Change from baseline for the BMI z score in the inpatient group was -18.0 % ( P = .001 ) immediately after treatment , -8.5 % ( P = .008 ) at 18 months , and -6.3 % ( P = .38 ) at 30 months ; in the ambulatory group , changes from baseline were -10.5 % ( P = .001 ) , -6.2 % ( P = .39 ) , and -1.5 % ( P > .99 ) , respectively .