. 2022 Feb 15;24(2):e28890. doi: 10.2196/28890

Table 2.

Comparison of accuracy (RMSE^a) and bias in SpO₂^b estimation between different motion tasks, for each device, for 33 participants.

Performance metrics		At rest	STS^c	Rubbing	Tapping	Drinking	Turning pages	Tablet use	P value^d
AP20
	Available SpO₂ points, n	32	30	32	30	31	27	31	N/A^e
	RMSE, % (95% CI)	0.82 (0.55-1.06)	4.68 (1.47-7.72)	11.96 (9.44-14.23)	12.21 (9.31-14.74)	1.96 (1.48-2.46)	8.52 (6.18-10.75)	8.01 (1.15-13.72)	N/A
	Mean bias, %	–0.21^f,g	–0.9^h,i	–9.91^f,g,j,k	–9.82^g,i	–1.45^j	–6.46	–2.22^k	<.001
	Mean \|bias\|, %	0.6^k,l,m	2.15^f,g	9.91^f,i,j,k	9.85^g,h,l,n	1.57^h,j	6.46^m	2.56^i,n	<.001
	Precision, %	0.81^f	4.31^h	6.91	7.49^f,h,j,k	1.37^j	5.57	7.89^k	<.001
CheckMe O2+
	Available SpO₂ points, n	30	31	31	30	32	32	32	N/A
	RMSE, % (95% CI)	1.68 (1.21-2.12)	3.5 (1.49-5.37)	8.45 (5.86-10.88)	3.99 (2.28-5.69)	2.43 (1.9-2.96)	7.83 (5.9-9.8)	4.2 (2.86-5.47)	N/A
	Mean bias, %	–1.06	–1.37	–6.19^j	–2.65^h,j	–1.93	–6.04^h	–2.94	.001
	Mean \|bias\|, %	1.29	1.92	6.31	2.71	1.97	6.06	2.98	.005
	Precision, %	1.33	3.08	5.84	3.06	1.41	5.11	2.86	.13
Philips MX450
	Available SpO₂ points, n	33	33	33	32	32	32	32	N/A
	RMSE, % (95% CI)	1.11 (0.92-1.28)	2.31 (1.9-2.67)	9.49 (7.04-11.86)	7.15 (3.07-10.3)	1.17 (1.0-1.36)	6.64 (3.81-9.03)	1.97 (1.29-2.68)	N/A
	Mean bias, %	0.89^f	1.97^h	–5.37^f,h,i,j,k	–1.75ⁱ	0.84^j	–3.04	0.4^k	<.001
	Mean \|bias\|, %	0.97^h	2.02	6.6^h,j	3.33	1.06^j	4.03	1.51	.002
	Precision, %	0.63^g,k	0.78^f	6.77^f,i,j,k	7.16^g,h	0.8^h,j	6.04	1.82ⁱ	<.001
WristOx2 3150
	Available SpO₂ points, n	32	33	29	29	32	24	33	N/A
	RMSE, % (95% CI)	1.18 (0.84-1.51)	2.33 (1.26-3.41)	9.5 (7.29-11.5)	7.17 (4.66-9.35)	1.27 (0.95-1.57)	6.28 (4.25-8.27)	3.91 (1.49-5.62)	N/A
	Mean bias, %	–0.71^f	–0.4^h	–7.52^f,h,i,j,k	–4.56ⁱ	–0.86^j	–4.51	–1.81^k	.002
	Mean \|bias\|, %	0.92^k,l	1.38^f,g	7.52^f,i,j,k	4.69^g,l,m	1.02^h,j	4.56	2.02^h,m	<.001
	Precision, %	0.97^f	2.12^h	5.98	5.7^f,h,j,k	0.93^j	4.35	3.06^k	.001

^aRMSE: root-mean-square error.

^bSpO₂: peripheral oxygen saturation.

^cSTS: sit-to-stand.

^dOne-way ANOVA followed by the Tukey-Kramer test was used to evaluate differences in the mean bias and mean absolute bias between tasks. The Levene test was used in the case of precision.

^eN/A: not applicable.

^f-nDifferent from each other; for example, for CheckMe O2+, the mean bias of the tapping motion task was different from that of the turning page task and that of the rubbing task (paired differences coded as ^j and ^h, respectively).