Fibromyalgia influences health-related quality of life and disease activity in psoriatic arthritis.

Fibromyalgia syndrome (FMS) is common in patients of psoriatic arthritis (PsA), but the magnitude of its impact is uncertain. This cross-sectional study evaluated the impact of FMS on health-related quality of life (HRQoL) and disease activity in PsA. Adults classified with PsA (CASPAR criteria) at the rheumatology and dermatology outpatient clinics of PGIMER, Chandigarh, India between January 2014 and June 2015 were recruited. All patients were assessed for FMS using the 2010 ACR criteria. Health-related quality of life was assessed using PROMIS-HAQ, HAQ-pain, HAQ-health and revised fibromyalgia impact questionnaire (FIQR). Disease activity measures (SJC, TJC, BASDAI, enthesitis, dactylitis, PASI) and PROMIS-HAQ were correlated with measures of FMS [FIQR, symptom severity scale (SSS) score and widespread pain index (WPI)]. Multivariate regression analyses were used to identify predictors of PROMIS-HAQ and FMS. Out of 106 PsA patients screened, 102 [50 (49%) females; mean age 43.8 (12.4) years] were included. 19 (18.3%) had FMS. Patients of PsA with FMS had significantly (p < 0.05) higher TJC (14 vs 7), SJC (10 vs 5), BASDAI (6.1 vs 4.1) and enthesitis (53 vs 33%), but no difference in dactylitis, severity of skin disease and disease duration. A significant positive correlation of measures of FMS (FIQR, SSS and WPI) with SJC, TJC and BASDAI was noted. PROMIS-HAQ, HAQ-pain and HAQ-health were significantly worse (p < 0.001) in patients of PsA with coexisting FMS. Presence of FMS was found to be an independent predictor of worse PROMIS-HAQ. Female gender and higher TJC independently predicted presence of FMS. To conclude, FMS is an important contributor towards poor HRQoL in patients of PsA and is associated with higher values of joint disease activity measures.