Review for 10.1186/1471-230X-6-5 (2006)

Reviewer's report 
 Lifestyle as a predictor for colonic neoplasia in asymptomatic individuals Title: 
 3  7 September 2005 Version: Date: 
 A Chao Reviewer: 
Reviewer's report: 
This paper reports on a study of men and women aged 51-55 years who participated in the 
screening arm of a randomized control screening trial. The report examined whether a short 
questionnaire can capture adequate information to assess lifestyle factors in relation to colorectal 
neoplasia, and identified lifestyle factors associated with the prevalence of colorectal neoplasia. The 
study is based on a large population-based sample and is appropriately analyzed; however, the 
description of the study design and methods needs clarification. The following considerations may 
help to strengthen the report: 
1. The authors refer to this study as a “nested case-control” study. Based on the description of the 
study methods and Figure 1, this study should be more appropriately considered a cross-sectional 
study where participants first completed a questionnaire and were then screened by flexible sigmoidoscopy (FS); the outcome (case or controls status) was determined after screening and 
participants were unaware of the presence of neoplasia. Please explain how this is a nested 
case-control study; if it is not then please change the terminology used. 
2. Please provide more information about the design of the randomized screening trial in this report. 
What were the other arms that participants could be randomized to? What was the response rate of 
all invitees? What was the duration of the trial? How often were participants examined (text states 
once-only FS)? What was the loss to follow-up rate among participants in different arms? The fact 
that these basic details have been described elsewhere is not helpful to readers of this report. 
3. The text states that half of the 6,961 screenees were randomized to a combination of FS and 
FOBT but this randomization is not indicated on Figure 1. What other screening algorithms were 
participants randomized to? How was it determined that participants were asymptomatic? The description of both the original trial and the current study needs to be clarified and Figure 1 revised. 
4. Because the association between colorectal neoplasia and several lifestyle factors differ by 
gender in the literature, and apparently in this study in relation to BMI, it would be good to present the data separately by gender. 
5. The comparison among heavy smokers only (page 12) should be omitted since this is such a 
small group of people. 
6. What was the rationale for excluding family history of colorectal neoplasia and personal history of 
polyps (or previous endoscopy) from the questionnaire? 
7. Please rephrase this sentence on page 13 – “This suggests that not all risk factors may be limited 
to characterization of the most reluctant compliers.” 
8. Please explain the last full sentence on page 13. Do you mean to say that 70% of all neoplasia 
could be detected in the distal colon and rectum based on another study? What do you mean by 
“this threshold”? I wonder if potentially misclassifying the outcome of as many as 7% of participants 
can really be considered “low” without impact on the results. It would be good for the authors to 
discuss how this potential misclassification could have impacted results (or not) and whether the risk 
factors examined are more or less likely to be associated with tumors in the proximal colon. 
9. Pages 14-15, the authors report a lack of association between diet and advanced neoplasia, and 
that the association between diet and prevalence of adenoma is inconclusive. They conclude that 
these are not explained by the design of their questionnaire and that the questionnaire was 
adequate in picking up the most consistent associations. It would be good for the authors to show data in support of these conclusions. 
10. Table 1: please show the proportion in various smoking habit categories instead of the coding 
mean. 
11. Table 1: please explain the mean (SD) for the dietary habits, is this an average of coding or an 
average of units of foods consumed per day? 
Level of interest 
----------------- 
- An article whose findings are important to those with closely related research interests. 
The risk factors examined in this report have been studied in much more detail in other large studies, 
both cohort and case-control studies. The current study adds information from a population-based 
study population in Norway and finds smoking and BMI associated with increased prevalence of 
neoplasia. The null results on diet could have been due to the crude questionnaire used. 
 Unable to decide on acceptance or rejection until the authors have responded to the What next?: 
major compulsory revisions 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Acceptable Quality of written English: 
 No Statistical review: 
Declaration of competing interests: 
I declare that I have no competing interests.