Multi-level linear mixed models reveal the relationship between COVID-19 phases and physiological parameters
| Predictors | Respiratory rate | Heart rate | Heart rate variability (SDNN) | Heart rate variability (RMSSD) | Heart rate variability ratio | Wrist skin temperature | Skin perfusion |
| Intercept | 15.10† (0.26) | 55.43† (0.83) | 59.64† (1.43) | 43.71† (1.16) | 0.50† (0.02) | 35.32† (0.06) | −0.01† (0.00) |
| COVID-19 phase | |||||||
| Baseline | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group |
| Incubation | 0.02 (0.06) | 0.87† (0.29) | −1.48* (0.59) | −0.37 (0.48) | −0.01* (0.01) | 0.13† (0.04) | 0.00 (0.00) |
| Presymptomatic | 0.14 (0.12) | 1.00† (0.36) | −1.70* (0.64) | −0.75 (0.53) | −0.02* (0.01) | 0.18† (0.05) | 0.00 (0.00) |
| Symptomatic | 1.00† (0.18) | 2.15† (0.48) | −1.45* (0.73) | 0.12 (0.51) | 0.00 (0.01) | 0.30† (0.05) | 0.00 (0.00) |
| Recovery | 0.10 (0.06) | 0.87† (0.22) | −0.92 (0.51) | 0.04 (0.44) | 0.00 (0.01) | 0.20† (0.03) | 0.00 (0.00) |
Unstandardised β -coefficient values reported, with SEs in brackets.
*P<0.05.
†0.007, respectively, with Bonferroni correction.
RMSSD, root mean square of successive differences; SDNN, SD of the normal-to-normal interval.