Correlation between Desaturation Event Index and Apnea Hypopnea Index for Diagnosis of Obstructive Sleep Apnea

Abstract

Objective: To determine if there is a correlation between desaturation-event index (DEI) and apnea-hypopnea index (AHI) which may potentially facilitate screening and earlier diagnosis of obstructive sleep apnea (OSA).

 Methods: A retrospective chart review was conducted to compare patients who underwent high-resolution pulse oximetry (HRPO) during in a sleep medicine consult while inpatient, followed by outpatient polysomnography (PSG) after their discharge over a 2-year period at a tertiary care academic center. Demographic data, DEI, AHI, and oxygen nadir levels were collected.

 Results: Sixty-six patients (46 males, 20 females; mean age of 59.1 years) with suspected OSA underwent inpatient HRPO during their hospital stay, followed by a PSG in the outpatient setting. The strength of association between DEI and AHI was determined using a Spearman’s rank correlation coefficient, which showed a statistically significant, moderately weak positive association between DEI and AHI (ρ=0.317, p=0.009). Multivariable analysis demonstrated a predictive value of 0.270 between AHI and DEI, when adjusted for age, sex, body mass index (BMI), ethnicity, reason of admission, medical comorbidities, and usage of supplemental oxygen (p=0.040). HRPO nadir oxygen saturation (NOS) also correlated with PSG NOS with a Spearman’s Rho correlation coefficient of 0.320 (p=0.013). Multivariable analysis showed a predictive value beta of 0.316 (p=0.033).

 Conclusion: DEI calculated through HRPO may be correlated with AHI. Although there is a correlation, HRPO should not replace PSG. Instead, HRPO should be used for screening purposes to help identify people in need of further workup.