PONE-D-21-20356

COVID-19 associated hospitalization and mortality in 571 patients with fibromyalgia - A population-based study

PLOS ONE

Dear Dr. Amital,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

# reviewer 1

Mor Amital et al in their manuscript entitled "COVID-19 associated hospitalization and mortality in 571 patients with fibromyalgia - A population-based study" tried to explore where the presence of fibromyalgia (FM) are associated with

a severe COVID-19 disease course.

However, there are some major concerns.

1.   I am confused about the outcome of this research. In the Method part, authors defined the “COVID-19 hospitalization” as the outcome, whereas from the title or conclusion, we can see “COVID-19 hospitalization and/or related mortality” was the outcome. Please clarify this point.

2.   As authors mentioned “We also formed a control group, electing for each FM patient two controls adjusted by age, gender and geographic location”, how did you make the match? Where did you choose the controls?

3.   Please check whether the variables “hospitalization duration” and “COVID-19 duration” follows normal distribution. If not, it is not proper to use mean (SD) to describe it.

4.   Authors conducted different multivariable logistic regressions in FM patients and controls, respectively. I think performing multivariable logistic regressions in the whole cohort (combining the FM patients and controls ) would be preferable.

# reviewer 2

Amital et al in their manuscript entitled "COVID-19 associated hospitalization and mortality in 571 patients with fibromyalgia - A population-based study" tried to find the association of fibromyalgia and COVID-19 hospitalization or related mortality in the COVID-19 patients. It is an interesting study. However, there are some major concerns.

1.     In the introduction, it is not clear that the COVID-19 patients also experienced fibromyalgia.

2.     Please explain why the fibromyalgia and control group were chosen as 1 to 2 rather than 1 to 1.    

3.     Amital at al please clarify how the control group was chosen since the patients also have similar conditions, e.g. rheumatoid arthritis, as you mentioned fibromyalgia was common rheumatology condition. What was the exclusion criteria for FM and control group?

4.     What were the levels of the inflammatory biomarkers, e.g. IL-6, IL-8, CRP…?

5.     Please define the abbreviates first, e.g. HCV and use accurate term “peripheral arterial disease” rather than “peripheral heart disease”.

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Academic Editor

PLOS ONE

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COVID-19 associated hospitalization in 571 patients with fibromyalgia - A population-based study

PONE-D-21-20356R1

Dear Dr. Amital,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Ying-Mei Feng

Academic Editor

PLOS ONE