UTILITY OF NOCTURNAL HOME OXIMETRY FOR CASE-FINDING IN PATIENTS WITH SUSPECTED SLEEP-APNEA HYPOPNEA SYNDROME

Objective: To evaluate prospectively the validity of home oximetry for case finding in patients clinically suspected of having the sleep apnea hypopnea syndrome (SAHS). Design: Blinded comparison of home oximetry and polysomnographic nocturnal recordings. Setting: Sleep clinic of a tertiary referral center. Patients: A total of 240 outpatients referred because of reported sleep disturbances or daytime hypersomnia compatible with the diagnosis of SAHS. Measurements: All participants had nocturnal home oximetry followed by a conventional polysomnographic study. The two recordings were interpreted blindly. Home oximetry test results were classified as abnormal (suspicion of sleep-related breathing abnormalities) in the presence of repetitive, short-duration arterial oxyhemoglobin saturation (Sa(O2)) fluctuations without any absolute or relative decrease in the Sa(O2) threshold. The diagnosis of SAHS was confirmed when the apnea-plus-hypopnea index was greater than 10. Results: Based on the results of the polysomnographic sleep study, 110 patients had SAHS (apnea-plus-hypopnea index, 38.1 +/- 2.5/h; mean +/- SE). Home oximetry test results were interpreted as abnormal in 176 patients (this included 108 patients with SAHS and 68 without SAHS) and were read as normal in 62 patients without SAHS and in 2 with SAHS. Home oximetry testing had a sensitivity of 108/110 or 98.2% (95% CI, 93.6% to 99.8%); a specificity of 62/130 or 47.7% (CI, 38.8% to 56.6%); a positive predictive value of 108/176 or 61.4%; and a negative predictive value of 62/64 or 96.9%. Conclusions: A negative home oximetry test result is helpful in ruling out the diagnosis of SAHS in patients clinically suspected of having this syndrome, because a negative test result reduced the probability from 54.1% to 3.1% in our patients. However, a positive oximetry test increased the probability from 46% to 61.4% in our group of patients.