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		APPENDIX 3 Workshop Summary A workshop was conducted at the forum for the purpose of giving delegates some direct experience of the processes by which the RMA works in deciding on which factors should be included in a Statement of Principles. The workshop was divided into two parts. For the first part, participants were divided into work groups of around eight people and provided with two studies each on which to go through a critical appraisal checklist (see box). Each group was allocated one of two topics relating to issues recently considered by the RMA: hepatitis C as a risk factor for diabetes, and inadequate intake of dietary fibre as a risk factor for colorectal cancer. For the second part of the workshop, participants came back together for a discussion about whether the body of evidence was strong enough to support the inclusion of these risk factors in either the RH or BoP instruments. Participants were provided with a table summarising all the available peer-reviewed studies concerning those particular factors. CRITICAL APPRAISAL CHECKLIST What is the study about? What is the study hypothesis (research question)? What is the study type? What is the outcome factor (disease of interest) and how is it measured? What are the risk factors and how are they measured? Where did the study subjects come from? What are the main results? What is the size of the effect? Are the results statistically significant? What are the confidence intervals? Can the results be explained by anything else apart from the risk factor under consideration? What are the important potential confounders in this association and were they taken into account? Is there any bias in the selection of study subjects or in the measurement of exposures or outcomes? Could the results be explained by chance? What is the evidence for causation? What is the strength of the relationship? Is there a dose response effect? Is it clear that the exposure precedes the outcome? Are the results consistent with other evidence? Do the results make sense from our understanding of biology? Conclusions What conclusions do the authors reach? Do you think that they are reasonable? Professor Andrew Wilson led the discussion on hepatitis C and diabetes after Dr Ian Smith (RMA Secretariat) had gone through the answers to the critical appraisal questions for the two hepatitis C studies. All the groups felt that the material was sufficient only to include the factor in the RH instrument. This was in accordance with the decision of the RMA. Professor Wilson pointed out that in this case the exposure was easy to define, as it was simply a positive blood test. The issue of latency (time interval between exposure and outcome) was harder to resolve because of the lack of available data, particularly a lack certainty about a clear biological mechanism. Different mechanisms would involve different time frames. The most generous interpretation of the data in this case was to have no latency period. The final SOP factor (RH only) was: "having hepatitis C virus infection before the clinical onset/clinical worsening of diabetes mellitus" Professor John Kaldor led the discussion on dietary fibre and colorectal cancer after Andrew Leiboff (RMA Secretariat) had gone through the answers to the critical appraisal questions for the two dietary fibre studies. Professor Kaldor discussed two graphs showing a summary of the results and confidence intervals of all available case-control and cohort studies. Cohort studies are considered to be a stronger form of evidence. He pointed out that in the graph summarising the case-control studies most of the results were below the level of no effect, giving the overall impression that most studies suggest that dietary fibre protects against colorectal cancer. However, the graph summarising cohort studies showed that most of the results indicated no effect, apart from one recent large study. In conclusion, there was enough indication to put a factor in the RH instrument, but insufficient indication to put a factor in the BoP instrument. Professor Kaldor explained that the RMA then had to decide upon the dose of fibre and the length of time in which fibre intake has to be reduced before cancer risk starts to increase. These decisions were based on the information in the available studies. The final SOP factor (RH only) was: "an inability to consume an average daily intake of 20 grams of fibre in food (or a total of 36 500 grams of fibre in food) over a continuous period of five years within the ten years immediately before the clinical onset of malignant neoplasm of the colorectum" Professor Kaldor concluded that these two examples were good illustrations of some of the challenges faced by the RMA when making decisions about risk factors. In relation to hepatitis C and diabetes, the situation was one of having to come up with a decision based on very limited information of varying quality. In relation to dietary fibre and colorectal cancer, there was a lot more evidence available but the results were conflicting and there was an additional need to decide on dose. In either case, the decisions could change if new information from well conducted studies becomes available. Previous | Contents | Next This page last updated 22 March 2005.

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