Review for 10.1186/s12876-019-1128-4 (2019)

Reviewer ’s report  
 
Title: Evaluation of Clinical Risk Factors for Developing Ple ural Empyema Secondary to Liver  
Abscess  
 
Version: 0 Date: 26 Aug 2019  
 
Reviewer: Nadia Ovchinsky  
 
Reviewer's report:  
 
This is a study investigating clinical manifestations and risk factors of developing of pleural 
effusions a nd pleural empyema in patients with pyogenic hepatic abscess (PLA).  
 
This study evaluates 234 patients presenting with PLA. 4.3% of all patients and 8.8% of patients 
with pleural effusions developed pleural empyema. This clinical data is important as it de fines 
important risk factors for development of complicated pleural effusions and empyema requiring 
interventions such as thoracenthesis, chest tube insertion, and surgical debridement.  
 
In the introduction the authors mention few reports evaluating the r isk of pleural empyema in 
association with PLA, however references are not provided and discussion of prior reports is not 
included.  
 
The presence of biliary disease was identified as one of the main risk factors for development of 
pleural empyema. Biliar y disease is defined as cholecystitis/cholangitis, choledocholithiasis, and 
"history of cholecystectomy of any cause in the past or at the time of PLA diagnosis". History of 
cholecystectomy in the past should not be considered the same risk factor as activ e biliary 
inflammatory or infectious condition at the time of PLA. It may be more accurate to focus on 
patients with active biliary disease and exclude those with history of uncomplicated 
cholecystectomy in the past without ongoing cholangitis.  
 
Liver dise ase is not defined for this patient population.  Presence of liver disease may change 
risk factors for developing pleural effusions (this may be secondary to complications of portal 
hypertension and may not be necessarily related to PLA).  In patient chara cteristics, it states that 
3 patients had liver cirrhosis and 3 patients had HBV. Are these the same patients? Were there 
other patients with liver disease such as HCV? Were there any patients with hepatocellular 
carcinoma? It does state that patients with  PLA post -TACE were excluded.  
 
It may be helpful to provide normal values for certain laboratory parameters in the tables as a 
reference for readers (especially inflammatory markers such as CRP which are not standardized).  
 
Under Table 1 (page 16, line 39 ), the Number of abscess should be corrected from ≤3 to ≥3.  
 
In figure 1, it states "He was suffered from chronic cholangitis". Please change to "he was 
suffering".  
 
Authors conclude that location of liver abscess near the right diaphragm, detection of mi xed 
microorganisms in PLA, and biliary disease could affect the development of pleural empyema. 
However, it would be more accurate to state that these are risk factors of developing more 
complex pleural effusions requiring interventions such as thoracenthe sis, chest tube insertion, 
and surgical debridement. In the multivariate analysis for risk factors of pleural empyema, only 
biliary disease and bilateral pleural effusions were identified as risk factors.  
 
The main limitation of this study is its retrospec tive analysis looking at patient data in a single 
center over a decade, which limits full data collection of detailed laboratory values, antibiotic 
regimen, and other detailed clinical parameters. However, PLA complicated by complicated 
pleural effusions/e mpyema is a rare occurrence. Therefore, a description of clinical manifestation 
and risk factors in this large sample of patients with PLA is important.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your c omments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considerin g the following questions:  
 
1.  Have you in the past five years received reimbursements, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
2.  Do yo u hold any stocks or shares in an organisation t hat may in any way gain or 
lose financially from the publication of this manuscript, either now or in the 
future?  
 
3.  Do you hold or are you currently applying for any patents  relating to the content 
of the manuscript?  
 
4.  Have you received reimbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5.  Do you have any other financial competing interests?  
 
6.  Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no compet ing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
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