Review for 10.1186/s12876-025-04182-6 (2025)

Title: Socioeconomic Burden of Patients Hospitalized for Fecal Impaction: A Nationwide
Retrospective Observational Study
Version: 0 Date: 22 Apr 2025
Reviewer's report:
This paper is an important study showing that fecal impaction (FI) in the elderly can be a
significant socioeconomic burden. I should be grateful if you could consider my comments
shown below when you revise your paper.
Major comments
Question 1. Title
The paper concludes that the mortality and socioeconomic burden of FI is high. However,
this study does not represent the mortality and socioeconomic burden of FI in Japan, since
the number of DPC beds (approximately 500,000) is about 1/3 of all beds (approximately
1.5 million) in Japan. Most FI is likely to be safely treated in outpatient settings or nursing
homes. Therefore, the title of this paper, “Socioeconomic Burden Related to Fecal Impaction: A
Nationwide Retrospective Observational Study,” is misleading to readers. The study population
consisted of patients with severe FI who had to be hospitalized in tertiary medical center.
Therefore, to avoid misunderstanding, it would be better to change the title to the following as
an example: “Socioeconomic Burden of patients hospitalized for fecal impaction: A Nationwide
Retrospective Observational Study.”
Question 2. Background
You state the following: A recent systematic review reported that 43.5% of patients diagnosed
with FI were aged 65 years or older [1]. The mortality rate in patients aged 65 years or older
can reach as high as 32.0% [1]. The incidence of FI in the elderly over 65 years of age is not
low; therefore, if 32% of them die, the global population over 65 years of age will rapidly
decline. Reference No. 1 cited here included patients with complications secondary to FI, such
as colitis, perforation, fistula, bleeding, and megacolon, and excluded patients with FI without
complication. Therefore, it would be better to add to the above statement the phrase “patients
with any complication secondary to FI,” for example. Otherwise, it will mislead many readers.
Question 3. Methods: Measurements
The description “ICD-10 codes for four primary and concurrent diagnoses” may not be
understood by non-Japanese doctors. This is because readers outside Japan are unaware of the
fact that Japanese DPC lists up to four diseases that affected patient management during the
hospitalization period and if more than four, select the four that had the greatest impact. The
question here is whether or not FI was the primary diagnosis among the four diagnoses. If you
included cases in which K564 was not the primary diagnosis, you should state in the eligibility
criteria that “cases with ICD-10 code K564 among the four primary and concurrent diagnoses
were included in the study” for example. Then, the three primary and concurrent diagnoses other
than FI should be added to the patient background table.
Question 4. Methods: Definitions and Outcomes
You state that FI was defined using ICD-10 code K564. However, ICD-10 code K564 in the
Japanese electronic medical record may include colonic impaction, intestinal calculi, and fecal
ileus in addition to FI (http://www.byomei.org/) ? If so, this study would include more severe
cases than common rectal fecal impaction and this should be noted in the eligibility criteria
section.
Question 5. Results: Treatments
According to Reference No. 24, elderly patients with FI are usually treated with manual
extraction, retrograde lavage (enema), or intensive use of laxatives. However, table 2 shows that
treatment for FI was given in only 39.3% of cases. For the remaining 60% of patients, what
method was used to remove the fecal mass?
In fact, it probably included many patients whose primary diagnosis was other than FI. In light
of the above, the Results or Discussion should explain why only 40% of patients received
disimpaction. If the reason is not clear from the DPC data alone, then it should be added to the
limitations.
Question 6. Results: Risk Factors for Mortality
You state that sepsis had the largest impact on in-hospital mortality rates. Since sepsis due to
FI is very rare in general practice, the mechanism leading from FI to sepsis should be described
in the results or discussion. In other words, whether the cause of sepsis is enteritis, perforation,
or bacterial translocation is of interest to the reader; if it is difficult to infer from the DPC data,
this should be added to the limitation.
Question 7. Discussion
You state that the mortality rate for FI was reported to be 21.9%–28.0% and could reach 32.0%
among older individuals [1,11]. However, Reference No. 1 cited here included patients with
complications secondary to FI, such as colitis, perforation, fistula, bleeding, and megacolon, and
excluded patients with FI without complication. Reference No. 11 is also a study of FI patients
presenting to the emergency department and excludes outpatient. In other words, the overall
mortality rate of FI should be much lower, and these high mortality data are misleading to the
reader. Therefore, the reasons for the high mortality (patient background or eligibility criteria)
should be provided here.
Question 8. Discussion
In light of Q1-7 above, the following statements are not persuasive: Given that our analysis
utilized nationwide data, our findings could provide the most valid and reliable estimates of
mortality rates for FI.
Question 9. Discussion
In the limitations, you have given a bit of an excuse related to Q1-7 above, but you need to be
more specific in order to avoid misinterpretation by the reader.