Using analysis of covariance , early physical therapy showed improvement relative to usual care in disability after 3 months ( mean ODI score : early physical therapy group , 41.3 [ 95 % CI , 38.7 to 44.0 ] at baseline to 6.6 [ 95 % CI , 4.7 to 8.5 ] at 3 months ; usual care group , 40.9 [ 95 % CI , 38.6 to 43.1 ] at baseline to 9.8 [ 95 % CI , 7.9 to 11.7 ] at 3 months ; between-group difference , -3.2 [ 95 % CI , -5.9 to -0.47 ] , P = .02 ) .