Greater risk of hospitalization from influenza infection is possible in patients with obstructive sleep apnea (OSA) who do not use continuous positive airway pressure (CPAP), according to study results from the Journal of Clinical Sleep Medicine.

The association between influenza infection and underlying pulmonary conditions have increased the need to mitigate the risk of influenza severity. Study researchers sought to determine the correlation between patients with OSA and laboratory-confirmed influenza by using medical records from Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire.

In this retrospective study, patients were over 18 years of age and were excluded if medical information was missing or incomplete. Between 2016 and 2018, study researchers analyzed 231 medical records, confirmation of influenza, type of influenza infection, OSA severity through the apnea-hypopnea index (AHI), and whether the patient was hospitalized.

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Adherence to CPAP was analyzed and defined as at least 70% of nights of CPAP use with no less than 4 hours per night on the data download. Researchers placed patients who were nonadherent to CPAP into mild (AHI, 5 to 14 events/h), moderate (AHI, 15 to 29 events/h), and severe (AHI, >30 events/h) categories. The time between influenza diagnosis and CPAP download had an average span of 5.5 months with similar patient characteristics. Additionally, study researchers reviewed vaccination records, considering patients as immunized if they had a record of influenza vaccine administration prior to the date of diagnosis.

Of the 231 records reviewed, 147 were confirmed with influenza infection and others were excluded due to missing or incomplete information. The remaining 53 medical records consisted of 28 patients who were nonadherent and 25 patients who were adherent to CPAP treatment. Nonadherent patients were more likely to be hospitalized with influenza infection (odds ratio, 4.7; 95% CI, 1.3 to 19.5, P =.01) with no significant higher occurrence of influenza complications (P =.10).

Among the patients who were nonadherent to CPAP, there were no significant differences in hospitalizations (P =.13). However, documented vaccination rates were higher in 21 (75%) of the 28 nonadherent patients compared with 14 (56%) of the 25 patients who were adherent to CPAP. This did not have statistical significance (P =.28).

Limitations of this study include the small amount of included patients, the limited data on confounding variables, and the large amount of excluded records due to incomplete or missing information.

Study researchers concluded that their findings suggested that “treatment of OSA with CPAP may help reduce the chance of hospitalization after influenza infection among patients with OSA.” The significant mortality and morbidity associated with influenza encourage the need to improve adherence to CPAP in an effort to avoid hospitalization.


Mok EM, Greenough G, Pollack CC. Untreated obstructive sleep apnea is associated with increased hospitalization from influenza infection. J Clin Sleep Med. Published online December 15, 2020. doi:10.5664/jcsm.8744

This article originally appeared on Neurology Advisor