Comparison of a Commercial Accelerometer with Polysomnography and Actigraphy in Children and Adolescents.

STUDY OBJECTIVES: To evaluate the reliability and validity of the commercially available Fitbit Ultra (2012) accelerometer compared to polysomnography (PSG) and two different actigraphs in a pediatric sample. DESIGN AND SETTING: All subjects wore the Fitbit Ultra while undergoing overnight clinical polysomnography in a sleep laboratory; a randomly selected subset of participants also wore either the Ambulatory Monitoring Inc. Motionlogger Sleep Watch (AMI) or Phillips-Respironics Mini-Mitter Spectrum (PRMM). PARTICIPANTS: 63 youth (32 females, 31 males), ages 3-17 years (mean 9.7 years, SD 4.6 years). MEASUREMENTS: Both "Normal" and "Sensitive" sleep-recording Fitbit Ultra modes were examined. Outcome variables included total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE). Primary analyses examined the differences between Fitbit Ultra and PSG using repeated-measures ANCOVA, with epoch-by-epoch comparisons between Fitbit Ultra and PSG used to determine sensitivity, specificity, and accuracy. Intra-device reliability, differences between Fitbit Ultra and actigraphy, and differences by both developmental age group and sleep disordered breathing (SDB) status were also examined. RESULTS: Compared to PSG, the Normal Fitbit Ultra mode demonstrated good sensitivity (0.86) and accuracy (0.84), but poor specificity (0.52); conversely, the Sensitive Fitbit Ultra mode demonstrated adequate specificity (0.79), but inadequate sensitivity (0.70) and accuracy (0.71). Compared to PSG, the Fitbit Ultra significantly overestimated TST (41 min) and SE (8%) in Normal mode, and underestimated TST (105 min) and SE (21%) in Sensitive mode. Similar differences were found between Fitbit Ultra (both modes) and both brands of actigraphs. CONCLUSIONS: Despite its low cost and ease of use for consumers, neither sleep-recording mode of the Fitbit Ultra accelerometer provided clinically comparable results to PSG. Further, pediatric sleep researchers and clinicians should be cautious about substituting these devices for validated actigraphs, with a significant risk of either overestimating or underestimating outcome data including total sleep time and sleep efficiency.

Respiratory and polysomnographic values in 3- to 5-year-old normal children at higher altitude.

STUDY OBJECTIVES: To determine polysomnographic parameter differences in children living at higher altitude to children living near sea level. DESIGN AND SETTING: Prospective study of non-snoring, normal children recruited from various communities around Denver, CO. In-lab, overnight polysomnograms were performed at a tertiary care children's hospital. All children required residence for greater than one year at an elevation around 1,600 meters. PARTICIPANTS: 45 children (62% female), aged 3-5 years, 88.9% non-Hispanic white with average BMI percentile for age of 47.8% ± 30.7%. MEASUREMENTS AND RESULTS: Standard sleep indices were obtained and compared to previously published normative values in a similar population living near sea level (SLG). In the altitude group (AG), the apnea-hypopnea index was 1.8 ± 1.2 and the central apnea-hypopnea index was 1.7 ± 1.1, as compared to 0.9 ± 0.8 and 0.8 ± 0.7, respectively, (P ≤ 0.005) in SLG. Mean end-tidal CO2 level in AG was 42.3 ± 3.0 mm Hg and 40.6 ± 4.6 mm Hg in SLG (P = 0.049). The ≥ 4% desaturation index was 3.9 ± 2.0 in AG compared to 0.3 ± 0.4 in SLG (P < 0.001). Mean periodic limb movement in series index was 10.1 ± 12.3 in AG and 3.6 ± 5.4 in SLG (P = 0.001). CONCLUSION: Comparison of altitude and sea level sleep studies in healthy children reveals significant differences in central apnea, apneahypopnea, desaturation, and periodic limb movement in series indices. Clinical providers should be aware of these differences when interpreting sleep studies and incorporate altitude-adjusted normative values in therapeutic-decision making algorithms.

Persistence of obstructive sleep apnea syndrome in children after adenotonsillectomy.

OBJECTIVE: To investigate the relative contribution of various risk factors to the surgical outcome of adenotonsillectomy for obstructive sleep apnea syndrome in children. STUDY DESIGN: Children (n = 110; mean age, 6.4 +/- 3.9 years) underwent two polysomnographic evaluations before and after adenotonsillectomy. In addition, 22 control children were studied. History for allergy and family history of sleep-disordered breathing was taken before each polysomnographic evaluation. RESULTS: Significant changes in sleep stage percentages and sleep fragmentation were found in the postsurgery study compared with the presurgery study; 25% of the children had apnea/hypopnea index (AHI) 1 and <5, and 29% had AHI >/=5 in the postsurgery study. The frequency of subjects with AHI