Table 4.

Correlation between PROMs

	Number of observations (n)	Pearson correlation coefficient (r)	Strength of correlation	p Value
NDI and PROMIS-PF
Preoperatively	106	−0.565	Moderate	<0.0001
2 weeks	94	−0.600	Moderate	<0.0001
6 weeks	82	−0.598	Moderate	<0.0001
3 months	76	−0.689	Strong	<0.0001
6 months	60	−0.622	Strong	<0.0001
1 year	35	−0.705	Strong	<0.0001
SF-12 PHS and NDI
Preoperatively	117	−0.551	Moderate	<0.0001
2 weeks	111	−0.709	Strong	<0.0001
6 weeks	97	−0.566	Moderate	<0.0001
3 months	91	−0.678	Strong	<0.0001
6 months	73	−0.679	Strong	<0.0001
1 year	41	−0.749	Strong	<0.0001
SF-12 PHS and PROMIS-PF
Preoperatively	105	0.687	Strong	<0.0001
2 weeks	93	0.570	Moderate	<0.0001
6 weeks	80	0.729	Strong	<0.0001
3 months	73	0.729	Strong	<0.0001
6 months	60	0.644	Strong	<0.0001
1 year	34	0.822	Very strong	<0.0001