I strongly advise using LSMEANS or SLICE instead of the ESTIMATE statement which requires determining the correct coefficients on the model parameters to estimate the quantity of interest and is a very error prone task. In a binomial or multinomial model, differences like you want are differences of log odds and exponentiating those differences yields odds ratios. You can easily do this with the LSMEANS statement with the DIFF and ODDSRATIO options. You might also want to add the E option to see a table showing the coefficients on the model parameters used to estimate each log odds. Note that in a multinomial model with k response levels, there are k-1 cumulative logits so you will get k-1 log odds estimates for each level of the predictor in the LSMEANS statement. The difference, however, is the same for each logit, so there is only one difference (and odds ratio).   lsmeans Infusion_volume / e diff oddsratio; ... View more