Sleep Disordered Breathing

New, Low-Cost Screening Process for Obstructive Sleep Apnea

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Measuring the oxygen desaturation index (ODI) with overnight pulse oximetry is an effective, low-cost way to screen for obstructive sleep apnea (OSA), a new study published in the Journal of Clinical Sleep Medicine suggests.
OSA is often underrecognized in hospitalized patients and associated with significant morbidity and mortality, according to researchers from Thomas Jefferson University and Hospitals, in Philadelphia.
“Sleep disordered breathing is associated with cardiovascular complications and sudden death,” said lead study author Sunil Sharma, MD, FAASM, associate professor of pulmonary medicine in the Sidney Kimmel Medical College at Thomas Jefferson University, in a press release.
The researchers conducted a prospective study with 754 patients to test the efficacy of this screening for identifying OSA in patients admitted to a tertiary care hospital. The patients were admitted between February 2013 and February 2014.
Obese patients (body mass index >30 kg/m2) were automatically screened for OSA—being overweight is a risk factor for OSA—using the STOP (snoring, tiredness during daytime, observed apnea, high blood pressure) questionnaire. Patients with positive results were advised to have a follow-up evaluation, which included an overnight polysomnography.
The optimal screening cutoff for OSA was ODI greater than or equal to 10 events per hour (Matthews correlation coefficient, 0.36; 95% CI, 0.24-0.47). The researchers found that 129 of the 149 patients who underwent polysomnography were shown to have OSA.
“The results showed that our screening process identified sleep disordered breathing in 87% of patients who followed up with a polysomnography,” said Dr. Sharma. “We confirmed the high prevalence of undetected sleep-disordered breathing among hospitalized patients and also validated a low-cost protocol to detect it.”
The authors noted a significant increase in the number of hospitalized patients recommended to undergo polysomnography after implementing this screening process.
“This study should be of great interest to hospitals looking at ways to reduce complications,” said Dr. Sharma. “Recent data suggests that for inpatients with cardiovascular disorders, early diagnosis and intervention for sleep apnea may lead to reduced readmission rates.”

Sleep Disordered Breathing (SDB) and Cancer Mortality.

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Sleep disordered breathing (SDB) has been associated with total and cardiovascular mortality, but an association with cancer mortalityhas not been studied. Results from in vitro and animal studies suggest that intermittent hypoxia promotes cancer tumor growth. The goal of the present study was to examine whether SDB is associated with cancer mortality in a community-based sample.

METHODS:

We used 22-year mortality follow-up data from the Wisconsin Sleep Cohort sample (n=1522). SDB was assessed at baseline with full polysomnography. SDB was categorized using the apnea-hypopnea index (AHI) and the hypoxemia index (percent sleep time below 90% oxyhemoglobin saturation). The hazards of cancer mortality across levels of SDB severity were compared using crude and multivariate analyses.

MEASUREMENTS AND MAIN RESULTS:

Adjusting for age, sex, body mass index, and smoking, the SDB was associated with total and cancermortality in a dose-response fashion. Compared to normal subjects, the adjusted relative hazards of cancer mortality were 1.1 [95% confidence interval (CI), 0.5-2.7] for mild SDB (AHI 5-14.9), 2.0 (95% CI, 0.7-5.5) for moderate (AHI 15-29.9), and 4.8 (95% CI, 1.7-13.2) for severe SDB (AHI≥30) (p-trend=0.0052). For categories of increasing severity of the hypoxemia index, the corresponding relative hazards were 1.6 (95% CI, 0.6, 4.4), 2.9 (95% CI, 0.9-9.8), and 8.6 (95% CI, 2.6-28.7).

CONCLUSIONS:

Our study suggests that baseline SDB is associated with increased cancer mortality in a community-based sample. Future studies that replicate our findings and look at the association between sleep apnea and survival after cancer diagnosis are needed.

Source: BMJ