1162 VALIDATION OF AMBULATORY ACTIVITY MONITORS FOR SLEEP MEASUREMENT IN HUNTINGTON’S DISEASE GENE CARRIERS

Introduction:Sleep disturbance is one of the earliest symptoms of Huntington’s disease (HD), starting up to 10 years prior to diagnosis, and might have an influence on the speed of neurodegeneration and other symptoms. Elucidation of the etiology and the progression of these problems requires longitudinal study designs, which are hampered by the absence of a valid ambulatory objective sleep measurement tool in HD.Methods:Sleep of seven Huntington’s gene carriers (age=54 ± 6.4, 1M) was simultaneously assessed using polysomnography (PSG), actigraphy (Actiwatch Spectrum Pro) and Jawbone UP2 (JB) during an overnight laboratory sleep study. The ambulatory activity monitors were compared to PSG on the measurement of total sleep time (TST), sleep efficiency (SE), sleep latency (SL) and wake after sleep onset (WASO). Epoch-by-epoch comparisons determined sensitivity, specificity, accuracy, and agreement using prevalence and bias adjusted kappa (PABAK).Results:Compared to PSG, actigraphy and JB overestimated TST by 74.0 ± 54.4min and 78.7 ± 51.2min, and SE by 14.8 ± 11.0% and 16.3 ± 10.1%, respectively. Similarly, the monitors underestimated SL by 23.0 ± 26.4min and 19.3 ± 28.8min, and WASO by 20.0 ± 32.2min and 36.0 ± 28.2min, respectively. These differences were significant for TST and SE for both monitors, and for WASO for JB. Actigraphy and JB showed high sensitivity (0.97, 0.99), low specificity (0.31, 0.34), good accuracy (0.80, 0.83), and substantial agreement (PABAK = 0.62, 0.65).Conclusion:In assessing sleep in HD gene carriers, both ambulatory monitors showed good ability to recognize sleep, but poor ability to identify wake. Substantial agreement between PSG and the monitors indicates a possible skew in the sensitivity and specificity values due to the high prevalence of sleep overnight. While unfit to replace PSG, actigraphy and JB might still be suitable for longitudinal research in HD, providing investigators are aware of the inaccuracies in the measurement of sleep indices. Clinical utility with circadian rhythm disorders remains to be tested.Support (If Any):