Psychological Pain as a Risk Factor for Suicidal Ideation: An Ecological Momentary Assessment Study on Inpatients With Depression With and Without Comorbid Borderline Personality Disorder.

Objective: Psychological pain (PP) is a potentially important risk factor for suicide. However, its temporal stability and association with suicidal ideation (SI) remain obscure. Whether PP represents a risk factor for SI independently of depression, anxiety, and hopelessness or is more prominent and temporally unstable in patients with depression and borderline personality disorder (BPD) is also unclear. Methods: From November 2020 to December 2022, psychiatric inpatients with depression without (N = 37) and with (N = 30) BPD were recruited to an ecological momentary assessment (EMA) study, wherein their PP, severity of depression, SI, and hopelessness were assessed 3 times daily using visual analog scales. Multilevel regression models were estimated. Results: Altogether, 4,320 EMA observations were collected. PP correlated with hopelessness (r = 0.417), depression (r = 0.339), and anxiety (r = 0.496), but the between-patient variance of PP remained at 1.26 (95% CI, 1.025-1.533) after controlling for these variables. The within-patient variance of PP was associated with SI (β = 0.17 [95% CI, 0.12-0.22]) with a magnitude comparable to hopelessness (β = 0.1 [95% CI, 0.05-0.15]) and depression (β = 0.12 [95% CI, 0.08-0.17]). Patients with depression and BPD reported higher daily PP and SI (P < .001) and a more prominent within-patient variation in PP. Conclusions: In psychiatric inpatients with depression, besides depression and hopelessness, PP represents an independent risk factor for SI, varying within a timescale of days. Depressive patients with BPD may experience more prominent and temporally unstable PP, likely underlying their higher vulnerability to SI.