Table 1

Objective feature distribution for admitted and non-admitted children

FeatureAdmission required N=616 (30.0%)Admission not required N=1435 (70.0%)p ValueOR (95% CI)
Pulse rate variability analysis*
 Heart rate (bpm)140 (126–154)125 (112–138)<0.0011.03 (1.02 to 1.03)
 RR (s)0.43 (0.39–0.47)0.48 (0.43–0.53)<0.0010.49 (0.42 to 0.57)†
 SDNN (s)0.016 (0.011–0.025)0.022 (0.014–0.037)<0.0010.83 (0.78 to 0.89)‡
 RMSSD (s)0.016 (0.013–0.025)0.021 (0.015–0.039)<0.0010.91 (0.87 to 0.95)‡
 SD1 (s)0.012 (0.093–0.018)0.015 (0.011–0.027)<0.0010.99 (0.98 to 0.99)‡
 SD2 (s)0.018 (0.011–0.029)0.026 (0.016–0.043)<0.0010.98 (0.98 to 0.99)‡
 LFn (nu)0.37 (0.2–0.57)0.38 (0.23–0.55)0.0030.93 (0.89 to 0.98)‡
 HFn (nu)0.14 (0.09–0.24)0.18 (0.12–0.27)<0.0010.86 (0.79 to 0.94)
 LF/HF (ratio)2.3 (1.1–4.7)2 (0.95–3.9)0.21.00 (0.99 to 1.00)
SpO2 analysis
 SpO2median (%)96 (91–98)98 (97–99)<0.0010.79 (0.76 to 0.81)
 SpO2std (%)0.73 (0.51–1.2)0.54 (0.4–0.83)<0.0010.54 (0.4 to 0.83)
 SpO2delta (%)0.31 (0.19–0.48)0.22 (0.13–0.34)<0.0013.5 (2.5 to 4.8)
 tb98 (s)39 (11–56)3.3 (0–34)<0.0011.4 (1.3 to 1.4)§
 tb96 (s)26 (0–53)0 (0–3.2)<0.0011.4 (1.3 to 1.5)§
 tb94 (s)2 (0–41)0 (0–0.33)<0.0011.5 (1.4 to 1.6)§
 nb1 (# times)4 (1–8)1 (0–4.5)<0.0011.1 (1.08 to 1.12)
 nb2 (# times)0 (0–3)0 (0–1)<0.0011.1 (1.1 to 1.2)
 nb3 (# times)0 (0–1)0 (0–0)<0.0011.1 (1.1 to 1.2)
Non-pulse oximetry data
 Heart rate age z-score0.66 (−0.19 to 1.7)0.23 (−0.58 to 1.1)<0.0011.3 (1.2 to 1.4)
 Respiratory rate age z-score0.47 (−0.48 to 1.9)−0.046 (−0.8 to 1.1)<0.0011.2 (1.1 to 1.3)
 Age (days)230 (70.5–542)477 (202–1038)<0.0010.989 (0.987 to 0.991)§
 Gender (% of male)67%59%<0.0011.43 (1.17 to 1.74) (male vs female)
  • Values include feature medians (quartiles), p value and OR (95% CI).

  • *Adjusted for age.

  • †Associated with an increase of 0.1 times the feature unit.

  • ‡Associated with an increase of 0.01 times the feature unit.

  • §Associated with an increase of 10 times the feature unit.

  • HFn, high frequency normalised; LFn, low frequency normalised; RMSSD, root mean square of the successive differences; RR, respiratory rate; SpO2, blood oxygen saturation.