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1.  Trial Protocol: Communicating DNA-based risk assessments for Crohn's disease: a randomised controlled trial assessing impact upon stopping smoking 
BMC Public Health  2011;11:44.
Background
Estimates of the risk of developing Crohn's disease (CD) can be made using DNA testing for mutations in the NOD2 (CARD15) gene, family history, and smoking status. Smoking doubles the risk of CD, a risk that is reduced by stopping. CD therefore serves as a timely and novel paradigm within which to assess the utility of predictive genetic testing to motivate behaviour change to reduce the risk of disease. The aim of the study is to describe the impact upon stopping smoking of communicating a risk of developing CD that incorporates DNA analysis. We will test the following main hypothesis:
Smokers who are first degree relatives (FDRs) of CD probands are more likely to make smoking cessation attempts following communication of risk estimates of developing CD that incorporate DNA analysis, compared with an equivalent communication that does not incorporate DNA analysis.
Methods/design
A parallel groups randomised controlled trial in which smokers who are FDRs of probands with CD are randomly allocated in families to undergo one of two types of assessment of risk for developing CD based on either:
i. DNA analysis, family history of CD and smoking status, or
ii. Family history of CD and smoking status
The primary outcome is stopping smoking for 24 hours or longer in the six months following provision of risk information. The secondary outcomes are seven-day smoking abstinence at one week and six month follow-ups. Randomisation of 470 smoking FDRs of CD probands, with 400 followed up (85%), provides 80% power to detect a difference in the primary outcome of 14% between randomised arms, at the 5% significance level.
Discussion
This trial provides one of the strongest tests to date of the impact of communicating DNA-based risk assessment on risk-reducing behaviour change. Specific issues regarding the choice of trial design are discussed.
Trial Registration
ISRCTN: ISRCTN21633644
doi:10.1186/1471-2458-11-44
PMCID: PMC3036624  PMID: 21247480
2.  Effect of communicating DNA based risk assessments for Crohn’s disease on smoking cessation: randomised controlled trial 
Objective To test the hypothesis that communicating risk of developing Crohn’s disease based on genotype and that stopping smoking can reduce this risk, motivates behaviour change among smokers at familial risk.
Design Parallel group, cluster randomised controlled trial.
Setting Families with Crohn’s disease in the United Kingdom.
Participants 497 smokers (mean age 42.6 (SD 14.4) years) who were first degree relatives of probands with Crohn’s disease, with outcomes assessed on 209/251 (based on DNA analysis) and 217/246 (standard risk assessment).
Intervention Communication of risk assessment for Crohn’s disease by postal booklet based on family history of the disease and smoking status alone, or with additional DNA analysis for the NOD2 genotype. Participants were then telephoned by a National Health Service Stop Smoking counsellor to review the booklet and deliver brief standard smoking cessation intervention. Calls were tape recorded and a random subsample selected to assess fidelity to the clinical protocol.
Main outcome measure The primary outcome was smoking cessation for 24 hours or longer, assessed at six months.
Results The proportion of participants stopping smoking for 24 hours or longer did not differ between arms: 35% (73/209) in the DNA arm versus 36% (78/217) in the non-DNA arm (difference −1%, 95% confidence interval −10% to 8%, P=0.83). The proportion making a quit attempt within the DNA arm did not differ between those who were told they had mutations putting them at increased risk (36%), those told they had none (35%), and those in the non-DNA arm (36%).
Conclusion Among relatives of patients with Crohn’s disease, feedback of DNA based risk assessments does not motivate behaviour change to reduce risk any more or less than standard risk assessment. These findings accord with those across a range of populations and behaviours. They do not support the promulgation of commercial DNA based tests nor the search for gene variants that confer increased risk of common complex diseases on the basis that they effectively motivate health related behaviour change.
Trial registration Current Controlled Trials ISRCTN21633644.
doi:10.1136/bmj.e4708
PMCID: PMC3401124  PMID: 22822007

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