SKFS scores also showed a significant improvement in the active laser group compared with the placebo laser group at the last treatment session ( median difference -15 , 95 % CI of the difference -27 to -2 ; P = 0.035 ) and 6 months post intervention ( median difference -21 , 95 % CI of the difference -34 to -7 ; P = 0.006 ) using the Mann-Whitney U test .