VANCOUVER, B.C. – A significant number of hospitalized patients are at high risk for obstructive sleep apnea, but few have been evaluated for OSA, Dr. Sunita Kumar reported at the annual meeting of the American College of Chest Physicians.
Because OSA has been shown to increase the risk of adverse outcomes such as stroke and heart failure, screening inpatients might help prevent complications. However, Dr. Kumar noted, the diagnosis and treatment of OSA in hospitalized patients have not been shown to affect outcomes.
Of 195 inpatients surveyed over a 24-hour period at Loyola University Medical Center in Maywood, Ill., 157 (81%) were found to be at high risk for OSA. Of those, 41 had undergone a previous sleep study, and of the 41 patients who had been evaluated, 31 were found to have OSA, said Dr. Kumar of the Division of Pulmonary and Critical Care Medicine at Loyola.
In comparison, 5% of the general population is estimated to have sleep apnea.
The patients had a mean age of 62 years, and 82% were older than 50 years. Their mean body mass index was 28 kg/m2, with 14% having a BMI over 35. More than half (59%) were men. Of the 31 patients with a previous diagnosis of OSA, 17 were using continuous positive airway pressure (CPAP), 1 had undergone surgery, and 13 were not receiving treatment, generally because of nontolerance of CPAP.
The patients were screened using the STOP-BANG questionnaire, which has high sensitivity for detecting a high risk of sleep apnea but is not very specific, Dr. Kumar reported. It has also not been validated in inpatients, she said, which was a limitation of the study. However, the STOP-BANG (snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, and gender) questionnaire has been reported to be of high quality for predicting OSA (Can. J. Anaesth. 2010;57:423-38). When these patients were evaluated using only the STOP portion of the survey, 65% were found to be at high risk.
The few previous studies that looked at OSA in hospitalized patients found the prevalence to be as high as 77% (J. Clin. Sleep Med. 2008;4:105-10; Sleep Breath. 2008;12:229-34).
The take-home point of the recent study might be that it is safer to make a presumptive diagnosis of OSA in inpatients, commented session moderator Dr. Rochelle Goldberg, president and chief medical officer of the American Sleep Apnea Association.
Also at the session, Dr. Dennis Auckley presented his study on the frequency of complications in 217 hospitalized patients divided into three groups: those with known OSA (36 patients, 17%), those determined to be at high risk using the STOP and Berlin questionnaires (106 patients, 49%), and those at low risk (75 patients, 35%) based on the questionnaires.
The patients’ mean age was 50 years. Those with known OSA had a mean BMI of 44, the high-risk patients had a mean BMI of 32, and the low-risk patients had a mean BMI of 28.
Dr. Auckley of Case Western Reserve University in Cleveland and his colleagues undertook their 4-month, prospective observational study to further explore earlier findings that patients with OSA experience more adverse outcomes in the perioperative setting (Chest 2008;133:1128-34).
In their study, 38% of those with diagnosed OSA, 22% of those at high risk, and 14% of the low-risk patients experienced complications. Hypoxemia was the most frequent complication. The difference in complication rate between the known OSA patients and the low-risk patients was significant, even after researchers controlled for age, diagnosis, and comorbidities.
Patients with sleep apnea more commonly experience complications, especially hypoxemia, while hospitalized, Dr. Auckley concluded. The questionnaires have not been validated in hospitalized patients, and the patients were not monitored by oximetry, which were two limitations of the study, he noted.
Dr. Kumar reported that she had no relevant financial conflicts. Dr. Auckley disclosed support from ResMed Corp., and Cephalon Inc., and has received equipment from Cleveland Medical Devices Inc. His current study received no funding.