Clinical utility of oximetric parameters to identify a high-risk phenotype of moderate-severe Obstructive Sleep Apnea...

It is unclear if oximetric parameters, such as total time of SpO₂  < 90%, (T90), oxygen desaturation index-3% (ODI), minimum SpO₂ , are able to describe a high-risk subtype of cardiovascular (CV) comorbidities in patients with Obstructive sleep apnea (OSA) beyond the apnea-hypopnea index.

To analyzed oximetric variables in patients with moderate-severe OSA to assess their predictive value regarding as hypertension, type 2 diabetes mellitus (T2DM), coronary heart disease (CHD) and CV mortality.

Using data from SantOSA cohort, we develop receiver operating characteristic curve and area under the curve (AUC) for each parameter, defining the proposed cutoff point in a training set. Then, in a validation set with a 5 years follow-up, we evaluate the clinical differences between groups using the proposed cutoff. We also calculated adjusted Hazard Ratios (HR) of mortality using a Cox regression model.

About 965 patients with moderate-severe OSA (525 in training and 440 in validation group) were included. The best AUC was achieved with T90 (AUC = 0.66) and ODI (AUC = 0.61). Proposed cutoffs of T90 were hypertension: 10%, T2DM: 20%, CHD: 15%, meanwhile, proposed cutoff of ODI was ≥ 30 ev for hypertension and T2DM. Regarding CV mortality, T90 ≥ 20% was independently associated with an adjusted HR 2.44 (CI, 1.21-4.94), P-value = 0.01, meanwhile, ODI ≥ 30 ev. reported and adjusted HR 1.59 (CI, 0.75-3.39), P-value = 0.22.

In patients with moderate-severe OSA, oximetric parameters, especially T90 ≥ 20% remained a predictor of mortality after adjusting for a range of demographic and disease predictors.