Study objective: Determine the utility of nocturnal oximetry as a screening tool for sleep apnea-hypopnea syndrome (SAHS) compared with polysomnography (PSG).
Design: Cost-effectiveness analysis based on retrospective review of overnight sleep studies.
Setting: United States Air Force tertiary teaching hospital.
Patients: One hundred consecutive patients evaluated for SAHS by overnight sleep study.
Intervention: Participants underwent PSG and oximetry on the same night. Patients with obstructive sleep apnea had a continuous positive airway pressure trial.
Measurements: Oximetry was abnormal when > or =10 events per hour occurred. Two criteria were evaluated. A "deep" pattern of > 4% change in oxyhemoglobin saturation to < or =90%, and a "fluctuating" pattern of repetitive short-duration fluctuations in saturation. The diagnostic accuracy of both methods was compared with PSG. Cost-effectiveness of screening oximetry was compared with PSG alone and use of split-night studies.
Results: The fluctuating pattern had a greater sensitivity and negative predictive value, while the deep pattern had a greater specificity and positive predictive value. Oximetry screening using the fluctuating pattern was not as sensitive as PSG for detecting patients with mild disease; 17 of 28 patients (61%) with normal oximetry results had treatable conditions detected by PSG. Cost analysis showed that screening oximetry would save $4,290/100 patients but with considerable loss of diagnostic accuracy.
Conclusion: Screening oximetry is not cost-effective because of poor diagnostic accuracy despite increased sensitivity using the fluctuating pattern. Greater savings, without loss of diagnostic accuracy, may be achieved through increased utilization of split-night PSGs.