Dear Editor,
We read with great interest the article by Xu Qiancheng and colleagues (Volume 95) (Qiancheng et al., 2020). The authors compared clinical courses and outcomes between pregnant and non-pregnant women with COVID-19 and assessed the vertical transmission potential of COVID-19 in pregnancy. The report from authors on pregnant and neonatal cases is commendable and sheds light on this infection in a vulnerable group. However, we are concerned about a specific aspect of this study.
In the Data declaration section, the authors stated:
at the time of submission of the manuscript (March 30, 2020), no studies were identified as including data from this study. During the revision period (April 17–21, 2020), an online correspondence was published on April 18 in the New England Journal of Medicine, which reported 118 pregnant women with COVID-19 in Wuhan, among which 11 cases were from the same hospital as our study.
This clarification made by the authors is good practice, as duplication can give a potentially biased picture. However, we believe that there may be more than 11 duplicates of cases of COVID-19 in this article. There are several reasons for our skepticism:
First, we found that another two articles were reported by doctors at the same hospital (Wang et al., 2020, Wu et al., 2020). As we thoroughly examined the details of these three studies, we are very surprised to find that the periods of recruitment overlapped.
Second, at least one pregnant woman or neonate had identical characteristics (e.g., gestational age at delivery, maternal age, complications, delivery mode, birth weight). Of all three articles, including one set of twins, two reported that three pregnant women terminated pregnancy in the first trimester.
Third, it is worth noting that the corresponding author is the same person in two of the three articles. The three papers were received and published on very similar dates.
Several concerns about duplicate reporting of COVID-19 cases have been previously described (Bauchner et al., 2020, Mofenson et al., 2020). As mentioned above, reporting duplicates in different articles creates an inaccurate scientific record, may introduce significant bias into a systematic review, and may affect understanding of the disease and its epidemiology. We suggest that when a hospital has published the cases more than once, if the periods of recruitment overlapped, only the paper with the biggest data be included in a systematic review, to minimize the possibility of double counting. Thus, it is imperative for authors to identify if any patients in any submitted manuscript have been reported in any previous submissions or publications.
Author contribution
All authors equally contributed to the work and approved the final version.
Ethical approval
Not applicable.
Funding source
None.
Conflict of interest
We declare no competing interests.
References
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