While this difference was not significant ( odds ratio = 1.6 , 95 % CI 0.5-5 .2 , Wald 2 [ df ] = 0.5 [ 1 ] , p = 0.5 ) , naltrexone treatment led to a significantly greater decrease in QUIP-RS ICD score over time compared with placebo ( regression coefficient for interaction term in linear mixed-effects model = -7.37 , F [ df ] = 4.3 [ 1 , 49 ] , p = 0.04 ) .