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Thanks for making the requested changes.
[# PeerJ Staff Note - this decision was reviewed and approved by Jun Chen, a PeerJ Section Editor covering this Section #]
The reviewer has requested that you use a different method for part of the analysis.
The introduction is unambiguous and sufficient literatures were cited.
Adequately written. ALthough univariate local spatial autocorrelation was used, this does not really provide any useful information regarding the spatial interaction between the outcome and covariates examined in the study. The authors should include bivariate spatial autocorrelation (e.g. Bivariate Moran's Index) to measure the spatial interaction between the outcome and covariates.
Addition of bivariate spatial autocorrelation will add credence to the spatial analysis
This is a much imporved version of the manuscript. I will recommend this manuacript for publication after minor revision.
Apologies for the delay in sending this decision to you. It was due to COVID-19 impacting on the workload at our institution.
[# PeerJ Staff Note: Please ensure that all review comments are addressed in a rebuttal letter and any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate. It is a common mistake to address reviewer questions in the rebuttal letter but not in the revised manuscript. If a reviewer raised a question then your readers will probably have the same question so you should ensure that the manuscript can stand alone without the rebuttal letter. Directions on how to prepare a rebuttal letter can be found at: https://peerj.com/benefits/academic-rebuttal-letters/ #]
The manuscript by Al-Ahmadi et al is timely given the current outbreak of coronavirus disease (COVID-19).
The introduction is well written, though too long and the literature cited are adequately. There are few grammatical errors here and there, eg. None-healthcare workers should be non-healthcare workers, line 325 “over died”.
The major strength of this study (as stated by the title and objective) should be the use of spatial analysis accounting for regional risk factors. However, the authors almost failed to capitalize on this.
The major aim of this study was “to estimate the survival rates and hazard ratios of MERS-CoV mortality for 14- and 45-day post-symptom periods and to assess spatial variations by both the region in Saudi Arabia and the patient characteristics between 2012 and 2019.“
There is no single spatial component in the survival analysis described in the methods section. No regional/provincial level risk factors incorporated in the model described.
The spatial part of the results provided descriptive summaries of MERS-CoV across the regions. On line 241, the authors claimed the spatial variations were assessed but did not provide any detail information on the technique(s) used in the methods. What I can deduce from their findings on Table 2 & 3 is that either the authors conducted a separate survival analysis for each of the regions, thus, assuming no spatial dependencies or used region as interaction in the model. The authors use appropriate spatial survival analysis and account for regional risk factors as they mentioned is one of the drawbacks of previous studies.
Given that spatial variability is one of the main objectives of this said, the authors almost failed to discuss this aspect of their study in the discussion and conclusion.
Abstract:
Line 18-20: There is no mention of spatial analysis/variability.
Materials and Methods
Line 120-138: The authors mentioned one of the previous studies that used spatial modeling approach did not consider province level risk factors. One would have expect that this study will include such risk factors that are lacking in previous studies.
Check through for few grammatical errors
Sufficient literature references were given.
Methods didn't describe with sufficient details but research question was well defined, relevant and meaningful.
The methods are not novel but the paper addressed the gap of not modeling the multivariate risk factors.
The paper addressed the gap in the literature in terms of modeling the multivariate risk factors for MERS-CoV using multivariate analysis to investigate variations between mortality risk factors in different geographic areas of Saudi Arabia. It is an interesting applied paper. However, I did not see in the paper on how they addressed the geographic variation, For example, adding into the model structured and unstructured random effects to take into account the spatial correlation between the regions (or provinces) and noise in the data, respectively. Here are my specific comments.
1. It would be good to mention on how the authors handle the spatial correlation between the regions (or Provinces)
2. It would be great if the authors jointly models the risk at both Province and regional level simultaneously to borrow information from the province to the regional level. As such, it would be interesting if they displayed the risk variations across the province and regional levels.
3. In the introduction section, page 6, line 65-69 is not clear. It may be reworded as The severity of
illness such as for patients receiving vasopressor therapy (Almekhlafi et al. 2016), requiring invasive mechanical ventilation (Almekhlafi et al. 2016), and with higher chest radiographic scores (Das et al. 2015) are also associated with the risk for mortality resulting from MERS-CoV (Adegboye et al.2017; Ahmed 2017a).
4. In the introduction section, page 6, line 72-72, is not clear. It may be reworded as:
Researchers found that being healthcare workers (HCWs) is associated with higher mortality rates (Alsahafi & Cheng 2016), but other studies conversely linked being none-healthcare workers (none-HCWs) with higher mortality rates (Adegboye et al. 2017; Ahmed 2017b; Ahmed 2018; Rivers et al. 2016; Sha et al. 2017).
5. In the introduction section, page 6, line 83, 4-5 should be 4-5 days.
6. In the introduction section, page 7, line 92, it says `However, the virus..' but it doesn't look this sentence contradicts with the previous one. Using the phrase `However ' is not clear for me.
7. On page 8, line 158-159, it says `However, the log-rank test delivers a statistical, but not clinical, appraisal of the factors’ effects (Bradburn et al. 2003). Thus, the Cox proportional-hazards (CPH) model was applied...'. What do you mean by log-rank test delivers a statistical but not clinical appraisal of the factors effect? Does it mean CPH delivers a statistical but not clinical factors effect?
8. On page 9, line 194-195, it says `A lower mortality rate was found among those exposed to camels compared to those not exposed' . This looks unexpected result. Can the authors provide a justification why?
9. On page 12, line 319-323, it says `The univariate analysis showed that the hazard of
14- and 45-day mortality in MERS-CoV male patients is higher than that for females only at the
national level and in the Central and West regions. In contrast, the multivariate analysis could not..' Why it is higher in the Central and West regions but not in the other regions?
10. On Page 28, For Figure 2, it would be more interesting if you could replace it at 45-day instead of 14 day.
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