Table II.

Mean change score for each measure between the preoperative value and different times postoperatively

PROMs	Mean 3 mths postoperative change score (95% CI); p-value*	Mean 6 mths postoperative change score (95% CI); p-value*	Mean 12 mths postoperative change score (95% CI); p-value*	Change in score between 3 and 6 mths (95% CI); p-value*	Change in score between 6 and 12 mths (95% CI); p-value*
OKS	12.68 (12.01 to 13.36); < 0.001	15.45 (14.79 to 16.12); < 0.001	16.27 (15.56 to 16.98); < 0.001	2.74 (2.32 to 3.16); < 0.001	0.81 (0.41 to 1.20); < 0.001
EQ-5D	0.12 (0.11 to 0.13); < 0.001	0.14 (0.13 to 0.16); < 0.001	0.15 (0.14 to 0.17); < 0.001	0.03 (0.02 to 0.03); < 0.001	0.01 (-0.003 to 0.02); 0.168
EQ-5D VAS	4.40 (2.99 to 5.82); < 0.001	5.28 (3.90 to 6.66); < 0.001	4.84 (3.39 to 6.29); < 0.001	1.03 (-0.08 to 2.14); 0.068	-0.97 (-2.13 to 0.19); 0.102
PROMIS Physical Health	4.97 (4.60 to 5.33); < 0.001	5.60 (5.25 to 5.95); < 0.001	5.57 (5.17 to 5.97); < 0.001	0.73 (0.44 to 1.03); < 0.001	-0.06 (-0.36 to 0.24); 0.677
PROMIS Mental Health	0.03 (-0.34 to 0.40); 0.875	0.18 (44.16 to 44.98); 0.349	0.11 (-0.29 to 0.52); 0.583	0.15 (-0.09 to 0.38); 0.215	-0.10 (-0.33 to 0.14); 0.421

^*Paired-samples Student’s t-tests

PROMs, patient-reported outcome measures; CI, confidence interval; OKS, Oxford Knee Score; EQ-5D, EuroQol five-dimensions; VAS, visual analogue scale; PROMIS, Patient-Reported Outcomes Measurement Information System