Re: Centering (was Re: Missing covariates)

Date: Thu, 05 Jul 2001 14:07:11 +1200 From: Nick Holford <n.holford@auckland.ac.nz> Subject: Re: Centering (was Re: Missing covariates) Diane Mould wrote: > Nick Holford's earlier comments to NMUSERS about routinely using a value of 70 to > center creatinine clearance is just such an example of picking a user-friendly value. In fact I suggested standard values of 70 kg, 40 years and 6 L/h creatinine clearance. While 70 mL/min (4.2 L/h) might be a common median in a patient population the idea of centering on 6 L/h (100 mL/min) is because this would be considered "normal" for a healthy 70 kg, 40 year old. The other standard covariate to consider is sex. I agree with Diane that sex should be user-friendly but picking its value depends on the gender covariate which is hard to quantitate. Kim JS, Nafziger AN. Is it sex or is it gender? Clin Pharmacol Ther 2000;68(1):1-3 -- Nick Holford, Divn Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.htm