Background Oxytocin, which is also called a happy hormone, has been reported to be related to various conditions including depressive state. However, the positioning of oxytocin in rheumatoid arthritis (RA) remains unclear.
Objectives The objective of this study was to investigate the relationship between serum oxytocin levels and disease activity, depressive state, activity of daily life (ADL), and quality of life (QOL) in RA.
Methods The study included 20 patients with RA who received treatment with a biological agent. We measured the following items before and at 6 months after the start of treatment. The baseline characteristics included the age, sex, prednisolone dose, methotrexate dose, duration of disease, anti-cyclic citrullinated peptide antibody (anti-CCP antibody), rheumatoid factor (RF), serum matrix metalloproteinase-3 (MMP-3), erythrocyte sedimentation rate, and C-reactive protein (CRP). The disease activity of rheumatoid arthritis was assessed using the Simplified Disease Activity Index (SDAI), depressive state using Hamilton Depression Rating Scale (HAM-D), ADL using the Health Assessment Questionnaire (HAQ), and QOL using the 36-Item Short Form Health Survey (SF-36). Serum oxytocin levels were determined by enzyme-linked immunosorbent assay (ELISA). The correlation between each item and the serum oxytocin levels were examined.
Results The serum oxytocin levels before the start of treatment were correlated with RF (r=−0.529), HAQ (r=0.446), HAM-D (r=0.508), and among the 8 categories of the SF-36, physical function (r=−0.676), role function (physical) (r=−0.801), pain (r=−0.506), general health perception (r=−0.787), role function (emotional) (r=−0.844), and mental health (MH) (r=−0.516). On the other hand, the serum oxytocin levels did not correlate with the SDAI (r=−0.078). The serum oxytocin levels after the start of treatment were correlated with the age (r=−0.549), SDAI (r=−0.539), HAQ (r=0.813), HAM-D (r=0.584), and all of the SF-36 categories except for MH (r=0.038) (r>0.4). Other items did not correlate to the serum oxytocin levels.
Conclusions The serum oxytocin levels before the start of treatment were correlated with depressive state, ADL, and QOL but not with disease activity. Those after the start of treatment were correlated with the SDAI, depressive state, ADL, and QOL.
Disclosure of Interest Y. Miwa Grant/research support from: Tanabemitsubishi, Chugai, phizer, Ono, R. Takahashi: None declared, S. Isojima: None declared, M. Saito: None declared, Y. Miura: None declared, S. Ishii: None declared, Y. Ikari: None declared, T. Tokunaga: None declared, T. Kasama: None declared, Y. Toyoshima: None declared, K. Inagaki: None declared