The mean ( SE ) changes in the KOOS Pain subscale score at week 14 were 13.6 ( 1.8 ) and 14.8 ( 1.8 ) points in the corticosteroid and placebo groups , respectively , corresponding to a statistically insignificant mean difference of 1.2 points ( 95 % CI , -3.8 to 6.2 ; P = .64 ) .