Abstract
BACKGROUND: We examined the effects of insomnia and diurnal rest-activity rhythms (RARs) on time to hospitalizations and emergency department (ED) visits in a randomized controlled trial of cognitive behavioral therapy for insomnia among people with chronic heart failure (HF) and insomnia. METHODS: Among 168 HF patients, we measured insomnia, CPAP use, sleep, symptoms, and 24-h wrist actigraphy and computed the circadian quotient (strength of the RAR) from wrist actigraphy and computed cox-proportional hazard and frailty models. RESULTS: Eighty-five (50.1%) and ninety-one (54.2%) participants had at least one hospitalization or ED visit, respectively. NYHA class and comorbidity predicted time to hospitalizations and ED visits, while younger age and male sex predicted earlier hospitalizations. Low ejection fraction predicted time to first cardiac event and composite events. Independent of clinical and demographic predictors, a lower circadian quotient and more severe pain significantly predicted earlier hospitalizations. A more robust circadian quotient, more severe insomnia, and fatigue predicted earlier ED visits independent from clinical and demographic factors. Pain and fatigue predicted composite events. CONCLUSION: Insomnia severity and RARs independently predicted hospitalizations and ED visits independent of clinical and demographic variables. Further research is necessary to determine whether improving insomnia and strengthening RARs improves outcomes among people with HF. CLINICAL TRIALS REGISTRATION: NCT02660385.