Compared with the no intervention group ( mean change score , 0.5 ; 95 % CI , -4.8 to 5.8 ; P = .91 ) , both groups undergoing supplemental chamber procedures showed improvement in symptoms on the RPQ ( mean change score , 5.4 ; 95 % CI , -0.5 to 11.3 ; P = .008 in the HBO group and 7.0 ; 95 % CI , 1.0-12 .9 ; P = .02 in the sham group ) .