. Author manuscript; available in PMC: 2022 Jul 1.

Published in final edited form as: Arch Phys Med Rehabil. 2021 Mar 5;102(7):1317–1323. doi: 10.1016/j.apmr.2021.02.014

Table 3.

Model equation, R² and NMAE for regressions predicting PROMIS Physical Function, Pain Interference, and Average Pain Intensity scores from Oswestry Disability Index for the PROMIS I W2 and CERC samples, individually and combined.

PROMIS Score	Sample	Equation	R²	NMAE
Physical Function	PROMIS I W2 (n=212)	46.762 – 0.249 x ODI total score	0.47	0.63
	CERC (n=1527)	53.622 – 0.401 x ODI total score	0.51	0.60
	CERC+PROMIS 1 W2 (n=1739)	53.216 – 0.389 x ODI total score	0.55	0.58
Pain Interference	PROMIS I W2 (n=212)	52.957 + 0.301 x ODI total score	0.55	0.57
	CERC (n=1527)	46.865 + 0.403 x ODI total score	0.50	0.62
	CERC+PROMIS 1 W2 (n=1739)	47.019 + 0.408 x ODI total score	0.56	0.57
Pain Intensity	PROMIS I W2 (n=212)	4.133 + 0.062 x ODI total score	0.26	0.75
	CERC (n=1674)	1.932 + 0.095 x ODI total score	0.35	0.70
	CERC+PROMIS 1 W2 (n=1886)	1.959 + 0.099 x ODI total score	0.41	0.66

NMAE = Normalized Mean Absolute Error; CERC= CERC= Center for Excellence in Research for Complementary and Integrative Health; PROMIS I W2 = PROMIS 1 Wave 2 Pain and Depression study. R² and NMAE are adjusted using linear equating to address regression to the mean.