TABLE 2.

Comparison of cardiorespiratory measurements between time-points, intervention and sleep stage

	eAT		WWSC		p-value#
	Baseline	Follow-up	Baseline	Follow-up	Time-point	Intervention	Intervention × time-point	Sleep stage	Intervention × sleep stage
Subjects	194			181
Respiratory rate cycles per min
N2	17.24±2.75	18.60±2.46	17.18±2.58	17.52±2.68	<0.001	0.01	0.02	<0.001	0.4+
N3	18.08±2.62	19.29±2.56	18.0±2.71	18.53±3.03
REM	19.08±2.80	20.23±2.66	19.24±2.81	19.42±3.22
RSA¶
N2	1.93±0.32	1.86±0.2	1.95±0.27	1.95±0.27	0.4+	0.06	0.05	<0.001	0.5+
N3	1.90±0.35	1.81±0.29	1.90±0.30	1.91±0.28
REM	1.67±0.34	1.59±0.32	1.66±0.32	1.67±0.31
Heart rate beats per min
N2	80.8±9.9	79.7±9.3	80.6±9.3	79.4±8.4	0.06+	0.5+	0.8+	<0.001	0.4+
N3	83.7±10.4	82.7±9.9	83.8±9.8	82.6±8.8
REM	85.2±9.0	83.6±8.0	84.9±8.9	83.5±8.5

Data are presented as mean±sd, unless otherwise stated. eAT: early adenotonsillectomy; WWSC: watchful waiting with supportive care; REM: rapid eye movement; RSA: respiratory sinus arrhythmia; N2: stage 2 non-REM; N3:stage 3 non-REM. ^#: obtained using three-way ANCOVA adjusted for likely confounding factors of age (5–7 years of age versus 8–9 years of age), race (black versus other), body mass index z-score, body mass index z-score change and sex; ^¶: reported and analysed as log-transformed values; ⁺: nonsignificant.