Is it valid to use change scores, i.e. like change in body weight taken between consecutive time points in longitudinal analysis where I'm using nlme/gee?
For example,
bodyweight at hour 3 minus bodyweight at hour 2, body weight at hour 4 minus bodweight at hour 3 to predict a binary outcome? 

Is `logit(odds)=intercept+$\beta_1$*(change in bodyweight between two time points) + $\beta_2$*(change in bodyweight between two other time points) +.... $\beta_n$(change in body weight between $x_{k+1}$ and $x_k$th time) + country effect + time*drug` effect valid?