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

Objective 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). Conclusion 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%).