Fibromyalgia in Patients with Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) Syndrome: Prevalence and Screening

To explore the prevalence, clinical characteristics, and screening strategy for fibromyalgia (FM) in patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. A total of 313 patients from a cohort of 354 SAPHO patients volunteered to participate in this study. Demographic, clinical and laboratory data were collected at baseline. Acute-phase reactants during the last 3 months were obtained. Patient-reported outcomes (PROs) and FM evaluation were recorded by questionnaires. A total of 57 (18.2%) patients met the 2016 research criteria for FM. Compared to those without FM, these patients had significantly higher visual analog scale (VAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI) scores (all p < 0.001). However, no differences in the erythrocyte sedimentation rate (ESR) or hypersensitive C-reactive protein (hs-CRP) levels were identified between the two groups. Patients with FM were also markedly older [odds ratio (OR) 1.072, p = 0.032] and had higher Fibromyalgia Rapid Screening Tool (FiRST) scores (OR 1.607, p = 0.016). The FiRST score showed a sensitivity of 50.9% and a specificity of 89.8%, and with a cutoff of 3, the FiRST score presented a high sensitivity of 84.2%. The prevalence of FM among SAPHO patients was similar to that among patients with other rheumatic diseases. Concomitant FM in SAPHO syndrome was associated with older age and worse PROs. Different cutoff values for FiRST screening should be used in patients with SAPHO syndrome.