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Open Access Study protocol

Trial Protocol: Using genotype to tailor prescribing of nicotine replacement therapy: a randomised controlled trial assessing impact of communication upon adherence

Theresa M Marteau1*, Marcus R Munafò2, Paul Aveyard3, Chloe Hill1, Sophia Whitwell1, Thomas A Willis1, Rachel A Crockett1, Gareth J Hollands1, Elaine C Johnstone4, Alison J Wright5, A Toby Prevost5, David Armstrong5, Stephen Sutton6 and Ann Louise Kinmonth6

Author Affiliations

1 King's College London, Psychology Department (at Guy's), Health Psychology Section, 5th Floor Bermondsey Wing, Guy's Campus, London SE1 9RT, UK

2 Department of Experimental Psychology, 12a Priory Road, University of Bristol, Bristol, BS8 1TU, UK

3 Primary Care Clinical Sciences, University of Birmingham, Birmingham, B15 2TT, UK

4 University of Oxford, Department of Clinical Pharmacology, Old Road Campus Research Building, Old Road Campus, Headington, Oxford OX3 7DQ, UK

5 King's College London, Department of Primary Care and Public Health Sciences, 5th Floor Capital House, 42 Weston Street, London SE1 3QD, UK

6 University of Cambridge Department of Public Health and Primary Care, Forvie Site, Robinson Way, Cambridge, CB2 0SR, UK

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BMC Public Health 2010, 10:680  doi:10.1186/1471-2458-10-680

Published: 9 November 2010

Abstract

Background

The behavioural impact of pharmacogenomics is untested; informing smokers of genetic test results for responsiveness to smoking cessation medication may increase adherence to this medication. The objective of this trial is to estimate the impact upon adherence to nicotine replacement therapy (NRT) of informing smokers that their oral dose of NRT has been tailored to a DNA analysis. Hypotheses to be tested are as follows:

I Adherence to NRT is greater among smokers informed that their oral dose of NRT is tailored to an analysis of DNA (genotype), compared to one tailored to nicotine dependence questionnaire score (phenotype).

II Amongst smokers who fail to quit at six months, motivation to make another quit attempt is lower when informed that their oral dose of NRT was tailored to genotype rather than phenotype.

Methods/Design

An open label, parallel groups randomised trial in which 630 adult smokers (smoking 10 or more cigarettes daily) using National Health Service (NHS) stop smoking services in primary care are randomly allocated to one of two groups:

i. NRT oral dose tailored by DNA analysis (OPRM1 gene) (genotype), or

ii. NRT oral dose tailored by nicotine dependence questionnaire score (phenotype)

The primary outcome is proportion of prescribed NRT consumed in the first 28 days following an initial quit attempt, with the secondary outcome being motivation to make another quit attempt, amongst smokers not abstinent at six months. Other outcomes include adherence to NRT in the first seven days and biochemically validated smoking abstinence at six months. The primary outcome will be collected on 630 smokers allowing sufficient power to detect a 7.5% difference in mean proportion of NRT consumed using a two-tailed test at the 5% level of significance between groups. The proportion of all NRT consumed in the first four weeks of quitting will be compared between arms using an independent samples t-test and by estimating the 95% confidence interval for observed between-arm difference in mean NRT consumption (Hypothesis I). Motivation to make another quit attempt will be compared between arms in those failing to quit by six months (Hypothesis II).

Discussion

This is the first clinical trial evaluating the behavioural impact on adherence of prescribing medication using genetic rather than phenotypic information. Specific issues regarding the choice of design for trials of interventions of this kind are discussed.

Trial details

Funder: Medical Research Council (MRC)

Grant number: G0500274

ISRCTN: 14352545

Date trial stated: June 2007

Expected end date: December 2009

Expected reporting date: December 2010