Nocturnal oximetry parameters as predictors of sleep apnea severity in resource‐limited settings

Abstract

Nocturnal oximetry is an alternative modality for evaluating obstructive sleep apnea syndrome (OSAS) severity when polysomnography is not available. The Oxygen Desaturation (≥3%) Index (ODI3) and McGill Oximetry Score (MOS) are used as predictors of moderate-to-severe OSAS (apnea-hypopnea index-AHI >5 episodes/h), an indication for adenotonsillectomy. We hypothesised that ODI3 is a better predictive parameter for AHI >5 episodes/h than the MOS. All polysomnograms performed in otherwise healthy, snoring children with tonsillar hypertrophy in a tertiary hospital (November 2014 to May 2019) were analysed. The ODI3 and MOS were derived from the oximetry channel of each polysomnogram. Logistic regression was applied to assess associations of ODI3 or MOS (predictors) with an AHI >5 episodes/h (primary outcome). Receiver operating characteristic (ROC) curves and areas under ROC curves were used to compare the ODI3 and MOS as predictors of moderate-tosevere OSAS. The optimal cut-off value for each oximetry parameter was determined using Youden's index. Polysomnograms of 112 children (median [interquartile range] age 6.1 [3.9-9.1] years; 35.7% overweight) were analysed. Moderate-to-severe OSAS prevalence was 49.1%. The ODI3 and MOS were significant predictors of moderate-to-severe OSAS after adjustment for overweight, sex, and age (odds ratio[OR] 1.34, 95% confidence interval [CI] 1.19-1.51); and OR 4.10, 95% CI 2.06-8.15, respectively; p < 0.001 for both). Area under the ROC curve was higher for the ODI3 than for MOS (0.903 [95% CI 0.842-0.964] versus 0.745 [95% CI 0.668-0.821]; p < 0.001). Optimal cut-off values for the ODI3 and MOS were ≥4.3 episodes/h and ≥2, respectively. The ODI3 emerges as preferable or at least a complementary oximetry parameter to MOS for detecting moderate-to-severe OSAS in snoring children when polysomnography is not available.

Novel Indices to Improve the Diagnostic Ability of Nocturnal Oximetry in Children with OSAS

“…However, the ODI3 was falsely negative in one participant before adenotonsillectomy and falsely positive (i.e., >3.6) in four children (8.9%) after the operation. Although lower than those reported in studies focusing on moderate-to-severe OSAS [ 18 , 26 ], these figures highlight the risk of misclassification when ODI3 is applied as the sole predictor.…”

“…The MOS, which relies on the identification of desaturation clusters (i.e., repeated events of SpO 2 drop by ≥4% from the baseline within a period of 10–30 min), represents the most popular OSAS-related outcome [ 1 ]. A positive score (i.e., MOS ≥ 2) performs excellent in identifying children with moderate-to-severe OSAS, but its false negative rate is high [ 16 ]; in a previous study [ 14 ], 36.2% of children with inconclusive MOS (MOS = 1) had an AHI of >5 events per hour, while 41.8% of those with AHI >5 had an inconclusive MOS in a more recent report [ 26 ]. In our study, the inconclusive MOS rate before adenotonsillectomy was 37.8% ( Table 1 ), thus, confirming that MOS per se may lead to the significant misclassification of children with moderate-to-severe OSAS as having mild or even no disease [ 16 ].…”

A Review of Novel Oximetry Parameters for the Prediction of Cardiovascular Disease in Obstructive Sleep Apnoea

“…Although ODI and AHI both measure event rates, ODI performs better in predicting adverse CVD outcomes [30,31]. ODI measures the number of transient desaturation events from a baseline value and divided by the hours of sleep.…”

“…ODI measures the number of transient desaturation events from a baseline value and divided by the hours of sleep. The American Academy of Sleep Medicine (AASM) does not specify the criteria for scoring desaturation events [31][32][33][34][35], and hence a range of methods have been used to calculate ODI. Some studies define ODI as the rate of oxygen desaturation events occurring when SpO 2 drops lower than the desaturation threshold from the average saturation in the previous 120 s and persists for at least 10 s [36,37].…”