Review for 10.1186/1471-230X-10-51 (2010)

Reviewer's report
Title:Central Obesity and Atherogenic Dyslipidemia in Metabolic Syndrome are
Associated with Increased Risk for Colorectal Adenoma in a Chinese Population
Version: 2Date:26 February 2010
Reviewer: Jonas Manjer
Reviewer's report:
This study examines the potential association between the MetS (and its single
components) and CR polyps / adenomas.
The study is well designed. The data is suitable for the analysis.
The risk of adenomas has not been thoroughly investigated and is important
considering the relation to colorectal cancer.
The material and methods section need some additions and the data may
actually reveal more information if some additional analyses are performed.
Major Compulsory Revisions have been marked below with” *”. All other
comments are
Discretionary Revisions
Overall, the findings related to CRP are interesting and it can be considered to
introduce this already in the introduction. The novelty of the paper would
increase.
ABSTRACT
Clearly written, easy to follow. Main findings presented.
1. CI:s should always be given.
INTRODUCTION
2. Triglycerides may be mentioned on line 2-3.
*3. A reference should be given concerning cancer statistics in Taiwan.
METHODS
*4. Sampling frame – who was invited to the examination? Rationale for
colonoscopy?
*5. Was this a population-based sample? Public hospital?
*6. Inclusion criteria? Age? Sex?
*7. Invited patients – how many?
*8. Exclusion criteria besides colorectal disease? That is, exclusion before
examination.
*9. Method for CRP should be given.
*10. Weight – without clothes? Light clothing?
11. Consider using SI unit for WC.
*12. Additional questions on HRT and menopausal status seems to have been
part of the examination. Describe how this was assessed and classified!
* 13. Polyps and adenomas were probably classified following a pathological
examination. This should be described more clearly. Which Pathology Dept.?
STATISTICAL ANALYSIS
The analysis is adequate, but there are more aspects that can be covered. The
paper would be more complete following this.
* 14. The Scheffes test should be presented in this section. Rationale? p-value?
* 15. This sentence is not clear: “multinomal log reg analysis was used to
estimate the ORs of Mets by age, MetS status, smoking and alc consumtion
status”. Does it mean that these factors were used as co-variates or that the
potential assoc MetS-adenomas was investigated in different strata of these
factors?
RESULTS
16. Throughout for all tables the definitions of high / low values are also given in
the text and this can be omitted from the tables in order to increase readability.
*17. The use of data on alcohol consumption in these analyses is not clear. Is it
used as a co-variate? In that case it should be presented in table 2.
*18. It is not clear if smoking is adjusted for, see §15 and §17 above.
19. I would strongly suggest that all analyses (table 3) are first performed in all
subjects, and then separately for men and women (also for individual
components of the MetS). Several previous studies have shown that single
factors of the MetS may have opposite association with cancer in men and
women. Such a stratified analysis would be a strength in the current analysis.
*20. Table 3 should include:
- number of cases in each category
- number of healthy subjects in each category
- crude OR:s
- adjusted OR:s
*21. Findings on CRP may be presented in table 3.
22. The definition of the MetS is somewhat arbitrary and differs between different
investigators. The authors may consider also to present OR:s for metabolic
factors analysed as continuous variables.
23. Co-variation is indeed a problem. Would it be possible to include all individual
components in the same multivariate model? Either as dichotomous or
continuous variables.
24. It is not necessary to write “95% CI” in the text following the first definition.
DISCUSSION
The discussion includes a thorough discussion of the findings in relation to
current literature.
There is very little on methodological issues/problems.
*25. Potential misclassification of polyps / adenomas. Several pathologists?
Discuss!
*26. Potential misclassification of metabolic factors? CV:s? Discuss if this is a
potential problem!
*27. Selection bias? – were these patients representative of the entire
background population? If not – would this have affected the conclusion in this
study?
*28. Detection bias? – these patients were asymptomatic – does it affect the
comparison with symptomatic adenomas, clinically significant adenomas? Is this
important from a biological point of view? Discuss!
*29. Additional confounding? Some more additional risk factors for adenomas
that were not assessed? What other factors may be important? Discuss e.g.
lifestyle.
*30. Type I error. A lot of multiple comparisons (many factors) are made. Discuss
the problem of mass-significance. Are the results likely to have been caused by
this? (I don’t believe so!)
Level of interest: An article of outstanding merit and interest in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests /JM