Blood Urea Nitrogen Is Associated with In-Hospital Mortality in Critically Ill Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Propensity Score Matching Analysis

Round 1

Reviewer 1 Report

A very interesting study which aims to investigate the relationship be- 19 tween BUN level and in-hospital mortality in patients with AECOPD admitted to the ICU.

The results showed that higher BUN levels were significantly associated with an increased risk of in-hospital mortality in critically ill patients with AECOPD. It was proven that BUN may be useful biomarker in the risk stratification of critically ill AECOPD patients. 

Author Response

Comment: A very interesting study which aims to investigate the relationship be- 19 tween BUN level and in-hospital mortality in patients with AECOPD admitted to the ICU. The results showed that higher BUN levels were significantly associated with an increased risk of in-hospital mortality in critically ill patients with AECOPD. It was proven that BUN may be useful biomarker in the risk stratification of critically ill AECOPD patients. 

Response: I am pleased to resubmit for publication the revised version of manuscript ID: jcm-1966865 entitled “Blood urea nitrogen is associated with in-hospital mortality in critically ill patients with acute exacerbation of chronic obstructive pulmonary disease: A propensity score matching analysis” We appreciate the constructive criticism of the reviewers.  We have addressed each of their concerns as outlined below. We have used the ‘Track changes’ feature of Microsoft Word for the corrections.

Thank you very much, and we wish to express our appreciation for your in-depth comments, suggestions, and corrections, which have greatly improved the manuscript. We invited authors from English-speaking countries to modify the language of the manuscript after we revised the manuscript. We have tried our best to avoid grammatical mistakes in the manuscript. If there are any remaining concerns that we did not address, we would be happy to revise them again.

Reviewer 2 Report

The manuscript entitled: Blood urea nitrogen is associated with in-hospital mortality in critically ill patients with acute exacerbation of chronic obstructive pulmonary disease: A propensity score matching analysis has been reviewed. Overall, this manuscript is written exceptionally well. The English language is very good, and the sections follow clearly.

Minor Queries/Comments:

·       Please remove the italic from the introduction.

·       Please revise the entire manuscript and replace P=0.000 with P<0.001.

·       Statistical analysis. Line 120. Is it P<0.1 or P≤0.1? Please adjust Table 2 accordingly.

·       Please clarify for each p-value reported whether you used a t-test or a Mann-Whitney U test. Could you please explain where the authors have represented the data as Mean ± SD? 

Author Response

Comments and Suggestions for Authors

The manuscript entitled: Blood urea nitrogen is associated with in-hospital mortality in critically ill patients with acute exacerbation of chronic obstructive pulmonary disease: A propensity score matching analysis has been reviewed. Overall, this manuscript is written exceptionally well. The English language is very good, and the sections follow clearly.

Response: I am pleased to resubmit for publication the revised version of manuscript ID: jcm-1966865 entitled “Blood urea nitrogen is associated with in-hospital mortality in critically ill patients with acute exacerbation of chronic obstructive pulmonary disease: A propensity score matching analysis” We appreciate the constructive criticism of the reviewers.  We have addressed each of their concerns as outlined below. We have used the ‘Track changes’ feature of Microsoft Word for the corrections.

Thank you very much, and we wish to express our appreciation for your in-depth comments, suggestions, and corrections, which have greatly improved the manuscript.

Minor Queries/Comments:

Comment 1: Please remove the italic from the introduction.

Response 1: We have removed the italic from the introduction.

Comment 2: Please revise the entire manuscript and replace P=0.000 with P<0.001.

Response 2: We have revised the entire manuscript and replaced P=0.000 with P<0.001.

Comment 3: Statistical analysis. Line 120. Is it P<0.1 or P≤0.1? Please adjust Table 2 accordingly.

Response 3: In line 120, it is P<0.1 and the information in Table 2 is correct.

Comment 4:  Please clarify for each p-value reported whether you used a t-test or a Mann-Whitney U test. Could you please explain where the authors have represented the data as Mean ± SD? 

Response 4: Thank you very much for your comment. We have revised this sentence as “ The Kolmogorov-Smirnov test was used to determine if variables were normally distributed. If the data were normally distributed, we reported it as a mean ± standard deviation (SD) and used the independent sample t-test to compare all variables. When the data were not normally distributed, the variables were expressed as the median with interquartile range (IQR), and the Mann-Whitney test was used.” However, in the present study, the data were not normally distributed (using the Kolmogorov-Smirnov test); therefore, we used the Mann-Whitney test. In the present study, we haven’t represented the data as Mean ± SD. (Note: This section is in Lines 113-115 on Page 3 of the revised manuscript)