Table 6. Change in pain scores (∆VAS) from pre-op to last follow-up by surgical center.

Center	n	Average	SD	Max	Min	P value†
1	148	46.8	33.3	100	−30	<0.01
2	43	39.8	33.1	100	−50	0.60
3	44	36.1	33.8	100	−60	0.90
4	107	22.1	35.2	100	−50	<0.01
Total/average	342	36.8	35.4	100	−60	1.00

^†, P value for each center in comparison to average for all centers.