Validity of actigraphy for nighttime sleep monitoring in hospitalized patients with traumatic injuries

Abstract

Study objectives: Sleep-wake disturbances are frequent among patients hospitalized for traumatic injuries but remain poorly documented due to the lack of tools validated for hospitalized patients. This study aimed to validate actigraphy for nighttime sleep monitoring of hospitalized patients with severe traumatic injuries, using ambulatory polysomnography (PSG). Methods: We tested 17 patients (30.4 ± 14.7 years, 16.6 ± 8.2 days post-injury) who suffered severe orthopedic injuries and/or spinal cord injury, with or without traumatic brain injury. When medically stable, patients wore an actigraph on a non-paralyzed arm and underwent ambulatory PSG at the bedside. Data were converted to one-minute epochs. The following parameters were calculated for the nighttime period: total sleep time, total wake time, sleep efficiency and number of awakenings. Epoch-by-epoch concordance between actigraphy and PSG was analyzed to derive sensitivity, specificity and accuracy. PSG sleep parameters were compared to those obtained from four actigraphy scoring algorithms by Bland-Altman plotting. Results: Sensitivity to detect sleep was ≥92% and accuracy was >85% for all four actigraphy algorithms used, while specificity varied from 48-60%. The low-activity wake threshold (20 activity counts per epoch) was most closely associated with PSG on all sleep parameters. This scoring algorithm also had the highest specificity (59.9%) and strong sensitivity (92.8%). Conclusions: Actigraphy is valid for monitoring nighttime sleep and wakefulness in patients hospitalized with traumatic injuries, with sensitivity, specificity and accuracy comparable to actigraphic recordings in healthy subjects. A scoring algorithm using a low wake threshold is best suited for this population and setting.