The aim of this study is to assess the accuracy of nocturnal pulse oximetry as a confirmatory test in the diagnosis of obstructive sleep apnea (OSA) as against polysomnography (PSG) which is the gold standard.
Patients referred to the sleep center for PSG with symptoms suggestive of OSA were investigated. Full night diagnostic polysomnography with oximetry was performed at the sleep center. Baseline characteristics were taken. Respiratory disturbance index (RDI) and lowest O2 saturation (LSAT) levels were determined for each patient. 5 LSAT threshold values (75%, 80%, 85%, 90% and 95%) were obtained for analysis. Sensitivity, specificity, false positive rate, positive predictive values (PPV) and negative predictive values were computed for each threshold level. Receiver operating characteristic (ROC) curve was constructed to measure the diagnostic performance of LSAT.
416 were included in the present study after meeting the inclusion criteria. The group consisted of 315 (75%) men and 101 (25%) women. Mean age ± SD was 46.02± 12.07. The average BMI± SD was 29.04± 6.10. The mean RDI was 33.27± 36.37. 284 patients had an RDI of ≥5/hour. Of these 244 (86%) were men and 40 (14%) were women. When compared statistically, there was a significant difference in the BMI and LSAT. Correlation of RDI ≥5/hour with LSAT was statistically significant at p=0.000 with an r=−0.662. Using LSAT threshold of 85% gave a sensitivity of 83%, specificity of 90% with FPR of 10%, PPV of 95% and NPV of 72%. AUC=0.93.
A level of 85% may suggest that these patients has OSA
For adults who are unlikely to have OSA clinically, a negative oximetry result may be sufficient to exclude the diagnosis; for adults who are likely to have OSA clinically, a positive oximetry result may be sufficient to confirm the diagnosis of OSA and therefore would benefit from treatment to prevent the complications of OSA.
F.C. Corpuz, None.