subjects with multi-site pain. In 230 (80.9%) of them, FM was diagnosed according to the modified 2010 American College of Rheumatology (ACR) criteria. For each of the six items, LRs varied between 3.37 and 5.00. The best positive LR was found in item 1, exploring persistent pain. The presence of four out of six items gave a post-test probability ≥80% (range: 81.8-87.1%). CONCLUSIONS: The SIFIS questionnaire is a useful tool that can be used for potential screening.