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.

Why does genetic causal information alter perceived treatment effectiveness? An analogue study.

Objectives: When a health problem is perceived as having a genetic cause, this appears to increase the perceived effectiveness of pharmacological treatments and reduce perceived effectiveness of non-pharmacological treatments. Potential mediators of this effect include causal attributions, perceived severity, and perceived control over the health problem. This study aimed to use experimental methods to establish which beliefs mediate the effect of genetic causal information on perceived effectiveness of treatments.

Trial Protocol: Communicating DNA-based risk assessments for Crohn's disease: a randomised controlled trial assessing impact upon stopping smoking.

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 impact of numeracy on reactions to different graphic risk presentation formats: An experimental analogue study.

Objectives: Numeracy, the ability to process basic mathematical concepts, may affect responses to graphical displays of health risk information. Displays of probabilistic risk information using grouped dots are easier to understand than displays using dispersed dots. However, dispersed dots may better convey the randomness with which health threats occur, so increasing perceived susceptibility.