Accepted for/Published in: JMIR Formative Research
Date Submitted: Oct 10, 2023
Date Accepted: Jan 24, 2024
Changepoint Detection in Heart Rate Variability Indices in End-of-Life Non-Cancer Older Patients Using Ballistocardiography Signals: A Preliminary Retrospective Study
ABSTRACT
Background:
In end-of-life care outside the hospital, it is important to monitor patients to understand their condition and predict survival time because this information gives family members and/or caregivers time to prepare for the patient’s end-of-life. However, this is difficult as there are limited resources available for this purpose.
Objective:
The purpose of this preliminary retrospective study was to determine whether and how changes in heart rate variability (HRV) indices estimated using ballistocardiography (BCG) occur before the date of death in terminally ill elderly patients, and ultimately to predict the date of death.
Methods:
This retrospective pilot study assessed the medical records of 15 elderly patients admitted to a special elderly nursing home between August 2019 and December 2021. Patient characteristics and time-domain HRV indices such as the average normal-to-normal (NN) interval (ANN), standard deviation of the NN interval (SDNN), and root mean square of successive differences (RMSSD) were collected. The overall trends in the indices were examined by drawing a restricted cubic spline curve. Repeated-measures analysis of variance (ANOVA) was performed to evaluate changes in the indices over the observation period. The changepoints of HRV indices were estimated using piecewise regression analysis.
Results:
The study population comprised patients (eight men and seven women) with a median age of 93.5 years. The cubic spline curve showed a gradual decline in the indices approximately 30 days before the patient’s death. Repeated-measures ANOVA showed that the ratio of the geometric mean of ANN (0.90 [95%CI: 0.84, 0.98], P=.005) and RMSSD (0.83 [95%CI: 0.70, 0.99], P=.03) began to decrease 3 weeks before death compared to values at 8 weeks before death. Piecewise regression analysis estimated the changepoint for ANN, SDNN, and RMSSD to be -34.5 (95% confidence interval [CI]: -42.5, -26.5) days (P<.001), -33.0 (95%CI: -40.9, -25.1) days (P<.001), and -35.0 (95%CI: -42.3, -27.7) days (P<.001), respectively, before death.
Conclusions:
This preliminary study identified the changepoint of HRV indices before death in end-of-life elderly patients. Although a small amount of data was examined, our findings indicate that HRV indices from BCG can be useful for monitoring and predicting survival time in end-of-life elderly patients.
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