Elevated Salivary Alpha-Amylase Level, Association Between Depression and Disease Activity, and Stress as a Predictor of Disease Flare in Systemic Lupus Erythematosus: A Prospective Case–Control Study

Psychological stress has been shown to trigger systemic lupus erythematosus (SLE). However, objective evidence of symptom aggravation due to mental stress is difficult to identify. We aimed to investigate the relationship between SLE disease activity and mental stress, and the usefulness of saliva as an assessment index for stress in patients with SLE. We prospectively assessed the salivary stress hormone and disease-related biomarkers, and questionnaire data regarding stress and depression in 100 patients with SLE and 49 sex- and age-matched normal controls (NCs). Patients with SLE had higher mean salivary α-amylase levels (5.7 ± 4.6 U/mL vs 2.7 ± 2.5 U/mL, P < 0.001), anti-chromatin antibody levels (25.3 ± 22.9 U/mL vs 15.9 ± 10.9 U/mL, P < 0.001), and Beck Depression Index (BDI) scores (11.1 ± 9.2 vs 5.3 ± 5.1, P < 0.001) than NCs. However, salivary cortisol levels and Perceived Stress Scale (PSS) scores did not differ between the groups. The BDI scores correlated with the SLE disease activity index (SLEDAI) scores (r = 0.253, P = 0.011) and erythrocyte sedimentation rates (r = 0.234, P = 0.019). SLE patients with the highest-quartile PSS scores had significantly increased SLEDAI scores compared to those with the lowest-quartile PSS scores after 4 to 5 months’ follow-up. Moreover, SLE patients with elevated SLEDAI scores had higher baseline PSS scores. Patients with SLE showed uncoupling of the sympathetic nervous system and hypothalamic–pituitary–adrenal axis; higher salivary α-amylase and no different cortisol levels compared with NCs. Also, patients with SLE were more depressed, which correlated with disease activity. Furthermore, perceived stress was not correlated with disease activity; however, disease activity worsened several months later with elevated perceived stress levels.