OBJECTIVES: Our aims were (1) to measure respiratory sinus arrhythmia (RSA), a high-frequency spectrum component of heart rate variability (HRV) in mood-disordered suicide attempters and (2) to investigate the relationship of RSA to symptoms and length of hospitalization.
METHODS: Forty-nine female repetitive-suicide attempters with depressive disorder or bipolar disorder were recruited in a general hospital setting. Manic or psychotic patients were excluded. Resting RSA values were calculated from electrocardiogram data, and severity of clinical presentation shortly after admission and length of hospital stay were assessed.
RESULTS: RSA was positively associated with a higher Beck Scale for Suicidal Ideation score (r = 0.33 P = 0.019). Stepwise multiple regression analysis showed a significant correlation between RSA and hospitalization length after adjusting other variables (beta coefficient = 3.00; P = 0.030). Patients with a higher resting RSA had more prolonged hospitalizations (hospitalization beyond 30 days) after controlling for other variables (odds ratio = 5.08, P = 0.017).
CONCLUSIONS: Interaction between the environment and the autonomic nervous system is complex. Further and more comprehensive research is needed.