For the sham group ( n = 40 ) , estimated change in the Oswestry disability index from the adjusted baseline value was -4.7 ( 95 % confidence intervals -0.6 to -8.8 ) at 6 weeks , -11.4 ( -6.3 to -14.5 ) at 12 weeks , and -14.3 ( -10.0 to -18.7 ) at 52 weeks .
