Abstract
OBJECTIVE: To observe how osteoarthritis (OA) and degree of fatigue affect are associated with pain levels in patients with fibromyalgia syndrome (FMS). METHODS: A cross-sectional study was conducted involving FMS patients. Data regarding the clinical features of the patients, including scores for pain-Visual Analogue Scale (VAS), Fatigue Scale-14 (FS-14) and other patient information, was collected. A multivariable logistic regression model was constructed to determine whether there is a true association between OA, degree of fatigue, and pain level in FMS patients. Restricted cubic spline (RCS) analysis was used to explore a potential non-linear relationship between degree of fatigue scores and pain levels in FMS patients. An interaction analysis based on the main regression model was performed to examine the interaction between OA and degree of fatigue. RESULTS: Among the FMS patients, the presence of OA was identified as a risk factor associated with higher pain-VAS scores (OR=2.777, 95% CI=1.377-5.601, P=0.004); furthermore, higher degree of fatigue scores on the FS-14 were found to be significantly associated with high pain level (OR=1.145, 95% CI=1.054-1.243, P=0.001). The RCS analysis demonstrated a linear relationship between increasing FS-14 scores and an elevated risk of high pain levels among FMS patients (P-non-linear=0.119, P-overall=0.008). The interaction analyses revealed a significant association between OA and degree of fatigue, which were related to the pain level of patients with FMS synergistically. CONCLUSION: Patients with FMS experience coexisting OA and a high degree of fatigue, which interact synergistically, being correlated with increased pain levels. TRIAL REGISTRATION: The study was approved by the Clinical Research Ethics Committee of the China-Japan Friendship Hospital (2022-KY-079) and registered on ClinicalTrials.gov (NCT05508516) on August 17th, 2022.