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"grace pang" <[log in to unmask]>
Hello.
I would like some advice on sample size estimation regarding a genetic
association study I am planning
The aim is to determine if certain haplotypes in the mu opioid receptor
gene are associated with the risk of developing post operative nausea and
vomiting when given fentanyl ( drug that acts on mu opioid receptors)
intraoperatively in surgical patients
Info about the prospective cohort study. I intend to study surgical
patients of the same race undergoing minor day surgery where patients ar
similar in demographics, medical history, preoperative emetic risk,
proceedure and introperative anaaesthetic regime which includes the same
dose of opioid / body weight. Post operatively we'll document which
patients develop nausea, vomiting and / or retching of whether it is mild,
moderate or severe.
Info about post operative nausea and vomiting. With the techinque that will
be used, the incidence of post operative vomiting is about 10-20% ( figure
obtained from previous studies in surgical patients).
Info about the gene. I looked at SNPs of this gene in the 4 HAPMAP
populations and identified SNPs that were common to all populations and
allele frequency >4% as the incidence of opioid induced emesis is
relatively similar accross the races. Out of all the haplotypes that were
generated using the EM algorithm, only 3 haplotypes had a haplotype
frequency of >4% in all 4 populations. Each haplotype consisted of 13
SNPs. The SNPs were 2 promoter SNPs and the rest were intronic SNPs These
SNPs are not linked
There is currently no info avail in the lit search on inheritance of post
operative nausea and vomiting (emesis) though there are predisposing
factors which we have taken care to minimise in this study.
I do not know whether these are the causative SNPs for opioid induced
emesis though 2 of the SNPs being promoter SNPs may afect gene expression (
which I'll do seperate lab experiments for).
I would be grateful for some advice on not only sample size estimation as
well as what the role of pilot genetic association studies is i.e is sample
size jut governed by practical and economic reasons or are there more reasons.
thank you
Have a nice day :)
Grace
REPLY TO:
"grace pang" <[log in to unmask]>
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