Title: The 30-day hospital readmission and mortality after surgery in colorectal cancer patients
Version: 3 Date: 13 May 2022
Reviewer's report:
This manuscript addresses the major concern of readmissions after colorectal surgery. The
authors utilized data from the Ministry of National Guard-Health Affairs Cancer Registry to
determine significant predictors of readmission, reasons for readmission, and assessed survival
rates.
Major Comments
1) The t-test is not appropriate for heavily skewed data. Was the appropriateness of the t-test
assessed? LOS and operation time are likely skewed.
2) A very large number of otherwise eligible patients were missing a discharge date for their
index admission and were thus excluded. Do you have an explanation for why so many patients
were missing discharge dates? I’m concerned these patients may be systematically different
from those whose discharge date was present, potentially skewing the results. Were there any
other variables included with similarly large percent missingness?
3) First paragraph of the results section: “Compared to non-readmitted patients, readmitted
patients were less likely to have regional stage (55.10% vs. 63.52%; P-value=0.03) but more
likely to have a distant metastasis (34.69 vs. 17.26; P-value=0.03).” This is not the correct
interpretation of the p-value of 0.03 from the chi-square test. Please correct. The p-value quoted
simply states that there is a significant association between readmission and stage, the p-value
does not directly compare the proportions in the two situations listed.
4) What was the justification for splitting table 3 based on tumor location? It would be interesting
to see this same analysis done with surgery approach and type.
5) 49 patients were readmitted, thus your multivariable model should have no more than 5 terms
included. The model presented has 12 thus is overfit and cannot be generalized to the overall
population. A forward stepwise approach would be more appropriate capping the terms at 5.
Further, treating Age, BMI, and LOS as continuous variables would be best to avoid loss of
power.
6) What statistical methods were used for the survival analysis? These should be addressed in
the statistical methods section.
Minor Comments
1) Last sentence of second paragraph of the introduction as the period in the wrong place.
2) “Multivariable” is the correct term to use throughout as opposed to “Multivariate”.
3) In Table 1 the total column should have a “% or SD” as opposed to only “%”.
4) Please be consistent in reporting percentages, use either 1 or 2 decimal places throughout; the
% symbol is also sporadically missing.
Title: The 30-day hospital readmission and mortality after surgery in colorectal cancer patients
Version: 3 Date: 13 May 2022
Reviewer's report:
This manuscript addresses the major concern of readmissions after colorectal surgery. The
authors utilized data from the Ministry of National Guard-Health Affairs Cancer Registry to
determine significant predictors of readmission, reasons for readmission, and assessed survival
rates.
Major Comments
1) The t-test is not appropriate for heavily skewed data. Was the appropriateness of the t-test
assessed? LOS and operation time are likely skewed.
2) A very large number of otherwise eligible patients were missing a discharge date for their
index admission and were thus excluded. Do you have an explanation for why so many patients
were missing discharge dates? I’m concerned these patients may be systematically different
from those whose discharge date was present, potentially skewing the results. Were there any
other variables included with similarly large percent missingness?
3) First paragraph of the results section: “Compared to non-readmitted patients, readmitted
patients were less likely to have regional stage (55.10% vs. 63.52%; P-value=0.03) but more
likely to have a distant metastasis (34.69 vs. 17.26; P-value=0.03).” This is not the correct
interpretation of the p-value of 0.03 from the chi-square test. Please correct. The p-value quoted
simply states that there is a significant association between readmission and stage, the p-value
does not directly compare the proportions in the two situations listed.
4) What was the justification for splitting table 3 based on tumor location? It would be interesting
to see this same analysis done with surgery approach and type.
5) 49 patients were readmitted, thus your multivariable model should have no more than 5 terms
included. The model presented has 12 thus is overfit and cannot be generalized to the overall
population. A forward stepwise approach would be more appropriate capping the terms at 5.
Further, treating Age, BMI, and LOS as continuous variables would be best to avoid loss of
power.
6) What statistical methods were used for the survival analysis? These should be addressed in
the statistical methods section.
Minor Comments
1) Last sentence of second paragraph of the introduction as the period in the wrong place.
2) “Multivariable” is the correct term to use throughout as opposed to “Multivariate”.
3) In Table 1 the total column should have a “% or SD” as opposed to only “%”.
4) Please be consistent in reporting percentages, use either 1 or 2 decimal places throughout; the
% symbol is also sporadically missing.
Please review this paper.
user
Title: The 30-day hospital readmission and mortality after surgery in colorectal cancer patients
Version: 3 Date: 13 May 2022
Reviewer's report:
This manuscript addresses the major concern of readmissions after colorectal surgery. The
authors utilized data from the Ministry of National Guard-Health Affairs Cancer Registry to
determine significant predictors of readmission, reasons for readmission, and assessed survival
rates.
Major Comments
1) The t-test is not appropriate for heavily skewed data. Was the appropriateness of the t-test
assessed? LOS and operation time are likely skewed.
2) A very large number of otherwise eligible patients were missing a discharge date for their
index admission and were thus excluded. Do you have an explanation for why so many patients
were missing discharge dates? I’m concerned these patients may be systematically different
from those whose discharge date was present, potentially skewing the results. Were there any
other variables included with similarly large percent missingness?
3) First paragraph of the results section: “Compared to non-readmitted patients, readmitted
patients were less likely to have regional stage (55.10% vs. 63.52%; P-value=0.03) but more
likely to have a distant metastasis (34.69 vs. 17.26; P-value=0.03).” This is not the correct
interpretation of the p-value of 0.03 from the chi-square test. Please correct. The p-value quoted
simply states that there is a significant association between readmission and stage, the p-value
does not directly compare the proportions in the two situations listed.
4) What was the justification for splitting table 3 based on tumor location? It would be interesting
to see this same analysis done with surgery approach and type.
5) 49 patients were readmitted, thus your multivariable model should have no more than 5 terms
included. The model presented has 12 thus is overfit and cannot be generalized to the overall
population. A forward stepwise approach would be more appropriate capping the terms at 5.
Further, treating Age, BMI, and LOS as continuous variables would be best to avoid loss of
power.
6) What statistical methods were used for the survival analysis? These should be addressed in
the statistical methods section.
Minor Comments
1) Last sentence of second paragraph of the introduction as the period in the wrong place.
2) “Multivariable” is the correct term to use throughout as opposed to “Multivariate”.
3) In Table 1 the total column should have a “% or SD” as opposed to only “%”.
4) Please be consistent in reporting percentages, use either 1 or 2 decimal places throughout; the
% symbol is also sporadically missing.
assistant