. 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 4.

Model equation, R² and NMAE for regressions predicting PROMIS Physical Function, Pain Interference, and Average Pain Intensity scores from Roland-Morris Disability Questionnaire in PROMIS 1 W2 and ACT samples individually and combined.

PROMIS Score	Sample	Equation	R²	NMAE
Physical Function	PROMIS I W2 (n=179)	45.928 – 0.640 x RMDQ total score	0.37	0.69
	ACT (n=384)	51.928 – 0.869 x RMDQ total score	0.48	0.57
	ACT+PROMIS 1 W2 (n=563)	51.063 – 0.879 x RMDQ total score	0.50	0.62
Pain Interference	PROMIS I W2 (n=179)	54.762 + 0.707 x RMDQ total score	0.37	0.69
	ACT (n=384)	51.814 + 0.784 x RMDQ total score	0.45	0.64
	ACT+PROMIS 1 W2 (n=563)	52.154 + 0.811 x RMDQ total score	0.47	0.62
Average Pain	PROMIS I W2 (n=179)	4.746 + 0.129 x RMDQ total score	0.13	0.87
Intensity	ACT (n=384)	3.449 + 0.126 x RMDQ total score	0.13	0.89
	ACT+PROMIS 1 W2 (n=563)	3.510 + 0.161 x RMDQ total score	0.20	0.83

NOTE: NMAE = Normalized Mean Absolute Error; PROMIS I W2 = PROMIS 1 Wave 2 Pain and Depression study; ACT= Assessment of Chiropractic Treatment for Low Back Pain and Smoking Cessation in Military Active Duty Personnel. R² and NMAE are adjusted using linear equating to address regression to the mean.