Abstract
Objectively measurable biomarkers have not been applied for suicide risk prediction. Resting heart rate (HR) and heart rate variability (HRV) showed potential as trans-diagnostic markers associated with suicide. This study aimed to investigate the associations of resting HR and HRV on proximal suicide risk in patients with diverse psychiatric diagnoses. This chart review study used the medical records of psychiatric patients who visited the outpatient clinic at an academic tertiary hospital. A total of 1,461 patients with diverse psychiatric diagnoses was included in the analysis. Proximal suicide risk was measured using the Mini-International Neuropsychiatric Interview (MINI) suicidal score. Linear regression analyses with the MINI suicidal score as a dependent variable and binary logistic regression analyses with moderate-to-high suicide risk (MINI suicidal risk score ≥6) as a dependent variable were conducted to explore the effects of resting HR and HRV parameters on acute suicide risk after adjusting for age, sex, presence of major depressive disorder (MDD) and bipolar disorder (BD), severity of depression and anxiety severity. We found that 55 (34.6%) patients in the MDD group, 40 (41.7%) in the BD group and 36 (3.9%) in the others group reported moderate-to-high suicide risk. Linear regression analysis revealed that both resting HR and root-mean-square of successive difference (RMSSD) had significant associations with the MINI suicidal score (P = 0.037 with HR, P = 0.003 with RMSSD). In logistic regression, only RMSSD showed a significant association with moderate-to-high suicide risk (P = 0.098 with HR, P = 0.019 with RMSSD), which remained significant in subgroup analysis with patients who reported any suicide-related symptom (MINI suicidal score >0; n = 472; P = 0.017 with HR, P = 0.012 with RMSSD). Our study findings suggest the potential for resting HR and RMSSD as biomarkers for proximal suicide risk prediction. Further research with longitudinal evaluation is needed to confirm our study findings.
Highlights
Suicide is a significant mental health problem
Among the total 1,461 patients, 472 (32.3%) responded “yes” to at least one item of the Mini-International Neuropsychiatric Interview (MINI) suicide module (MINI suicidal score >0), while 229 (15.7%) showed moderate-to-high risk based on the MINI suicidal score
The mean MINI suicidal score was highest in the bipolar disorder (BD) group [6.49 standard deviation (SD) = 8.22)], followed by the major depressive disorder (MDD) group [5.01 (SD = 7.42); Table 2]
Summary
Suicide is a significant mental health problem. Extensive efforts have been made toward suicide risk prediction and prevention. The validity, reliability, and utility of current suicide risk prediction systems are unknown [1]. Heart Rate Variability and Suicidal Risk of suicidal risk prediction, objectively measurable biomarkers that can discriminate patients in an “at-risk” state are needed. Physiological biomarkers that can be measured when an individual is in an “at-risk” state are promising candidates for suicide risk monitoring. Both HR and HRV are produced by sympathetic and parasympathetic neural activity. Lower HRV is an indicator of dysregulation of cardiac autonomic function and a predictor of poor health status [2]. Short-term power spectral analysis of HRV, which has been standardized since 1996 [3], has been developed as a reliable and non-invasive tool to probe the autonomic regulation of the heart. Several studies have reported that resting HR [4, 5] and resting HRV [6] showed associations with suicide attempts
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