Factors associated with respiratory disturbance index higher than apnea-hypopnea index in patients with obstructive sleep apnea.

Abstract

Polysomnography, used for diagnosing obstructive sleep apnea (OSA), is commonly available with a home sleep apnea test (HSAT) and in-laboratory polysomnography. In-laboratory polysomnography, the gold standard test, is expensive and has a long waitlist, whereas HSATs are inexpensive and sensitive but may not adequately detect respiratory effort-related arousal (RERA), the presence of which results in a higher respiratory disturbance index (RDI) than the apnea-hypopnea index (AHI) and may indicate more severe OSA. In certain patients, identifying factors associated with a higher RDI than AHI may decrease the need for full polysomnography. The present retrospective analytical study of adult patients with OSA diagnosed by in-laboratory polysomnography aimed to evaluate factors associated with a higher RDI than AHI. Factors associated with a higher RDI than AHI were computed via multivariable logistic regression analysis. Of 72 patients with OSA, 27 (37.50%) had an RDI higher than AHI. There were five factors in the predictive model for RDI higher than AHI: Age, sex, hypertension, diabetes, body mass index (BMI) and snoring, tired, observed apnea, high blood pressure, body mass index, age, neck circumference, and gender score. Only BMI was independently associated with a higher RDI than AHI [adjusted odds ratio, 1.10 (95% confidence interval: 1.01, 1.19)] and a BMI of 26.03 kg/m² had a sensitivity of 81.48% and a specificity of 33.33% in detecting higher RDI than AHI. The receiver operating characteristic (ROC) curve of BMI for RDI higher than AHI was 60.66% (95% confidence interval: 46.53%, 74.78%). Although the area under the ROC curve had modest predictive ability, patients with suspected OSA with a BMI of 26.03 kg/m² may require in-laboratory polysomnography, whereas other patients may be tested via HSAT.