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Correspondence on ‘prevalence and clinical outcomes of COVID-19 in patients with autoimmune diseases: a systematic review and meta-analysis’
  1. Jiyuan Shi1,
  2. Ya Gao1,
  3. Lili Zhang2,
  4. Yang Zhao2,
  5. Jianguo Xu1,
  6. Jinhui Tian1
  1. 1 Evidence-Based Medicine Center, Lanzhou University, Lanzhou, Gansu, China
  2. 2 School of nursing, Southern Medical University, Guangzhou, Guangdong, China
  1. Correspondence to Professor Jinhui Tian, Lanzhou University, Lanzhou 730000, China; 15038059737{at}

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We read with great interest the article by Akiyama et al,1 which evaluated the prevalence and clinical outcomes of COVID-19 in patients with autoimmune diseases. This important work showed that patients with autoimmune diseases had an increased risk of COVID-19, primarily attributed to glucocorticoid use. However, several issues that may affect the results should be noted.

First, it was unclear what type of studies this study included, we observed that the expression of ‘observational studies and case–control studies’ has been mentioned many times, but as far as we know, case–controls belongs to the category of observational studies. We hope that authors can clarify the criteria for inclusion of study types. For questions of prevalence, cross-sectional studies using probabilistic random samples conducted in the relevant geographical setting or location are the most appropriate study design, whereas questions of incidence are best answered in cohort studies.2 Distinguishing between different research designs is not only helpful for authors to choose the correct risk of bias (RoB) tool, but also facilitates sensitivity analysis and subgroup analysis for different research designs to explain the source of heterogeneity.3 4

Second, the RoB assessment is one of the key steps in the assessment of quality of evidence.3 We are pleased to see that the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used to assess evidence, however, GRADE was designed to assess the overall quality of evidence, and cannot replace the RoB for individual studies.5 It is worth mentioning that a number of tools already developed for assessing the quality of various study designs, unfortunately, we did not find this study described methods used for assessing RoB of individual studies.2 3 6

Third, according to the recommendation by GRADE working group, explicit consideration should be given to each of the GRADE criteria for determining the direction and strength of a recommendation or decision, however, the criteria for evaluating GRADE were not clear described in the method section (eg, how to defined evidence as high, moderate, low or very low, and whether assessed by two reviewers independently).5 Moreover, we observed that the starting level of evidence was high, as far as we know, the initial evidence quality of observational research is usually at a low level. To upgrade the level of evidence quality, author must first consider the scientific and rigorous research methods, and consider the impact of five downgrading factors.5 Through the evaluation of the included studies, we believe that the process of grading the quality of the evidence should be more cautious. It is worth reminding that GRADE approach is very limited in its applicability to incidence/prevalence studies, we do not know how the author overcomes this limitation.7

Forth, we observed multiple outcome assessment were presented in the article (eg, prevalence, hospitalisation, mechanical or non-invasive ventilation and death). GRADE evaluation should be performed on each outcome separately, however, only two outcomes of the GRADE assessment were reported.5

Fifth, we recommend that author should present full electronic search strategy for at least one database as online supplemental data, including any limits used, such that it could be repeated.8 Furthermore, the author mentioned that they also searched medRxiv, as we all know, preprints are preliminary reports of work that have not been certified by peer review, but we did not find the author’s description of how to evaluate the quality of these articles. Since heterogeneity is generally observed in the results, we suggest that sensitivity analysis could be performed for preprints.

Sixth, this study only searched four English-language databases, however, in the early days of the COVID-19 epidemic, most of the evidence came from China, Korea, Japan, France and Italy, indicating that a considerable number of studies were published in non-English. The author mentioned that no geographical or language restrictions were imposed, unfortunately, few articles published in non-English languages were included, which may lead to important biases in the retrieved studies. Given this study was not limited to local or national, but a global level, authors should at least discuss the potential bias in the section on language limitations.

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  • Contributors JS, YG, YZ, JX and JT formulated the manuscript first draft. JT and LZ read the manuscript critically.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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