The mean ( SD ) change in pain intensity ( LOCF ) from start of double-blind treatment to week 12 was as follows : placebo , 1.30 ( 2.43 ) ; tapentadol ER , 0.28 ( 2.04 ; least squares mean difference , -0.95 [ 95 % CI -1.42 to -0.49 ] ; P < 0.001 ) .