Re: Covariate Models Using Weight

Date: Thu, 18 Nov 1999 09:28:55 +0000 From: James <J.G.Wright@ncl.ac.uk> Subject: Re: Covariate Models Using Weight >Dear Nick & Vladimir, > >I too agree that using prior information is essential in building a sensible model but I draw the line at extrapolating from points on a log-log plot representing different species to a clinical population of patients. Do we really believe that a human beings clearance changes in a predictable manner if they put on a few kilos? At least half of the western world is overweight these days. Comparisons using children and adults are necessarily confounded by many factors. I think in this day and age we should be looking for useful predictive covariates rather than claiming we can apply WT^3/4 to all possible drugs and patient populations on very limited evidence. In my personal experience, WT^3/4 and WT may not actually differ very much once other covariates have been used but I would need far more evidence before I could support Nicks view that WT^3/4 is the default choice. > >James