A memory stores R-R interval (RRI) data collected from a patient over a time interval and oxygen saturation (SaO2) data collected from the patient over the time interval. A processor is programmed to analyze the SaO2 data to identify desaturation events, analyze the RRI data to identify dips, utilize the dips to construct a RRI dip index measure of RRI dips per unit time over the time interval, determine a number of desaturations above a predefined threshold, determine an oxygen desaturation index (ODI), and utilize the RRI dip index and the ODI to provide results indicative of a risk of sleep-disordered breathing (SDB) for the patient.
