Re: Growth Curve Modelling
Hi,
Thank you Joe for noticing the recent publication of a quantitative model relating age and sex to weight across the human life span (Sumpter & Holford 2011).
The WHO growth charts are just that -- charts i.e. a picture with some lines on it. The model that Anita and I have proposed is quantitative and includes both fixed (post-menstrual age, sex) and random effects to describe the increase in weight in a sample of similar size to that used for the WHO charts. Although the model is quite empirical we noticed that sex is associated with weight differences only in the very young (<1 y) and after about 12 y of age. Children in between these ages have similar weight for age irrespective of sex.
We did not find any quantitative models published before but if Nyashadzaishe did find some please let us know. We would be happy to send the NM-TRAN code for our model and its parameters if anyone wants to use it.
The population we used is perhaps more appropriate for simulations of weight in clinical trials because we used subjects who had been participants in clinical trials (mainly PK studies). The WHO population was selected to represent the ideal pattern of growth with what was thought to be optimal nutrition.
If anyone would like to contribute data (age, weight, sex are all that is required for each subject) then we would be happy to extend our analysis. Our data tended to be concentrated in the under 1 year of age group so more observations in older children and adults would be very useful.
Best wishes,
Nick
Sumpter AL, Holford NHG. Predicting weight using postmenstrual age -- neonates to adults. Pediatric Anesthesia. 2011;21(3):309-15.
Quoted reply history
On 18/02/2011 3:09 a.m., Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST) wrote:
> Nyashadzaishe,
>
> UK and I believe WHO growth charts are derived using LMS method which you can do in R - look for papers by TJ Cole. I also suspect you might get a response from a certain NHG Holford telling you to look at his NONMEM method: Paediatr Anaesth. 2011 Mar;21(3):309-15 - I have only skimmed this paper but I think the introduction gives a review of possible methods.
>
> BW,
> Joe
>
> ------------------------------------------------------------------------
>
> *From:* [email protected] [ [email protected] ] On Behalf Of nyashadzaishe mafirakureva [ [email protected] ]
>
> *Sent:* 17 February 2011 13:24
> *To:* [email protected]
> *Subject:* [NMusers] Growth Curve Modelling
>
> I am trying to model growth in children (1-20 years) with a particular disease condition in NONMEM, R or any other software. There seem to be a lack of concensus in literature on the functions (models) one can use. I am therefore looking for some pointers from anyone who could have worked on something similar before.
>
> Thank you
>
> --
> Nyashadzaishe Mafirakureva
>
> ********************************************************************************************************************
>
> This message may contain confidential information. If you are not the intended recipient please inform the
>
> sender that you have received the message in error before deleting it.
>
> Please do not disclose, copy or distribute information in this e-mail or take any action in reliance on its contents:
>
> to do so is strictly prohibited and may be unlawful.
>
> Thank you for your co-operation.
>
> NHSmail is the secure email and directory service available for all NHS staff in England and Scotland NHSmail is approved for exchanging patient data and other sensitive information with NHSmail and GSi recipients NHSmail provides an email address for your career in the NHS and can be accessed anywhere For more information and to find out how you can switch, visit www.connectingforhealth.nhs.uk/nhsmail
>
> ********************************************************************************************************************
--
Nick Holford, Professor Clinical Pharmacology
Dept Pharmacology& Clinical Pharmacology
University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53
email: [email protected]
http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford