Morbidity cut-offs for sleep apnea and periodic leg movements in predicting subjective complaints in seniors.

Despite its widespread use, the validity of the 5/h morbidity cut-off for the Respiratory Disturbance Index (RDI) or the Movement Index (MI) in determining presence of sleep apnea (SA) or sleep-related periodic leg movements (PLMs), respectively, has not been determined for any aged population. One hundred community resident seniors 60 years of age or older underwent three consecutive nights of polysomnography and also completed conventional measures of subjective sleep-wake complaints (written sleep questionnaire, sleep log, sleep interview) and mood disturbances (Zung Self-Rating Depression and Anxiety Scales, Profile of Mood States, Beck Depression Inventory). Based on the 5/h cut-off, 34% had SA and 58% had PLMs. Despite this, the frequency of subjective sleep-wake and mood disturbance was low across methods of assessment. Groups formed by the 5/h cut-off for RDI or MI failed to differ significantly in responses on all subjective sleep-wake and mood measures. Higher cut-offs also were examined and proved weak or ineffective in predicting subjective sleep-wake and mood disturbance. Preliminary investigations suggested that alternative measures of severity of SA (means oxygen desaturation and means duration of apneas or hypopneas) may be better predictors of subjective disturbance than RDI in this population. These findings both (a) demonstrate that the polygraphically identified SA and PLMs which are widespread in seniors tend not to be manifested in self-reported sleep-wake or mood disturbance, and (b) illustrate the need for validated morbidity cut-offs for SA and PLMs.