Delirium after Spinal Surgery: A Pilot Study of Electroencephalography Signals from a Wearable Device
Round 1
Reviewer 1 Report
The topic of the paper, using EEG to evaluate delirium is very interesting. However, there were serious methodological and ethical issues with this paper which had me inclined to reject it. However, if they can be addressed with major revisions this paper would be a great read. Below are my comments.
The device being used is not one I am familiar with. I searched online but found limited information. I have concerns over the accuracy of the device. If the authors have any references that can be included in their methods on the quality of the device, it would satisfy my concern.
Lines 111-122
Need to specify more on the conditions the data was collected here. Were they sitting? Eyes-open or closed? Length of the recording? Room conditions?
Statistical Analysis
The statistics are underwhelming and one of my major concerns for this paper. The choice is not explained, but perhaps the authors can provide some clarity. A Mann-Whitney U (aka Wilcoxon Rank Sum) Test is a non-parametric test. Are we to make the assumption that the data failed Levene's or were not normally distributed? Given the data type, I am a bit shocked either an ANOVA or mixed model ANOVA in the form of (y ~ x + 1|id) where id is a random effect for subject differences was not used.
Table 1. Please report age range as well.
There are some ethical consideration here, which I will leave up to the editor. But the authors acknowledge the company who fabricated the EEG (SOSO H&C) analyzed their data. There is a significant conflict of interest here if the company was not blinded to the conditions. If there were, this needs to be explicitly stated in the methods.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Thank you very much for this interesting study. I just have a few comments on the setting: To my knowledge RASS is not a delirium assessment tool. It could be used to evaluate if a patient is in a state of delirium-test ability as most delirium tests include a response of some kind of the patient. For ICU patients the CAM-ICU has been developed and validated. Therefore, you should consider to change the statements about delirium detection on ICU and the normal ward. A hypoactive delirium could also be detected in patients if appropriate questionnaires are used.
It would be very interesting to know how often the patients have been tested for postoperative delirium in the first week and when? Which test tool was used? If there was only one POD test done within one week after surgery it might be possible, depending on the time-point of the testing, that events of POD were missed in some patients as this adverse event usually occurs on day 1 to 5 after surgery and does not necessarily last for more than one day. So maybe you should provide a more precise description of the delirium testing as this is a key component of your study.
It would be interesting to know which form of delirium were present and how long the postoperative delirium lasted in the patient and if this made a difference in the EEGs.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
