Exploring the prevalence and clinical impact of fibromyalgia syndrome in patients with shoulder diseases: a cross-sectional study

Objectives: Fibromyalgia (FM) is a musculoskeletal syndrome characterised by widespread chronic pain often associated with systemic manifestations such as mood disturbances, persistent fatigue, unrefreshed sleep, and cognitive impairment, substantially impacting patients' health-related quality of life. Based on this background, this study aimed to evaluate the prevalence of FM syndrome in patients referring to an outpatient clinic in a central orthopaedic institute for a painful shoulder. The demographic and clinical characteristics of patients fulfilling the criteria for FM syndrome were also correlated with the severity of symptoms. Methods: Consecutive adult patients referring to the shoulder orthopaedic outpatient clinic of the ASST Gaetano Pini-CTO, Milan, Italy, to undergo a clinical evaluation were assessed for eligibility in an observational, cross-sectional, monocentric study. Results: Two hundred-one patients were enrolled: 103 males (51.2%) and 98 females (48.8%). The mean age ± standard deviation (SD) of the patients was 55.3 ± 14.3 years in the whole population. Of all the patients, 12 (5.97%) fulfilled the 2016 FM syndrome criteria based on the FM severity scale (FSS). Of these, 11 were females (91.7%, p=0.002). The mean age (SD) was 61.3 (10.8) in the positive criteria sample. Patients with positive criteria had a mean FIQR of 57.3 ± 16.8 (range 21.6-81.5). Conclusions: We found that FM syndrome is more frequent than expected in a cohort of patients referring to a shoulder orthopaedic outpatient clinic, with a prevalence rate (6%) more than double that of the general population (2%).