Reviewer's report
Title:The association between cecal insertion time and colorectal neoplasm
detection
Version: 1Date:31 March 2013
Reviewer: Christian Stock
Reviewer's report:
The authors aimed to determine the association between cecal insertion time and
colorectal neoplasm detection rate in colonoscopy screening. They conducted a
cross-sectional analysis of 12,679 colonoscopies performed by 23
gastroenterologists in a single center and concluded that shorter insertion times
are associated with increased rates of detection of small adenomas <5 mm.
The topic of the study is timely and of interest to BMC Gastroenterology. Study
population and procedures are well described in the manuscript, which is
generally well written. Important limitations are addressed.
Major Compulsory Revisions
1. My main concern is with the statistical approach. Odds ratios and confidence
intervals for the presence of any adenoma for the 3 highest quartiles of insertion
time vs. the lowest quartile of insertion time were calculated using conditional
logistic regression. It is unclear why insertion time was dichotomized and not
treated as a categorical variable with 1 category for each quartile (an 1 reference
category) or as a continuous variable. Moreover, also other explanatory variables
were dichotomized (withdrawal time and BMI, i.e. dummy variable coding).
Thereby a lot of information is lost and it seems somewhat problematic to
conclude that there is an inverse association between insertion time and
detection of small adenomas based on a comparison of only 2 categories. The
authors might justify and discuss their approach in more detail and/ or present
results from sensitivity analyses treating "insertion time" (and perhaps also
"withdrawal time") differently.
2. The authors state that multiple imputation was used. Information on the portion
of the data that was missing and a complete case analysis should be provided.
Minor Essential Revisions
3. Is reference #1 correct? Its title does not suggest that it is related to the first
sentence.
4. The authors might briefly indicate already in the background section why
insertion time was investigated and why it could potentially be a quality indicator
for colonoscopy. Currently they state only that information is limited.
5. Page 17, 2nd paragraph: replace "body index" by "BMI".
6. The authors might comment on the generalizability of their findings.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests.
Reviewer's report
Title:The association between cecal insertion time and colorectal neoplasm
detection
Version: 1Date:31 March 2013
Reviewer: Christian Stock
Reviewer's report:
The authors aimed to determine the association between cecal insertion time and
colorectal neoplasm detection rate in colonoscopy screening. They conducted a
cross-sectional analysis of 12,679 colonoscopies performed by 23
gastroenterologists in a single center and concluded that shorter insertion times
are associated with increased rates of detection of small adenomas <5 mm.
The topic of the study is timely and of interest to BMC Gastroenterology. Study
population and procedures are well described in the manuscript, which is
generally well written. Important limitations are addressed.
Major Compulsory Revisions
1. My main concern is with the statistical approach. Odds ratios and confidence
intervals for the presence of any adenoma for the 3 highest quartiles of insertion
time vs. the lowest quartile of insertion time were calculated using conditional
logistic regression. It is unclear why insertion time was dichotomized and not
treated as a categorical variable with 1 category for each quartile (an 1 reference
category) or as a continuous variable. Moreover, also other explanatory variables
were dichotomized (withdrawal time and BMI, i.e. dummy variable coding).
Thereby a lot of information is lost and it seems somewhat problematic to
conclude that there is an inverse association between insertion time and
detection of small adenomas based on a comparison of only 2 categories. The
authors might justify and discuss their approach in more detail and/ or present
results from sensitivity analyses treating "insertion time" (and perhaps also
"withdrawal time") differently.
2. The authors state that multiple imputation was used. Information on the portion
of the data that was missing and a complete case analysis should be provided.
Minor Essential Revisions
3. Is reference #1 correct? Its title does not suggest that it is related to the first
sentence.
4. The authors might briefly indicate already in the background section why
insertion time was investigated and why it could potentially be a quality indicator
for colonoscopy. Currently they state only that information is limited.
5. Page 17, 2nd paragraph: replace "body index" by "BMI".
6. The authors might comment on the generalizability of their findings.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests.
Please review this paper.
user
Reviewer's report
Title:The association between cecal insertion time and colorectal neoplasm
detection
Version: 1Date:31 March 2013
Reviewer: Christian Stock
Reviewer's report:
The authors aimed to determine the association between cecal insertion time and
colorectal neoplasm detection rate in colonoscopy screening. They conducted a
cross-sectional analysis of 12,679 colonoscopies performed by 23
gastroenterologists in a single center and concluded that shorter insertion times
are associated with increased rates of detection of small adenomas <5 mm.
The topic of the study is timely and of interest to BMC Gastroenterology. Study
population and procedures are well described in the manuscript, which is
generally well written. Important limitations are addressed.
Major Compulsory Revisions
1. My main concern is with the statistical approach. Odds ratios and confidence
intervals for the presence of any adenoma for the 3 highest quartiles of insertion
time vs. the lowest quartile of insertion time were calculated using conditional
logistic regression. It is unclear why insertion time was dichotomized and not
treated as a categorical variable with 1 category for each quartile (an 1 reference
category) or as a continuous variable. Moreover, also other explanatory variables
were dichotomized (withdrawal time and BMI, i.e. dummy variable coding).
Thereby a lot of information is lost and it seems somewhat problematic to
conclude that there is an inverse association between insertion time and
detection of small adenomas based on a comparison of only 2 categories. The
authors might justify and discuss their approach in more detail and/ or present
results from sensitivity analyses treating "insertion time" (and perhaps also
"withdrawal time") differently.
2. The authors state that multiple imputation was used. Information on the portion
of the data that was missing and a complete case analysis should be provided.
Minor Essential Revisions
3. Is reference #1 correct? Its title does not suggest that it is related to the first
sentence.
4. The authors might briefly indicate already in the background section why
insertion time was investigated and why it could potentially be a quality indicator
for colonoscopy. Currently they state only that information is limited.
5. Page 17, 2nd paragraph: replace "body index" by "BMI".
6. The authors might comment on the generalizability of their findings.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests.
assistant