Association Between Suicidal Ideation and Negative Affect: 6-Month Ecological Momentary Assessment Study.

Background: Suicide is a major public health challenge. Traditional assessments of suicidal thoughts and behaviors rely on retrospective measures that are subject to recall bias and show limited predictive accuracy. Ecological momentary assessment (EMA) can improve suicide risk assessment by capturing real-time information in participants' natural environments. However, EMA burden often results in short follow-up periods. Objective: This study aimed to examine the association between suicidal ideation (SI) and multiple variables collected in real time using smartphone-based EMA over 6 months, with the goal of identifying short-term predictors of suicide risk in a clinical population. A secondary objective was to explore whether baseline depression and psychological pain predicted EMA-reported SI. Methods: This is a prospective EMA-based study carried out among outpatients at high risk of suicide, recruited in Madrid, Spain. At baseline, depression, suicidality, and psychological and physical pain were assessed using traditional questionnaires (Inventory of Depressive Symptomatology, Columbia Suicide Severity Rating Scale, and Visual Analog Scales). During the 6-month follow-up, participants completed daily smartphone-based EMA prompts assessing SI, nonsuicidal self-injury, negative affect, interpersonal experiences, sleep, and eating habits. Each day, 2-4 questions derived from validated instruments were randomly selected from a pool of 34 items to minimize participant burden. Mixed-effects models examined within-person variability, temporal trends, and real-time associations between EMA variables and SI. Intraindividual variability was quantified using intraclass correlation coefficients and root mean squared successive differences. Linear regression analyses explored associations between EMA variables and demographic covariates and evaluated whether baseline depression and psychological pain predicted the mean and variability of SI and negative affect. Results: A total of 99 participants were included in the final analysis, and 13,900 EMA responses were obtained. The slope of SI showed no significant changes over time, with similar results for negative affect, interpersonal difficulties, sleep problems, and appetite. Substantial within-person variability was observed across all EMA domains. Negative affect (ß=0.193, SE 0.03; Conclusions: This study provides novel insights into the real-time relationship between SI and key psychological and behavioral variables, particularly negative affect and interpersonal difficulties, using smartphone-based EMA in a high-risk clinical population. The substantial within-person variability highlights the dynamic nature of suicide risk and the limitations of traditional assessments. Future studies should aim to translate EMA-based monitoring into actionable interventions to provide real-time support for individuals at high risk of suicide.