Introduction: Polysomnography is the gold standard test to diagnose obstructive sleep apnea (OSA). The two common polysomnography available: home sleep apnea test (HSAT) or full attended polysomnography. Full attended polysomnography, gold standard test, is an expensive test and has a long waiting list. HSAT is cheap and sensitive, but it has the main limitation of respiratory effort-related arousal (RERA) detection. The presence of RERA results in a higher respiratory disturbance index (RDI) than apnea–hyponea index (AHI). Knowing factors associated with higher RDI than AHI in patients with OSA may reduce numbers of patients required full attended polysomnography which lower cost for OSA diagnosis. This study aimed to evaluate factors associated with higher RDI than AHI in patients with OSA.
Methods: This was a retrospective analytical study. The inclusion criteria were adult patients with OSA and diagnosed with OSA by full attended polysomnography. Clinical factors and polysomnography were collected from the hospital database. Factors associated with higher RDI than AHI were detected by multivariable logistic regression analysis.
Results: There were 72 patients with OSA met the study criteria. Of those, 27 patients (37.50%) had a higher RDI than AHI. There were five factors in the predictive model for higher RDI than AHI including age, sex, hypertension, diabetes, and body mass index. Only body mass index was independently associated with higher RDI than AHI. An adjusted odds ratio of body mass index was 1.10 (95% confidence interval of 1.01, 1.19). A body mass index of 26.03 kg/m2 had a sensitivity of 81.48% and specificity of 33.33% in order to detect higher RDI than AHI.
Conclusions: Patients who are suspected for OSA with the body mass index of 26.03 kg/m2 may have higher RDI than AHI. These patients may be required full attended polysomnography, while other patients may be tested with HSAT which may report comparable AHI values.
