Novel Assessment of Viscoelastic Skeletal Muscle Properties in Chronic Kidney Disease: Association with Physical Functioning
Round 1
Reviewer 1 Report
The authors of the manuscript entitled "Novel assessment of viscoelastic skeletal muscle properties in chronic kidney disease: association with physical functioning" demonstrated that using a novel handheld myotonometer is possible to identify a reduction in muscle tone, stiffness, and elasticity in CKD patients. However these viscoelastic muscle properties is not correlated with physical performance.
The major point I would like to address is that the control group is missing, even thought the authors are comparing the data with other selected studies. For instance, the authors are demonstrating that there are a reduction on the muscle tone and stiffness, which I can see it compared to the other studies, however I can not see a reduction on muscle elasticity using the MyotonPro. In fact, looking at the data I can see a increase in muscle elasticity.
In table 3, the authors associate men and women, BMI, age, eGFR, Hb and albumin to muscle properties. It would be nice if the authors could tabulate the raw data for each individual parameter.
In the 2.5 section, I did not find the p=.072 in the table. Please verify if the plotted data is correct.
Author Response
Comment: The major point I would like to address is that the control group is missing, even thought the authors are comparing the data with other selected studies. For instance, the authors are demonstrating that there are a reduction on the muscle tone and stiffness, which I can see it compared to the other studies, however I can not see a reduction on muscle elasticity using the MyotonPro. In fact, looking at the data I can see a increase in muscle elasticity.
Response: The reviewer is correct in that the value for elasticity is greater in our CKD cohort compared to the other populations in Table 2, and the arrows next to each value represent this. However, as indicated by the * in the footnote, a higher value indicates reduced elasticity. This is because the value is showing the logarithmic decrement as described in the Methods. As such, the interpretation we have made is correct.
Comment: In table 3, the authors associate men and women, BMI, age, eGFR, Hb and albumin to muscle properties. It would be nice if the authors could tabulate the raw data for each individual parameter.
Response: We are unclear with what the reviewer is requesting here sorry. The purpose of Table 3 is to show the demographic and clinical characteristics association with viscoelastic muscle properties.
Comment: In the 2.5 section, I did not find the p=.072 in the table. Please verify if the plotted data is correct.
Response: Apologies, this was a repetition (and error) of the result already stated above in the 1st sentence of this section. It can be removed here as the data above (P = .047 as in Table 5) is correct.
Reviewer 2 Report
This study evaluates the muscle properties of people with CKD, comparing them to historical controls and assessing associations with physical performance. Overall this manuscript is well written. I do have some confusion on statements and conclusions made as detailed below:
Section 2.2 and Table 2: Authors indicate that the conclusion is that muscle elasticity is decreased in CKD, however all comparison studies show lower levels of elasticity than what is found in the current study. It seems that the conclusion should be that CKD leads to increased elasticity. Can the authors explain their interpretation of the data?
Suggestion for Table 2: many of the comparison studies show the data of males and females separately, yet the current study has males and females combined. Have the authors considered displaying the data for the current study for males and females separately?
Section 2.5: The author states that all associations were insignificant, but there are clearly associations with P<0.05 in table 5 and mentioned in the text. Please explain your conclusions.
Author Response
Comment: Section 2.2 and Table 2: Authors indicate that the conclusion is that muscle elasticity is decreased in CKD, however all comparison studies show lower levels of elasticity than what is found in the current study. It seems that the conclusion should be that CKD leads to increased elasticity. Can the authors explain their interpretation of the data?
Response: Please see comment to R1.
Comment: Suggestion for Table 2: many of the comparison studies show the data of males and females separately, yet the current study has males and females combined. Have the authors considered displaying the data for the current study for males and females separately?
Response: Given the low number of the current study, we did not think this to be appropriate. Is likely that the lack of association we observed (and as discussed in the Discussion) is due to lack of power. Therefore, dividing the sample by sex may further dilute the data.
Comment: Section 2.5: The author states that all associations were insignificant, but there are clearly associations with P<0.05 in table 5 and mentioned in the text. Please explain your conclusions.
Response: Yes, apologies this was an error and we have removed this statement.
Round 2
Reviewer 1 Report
The authors answered all my questions. I believe it is an interesting subject to be published.
