Oxygen desaturation index, lowest arterial oxygen saturation and time spent below 90% oxygen saturation as diagnostic markers for obstructive sleep apnea

Obstructive sleep apnea (OSA) syndrome is associated with a high mortality, and blood oxygen indexes play an important role in evaluating this disease. The objective of this study was to explore the value of blood oxygen indexes, including minimum oxygen saturation (LSpO ), oxygen reduction index (ODI) and time spent with oxygen saturation below 90% (TS 90%), as diagnostic markers for OSA syndrome. In this retrospective study, 320 patients with OSA treated in Ningbo First Hospital from June 2018 to June 2021 were included and divided into mild, moderate, and severe groups according to the severity of the condition (n = 104, 92, and 124, respectively). The blood oxygen indexes as well as the apnea-hypopnea index (AHI) were compared. The Spearman correlation analysis was performed to explore the relationship between the parameters. Receiver operating characteristic curves were generated to evaluate the diagnostic value of the blood oxygen indexes for OSA syndrome. There were significant differences in body weight, body mass index, and blood pressure before and after sleep among the groups (P < 0.05). LSpO levels followed a pattern with the severe group showing the lowest values, followed by the moderate group, and then the mild group, whereas ODI and TS 90% levels showed the opposite (P < 0.05). Spearman correlation analysis showed that AHI, ODI, TS 90% were positively correlated with severity of OSA, whereas LSpO was negatively correlated with severity of OSA. ODI showed a high diagnostic value for OSA (area under curve (AUC) = 0.823, 95% CI: 0.730-0.917). TS 90% showed a high diagnostic value for OSA (AUC = 0.872, 95% CI: 0.794-0.950). LSpO showed high accuracy in diagnostic value for OSA (AUC = 0.716, 95% CI: 0.596-0.835). The combination of the 3 indexes demonstrated a high diagnostic value for OSA (AUC = 0.939, 95% CI: 0.890-0.989). The diagnostic value of the combined signature was found to be significantly higher compared to the value of individual indexes (P < 0.05). The evaluation of the severity of OSA should not rely solely on a single observation index, but rather on a combination of ODI, LSpO and TS 90%. This combined diagnostic signature can provide a more comprehensive assessment of the patient's condition and serve as an alternative diagnostic basis to ensure timely diagnosis and appropriate clinical treatment for OSA.