Review for 10.1186/s12876-021-01858-7 (2021)

Reviewer’s report
Title: 
Normalisation of the psychometric encephalopathy score within the
Cameroonian population
Version: 
0 
Date: 
31 Jan 2021
Reviewer's report:
The paper by Larissa Pessidjo Djomatcho reports the
standardization/parameterization of the tests composing the porto-systemic
encephalopathy battery (PSE battery) and the calculation of the psychometric
hepatic encephalopathy score (PHES) in 102 healthy volunteers (probably heath
personnel) and the application of the procedure to a group of patients with
cirrhosis. In these subjects, an altered PHES was related to age and education
and to a trend for high Child-Pugh score and MELD.
The paper is clear; however, I am concerned of some relevant issues. Thus, I
would like to provide constructive criticism, so that a good standardization can
be obtained.
Major criticism
1) The population used for the standardization is reasonably composed by health
personnel (Persons present at the hospital for non-medical reasons were selected
as healthy volunteers), biased for young age and good education. Thus, is this
population representative of the general Cameroonian population? Many doubts
arise. The authors should report which is the demographic composition of people
in Cameroon and its education. A much more way to select a representative
group of healthy people is to test healthy relatives (wife/husband, sisters,
brothers, parents and sons/daughters, friends of cirrhotic patients). Otherwise, a
random sample from Cameroonian population (both from rural and urban areas)
stratified by age and education should be enrolled. The former technique is easier
and can be easily collected by the authors either to prove that their
standardization is realistic or to re-parameterized the model. 
2) The years of education of the patients who were supposed to have MHE is
7.9±2.8. Thus, many of them have less than 5 years of education or are illiterate.
The possibility to test such patients by paper and pencil test is questionable,
since they are not familiar either with paper and pencil. 
If the authors want to
extend their useful research, they may try to add a standardization for the animal
naming test [1], using local language. Familiarity with animal names may be
much more diffused than the one with pencil.
3) The lack of relationship with cirrhosis severity and the link with age and
education seem me evidence that the standardization sample is inadequate for the
general population. 
4) Poor psychometric performance is not evidence of MHE, if other causes of
poor psychometric performance are not excluded. 
5) The discussion reports results, thus it is formally unfit. Provided new data are
added, it should be re-written in the proper style of a discussion.
6) The correlation of the PHES calculated by the Spanish standardization and the
one proposed by the authors is poor. Which are the tests that fit well and those
that do not fit well?
Minor criticism
1) Line 20: the PHES is not a series of tests. It is the score of the porto-systemic
encephalopathy battery (PSE battery), which is compose by 5 psychometrical
tests.
2) The evaluation of LTT was done according to the formula LTT= (1+
LTTe/100) xLTTt. This is not the original way[2], but the one firstly adopted by
the Italian standardization [3] to solve the problem of the inverse relationship
between speed and accuracy. However, the paper is not cited.
3) In supplementary material, an example of calculation of the Z score for each
test and of the PHES would help the reader.
References
1. Campagna, F.; Montagnese, S.; Ridola, L.; Senzolo, M.; Schiff, S.; De Rui,
M.; Pasquale, C.; Nardelli, S.; Pentassuglio, I.; Merkel, C.; et al. The animal
naming test: An easy tool for the assessment of hepatic encephalopathy.
Hepatology 2017, 66, 198-208, doi:10.1002/hep.29146.
2. Schomerus, H.; Hamster, W. Neuropsychological Aspects of Portal-Systemic
Encephalopathy. Metab. Brain Dis. 1998, 13, 361-377.
3. Amodio, P.; Campagna, F.; Olianas, S.; Iannizzi, P.; Mapelli, D.; Penzo, M.;
Angeli, P.; Gatta, A. Detection of minimal hepatic encephalopathy:
Normalization and optimization of the Psychometric Hepatic Encephalopathy
Score. A neuropsychological and quantified EEG study. J. Hepatol. 2008, 49,
346-353.
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
No
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes