Night-to-night fluctuations in sleep apnea severity: diagnostic and treatment implications

Study Objectives: Sleep apnea is a common disorder with serious consequences; however, effective treatments are available. Successful implementation of treatment strategies relies on accurate diagnosis, which may be hampered by the presence of substantial nightly fluctuation in sleep apnea severity. We examined the amount of nightly fluctuation in the severity of sleep apnea around commonly used diagnostic and treatment cut points in individuals who underwent two nights of home sleep apnea testing (HSAT). Methods: A nationwide retrospective cohort study of adults thought to have sleep apnea underwent two nights of HSAT between 2005 and 2017. Results: The study included 47,423 adults (mean age, 55.2 [14.6] years; 53.7% male). The average apnea-hypopnea index (AHI) for the sample was 26.9. The average amount of nightly fluctuation in AHI was 5.5. More than a third of the sample, 16,115 individuals, had fluctuations between diagnostic cut points across the two nights of HSAT. The negative predictive value of the HSAT in the first night was 47.42%, 73.57%, and 88.65% for detecting an AHI >= 5, AHI >= 15, and AHI >= 30, respectively. Conclusions: The addition of a second night of HSAT has the potential to reduce the likelihood of missed diagnoses that could result from nightly fluctuation in the severity of sleep apnea.