Table 3.

Determinants of the absolute bias levels.

Models	Variables	Univariate		Multivariate model 1		Multivariate model 2a
		Estimate (95% CI)	p-value	Estimate (95% CI)	p-value	Estimate (95% CI)	p-value
Absolute bias of RR	Posture supine vs. sitting	0.104 (0.039 to 0.168)	0.002	0.186 (0.122 to 0.251)	< 0.001	0.103 (0.039 to 0.168)	0.002
	age < 50 vs. ≥ 50 years	0.115 (− 0.241 to 0.472)	0.529	0.130 (− 0.261 to 0.521)	0.515	0.189 (− 0.211 to 0.589)	0.371
	Sex M vs. F	0.056 (− 0.266 to 0.377)	0.736	− 0.071 (− 0.399 to 0.257)	0.671	0.036 (− 0.300 to 0.371)	0.839
	BMI (kg/m2)	− 0.015 (− 0.055 to 0.025)	0.468	− 0.004 (− 0.047 to 0.038)	0.837	− 0.024 (− 0.067 to 0.019)	0.290
	RR < 18 breath/min	0.809 (0.700 to 0.918)	< 0.001	0.864 (0.753 to 0.974)	< 0.001	–	–
Absolute bias of HR	Posture supine vs. sitting	0.158 (− 0.073 to 0.389)	0.181	0.308 (0.063 to 0.553)	0.014	0.157 (− 0.073 to 0.389)	0.181
	age < 50 vs. ≥ 50 years	3.201 (0.983 to 5.419)	0.007	0.051 (− 0.031 to 0.132)	0.229	0.056 (− 0.027 to 0.134)	0.180
	Sex M vs. F	1.800 (− 0.291 to 3.891)	0.098	1.429 (− 0.702 to 3.559)	0.195	1.588 (− 0.459 to 3.635)	0.144
	BMI (kg/m2)	0.225 (− 0.036 to 0.485)	0.098	0.102 (− 0.196 to 0.400)	0.506	0.095 (− 0.192 to 0.382)	0.528
	HR < 70 bpm	0.932 (0.493 to 1.371)	< 0.001	1.074 (0.616 to 1.532)	< 0.001	–	–
	≥ 80 bpm	0.316 (− 0.282 to 0.914)	0.301	0.223 (− 0.385 to 0.831)	0.472	–	–

Linear mixed effect models were performed with individuals as the random term were used to estimate the effects of the factors.

BMI body mass index, M male, F female, HR heart rate, RR respiratory rate.

^aMultivariate model 2 = multivariate model 1 minus RR (or HR).