In the Asn40 group , the observed effect of naltrexone was similar to that in previous trials ( odds ratio , 0.69 ; 95 % CI , 0.41-1 .18 ; P = .17 ) , with a very small naltrexone effect in the Asp40 group ( odds ratio , 1.10 ; 95 % CI , 0.52-2 .31 ; P = .80 ) , contrary to the pattern expected a priori .