Background/Purpose: The odds of patients with rheumatoid arthritis (RA) experiencing depression is 1.42 (95% CI: 1.3–1.5; approximately 15% of patients) compared with healthy individuals. Diagnosis of depression is based on an interview, which is subjective to both psychiatrist and patient, and auxiliary diagnoses such as a self-rating scale for depression are uncertainty. Phosphoethanolamine (PEA), a plasma biomarker, has been reported to be a useful diagnostic biomarker for depression. We examined the efficacy of PEA as a biomarker for RA-associated depression.

Methods: This study included 52 registered RA patients who were recruited between 2019 and 2020. Patients provided written informed consent to participate and the study was approved by the Institutional Ethics Committee of the Showa University. The following background factors were investigated: age, sex, and disease duration. RA disease activity was evaluated using the Simplified Disease Activity Index. The depression status was evaluated using the Patient Health Questionnaire (PHQ)-9 as a standard scale. Questionnaires for depression, anxiety, and ego were also performed. Items of these questionnaire were converted into Scale A (depression/anxiety scale) and Scale B (adaptation scale). Plasma PEA was measured in Human Metabolome Technologies Inc. Statistical analysis was performed using the chi-square test and one-way analysis of variance.

Results: Forty-nine RA patients with no missing data were included in the analysis. The PHQ-9 score, the gold standard, was used to stratify patients by disease severity—normal, 33; mild depression, 12; moderate depression, 3; and severe depression, 1. Each group was compared between groups.

①The patient visual analog scale (VAS) score was significantly high among patients with depression (p = 0.00157). The difference in VAS scores of patients and doctors was significantly high considering patients with depression (p = 0.00409).

②The Scale A score was significantly high among patients with depression (p = 1.19 × 10⁻¹⁰), and the ratio of Scale A score to PEA was significantly high (p = 1.64 × 10⁻⁷) among patients.

③A significant difference was noted between the groups for the plasma PEA concentration (p = 0.0272). The plasma PEA concentration was low in patients with mild and moderate depression and high in a patient with severe depression.

④The Scale B score tended to be higher among patients with depression compared with others, without significant difference.

Conclusion: Plasma PEA alone presents a weak performance as a diagnostic biomarker for depression in patients with RA. However, a composite measure for diagnosing depression, including questionnaires for depression, anxiety, and ego may be used as an auxiliary diagnosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-of-plasma-phosphoethanolamine-as-a-biomarker-for-rheumatoid-arthritis-associated-depression/