Skip to main content

Response to: Low gestational age is associated with less anastomotic complications after open primary repair of esophageal atresia with tracheoesophgeal fistula. BMC Paediatric 2020; 20:267

Peer Review reports

Dear Editor,

We read with interest Dingermann et al.’s recent paper Low gestational age is associated with less anastomotic complications after open primary repair of esophageal atresia with tracheoesophageal fistula. The authors and their units should be commended on achieving zero operative mortality and a remarkably low complication rate in a cohort including some very small babies. The finding of a decreased risk of complications in patients born at a lower gestational age, a group traditionally felt to be at higher risk, is a surprising one with no obvious biologically plausible explanation and therefore warrants further scrutiny [1, 2]. We have some concerns over the way the data have been processed and analysed and consequently feel the conclusions drawn should be reconsidered.

The first decision made that is questionable is the decision to set the cut off at 34 weeks gestational age for the two groups. This is surprising as the usually accepted definition of prematurity is a baby born at under 37 completed weeks of gestation. References are given to support the choice of a 34-week cut off but one of these is from an ethics textbook [3] and another, concerning the administration of maternal steroids to promote fetal lung maturation, itself uses 37 weeks as the definition of prematurity [4]. As the median gestational age in the cohort presented was 37 weeks, using this widely accepted definition of “preterm” would have given two equal groups to compare. Insufficient data is given in the paper to make a definitive assessment but it appears from Fig. 2 that using 37 weeks would give roughly equal allocations of complications to the term and preterm groups.

The key analysis comparing the occurrence of complications (anastomotic leak, recurrent fistula and anastomotic stricture) in each group (< 34 weeks and ≥ 34 weeks gestation) has been performed in a highly unusual manner. These are clearly categorical data (yes/no for the occurrence of each complication) and we would expect the analysis to be with the Chi-squared or Fisher’s Exact Test if numbers were small. Instead, an unpaired t-test has been used, apparently on the proportions of complications in each group. How a range of proportions with the mean and standard deviation needed to carry out a t-test have been generated for each group is unclear. When the analysis is performed using more standard statistical methods, the findings are rather different. Using a Fisher’s Exact Test and a threshold of P < 0.05 to re-run the analysis for Table 3, there was no statistically significant difference seen between the two groups for any of the reported surgical complications (Table 3: amended). Unsurprisingly, there were statistically significant differences in the incidence of respiratory distress syndrome and intraventricular haemorrhage between those under 34 weeks gestation and those over, [4, 5], supporting the use of Fisher’s Exact Test.

Table 3 (amended): Postoperative outcome after primary esophageal anastomosis for eophageal atresia with distal tracheoesophageal fistula

A subsequent analysis (Fig. 2) again uses percentages of patients experiencing complications at each completed week of gestational age and a correlation coefficient has been calculated. This method seems unsound for two reasons. The first is that the proportions (percentages) used are the sum of all complications. Given that the occurrence of an anastomotic leak increases the risk of both a recurrent fistula and anastomotic stricture, this is likely to represent double or even triple counting of the same complications. Secondly, these are again categorical events and so trying to construct a correlation line is an inappropriate statistical method.

Lastly, the authors note a significant difference between the two groups in the presence of associated anomalies in addition to the esophageal atresia and trachea-esophageal fistula. These associated anomalies are known to be linked with an increased incidence of complications [6, 7]. Despite this, no multi-variate analysis has been attempted, as a minimum a two-factor regression model would be needed although we acknowledge the limitations of these models with small numbers.

On reading the reviewers comments, which BMC Pediatrics commendably make available on line, neither peer reviewer comments on the statistical methods employed although both state in their review submissions “I am able to assess the statistics”. It would seem that their review and assessment was insufficiently robust to ensure the veracity of what has been published. The data presented in the paper do not support the conclusion that low gestational age is associated with less anastomotic complications after open primary repair of esophageal atresia.

Availability of data and materials

All data generated or analysed during this study are included in this published article.

References

  1. 1.

    Pierro A, et al. Outcomes of esophageal atresia/tracheosophageal fistula in extremely low birth weight neonates (<1000 grams). Pediatric Surg Int. 2016;32(1):83–8.

    Article  Google Scholar 

  2. 2.

    Malakounides G, et al. Esophageal Atresia. Improved Outcome in High-Risk Groups Revisited. Eur J Pediatric Surg. 2016;26(3):227–31.

    Article  Google Scholar 

  3. 3.

    Fleischmann AR. Pediatric Ethics: Protecting the Interests of Children: Oxford University press; 2016

  4. 4.

    Committee Opinion No. 713. Antenatal corticosteroid therapy for fetal maturation. Obstet Gynecol. 2017;130(2):e102-109.

    Article  Google Scholar 

  5. 5.

    Platt M. Outcomes in preterm infants. Public Health. 2014;128(5):399–403.

    CAS  Article  Google Scholar 

  6. 6.

    Leonard H, et al. The influence of congenital heart disease on survival of infants with oesophageal atresia. Arch Dis Child Fetal Neonatal Ed. 2001;85(3):F204-206.

    CAS  Article  Google Scholar 

  7. 7.

    Pernilla, et al. Congenital Heart Disease and Its Impact on the Development of Anastomotic Strictures after Reconstruction of Esophageal Atresia. Gastroenterol Res Pract. 2018;2018:6021014.

    Google Scholar 

Download references

Funding

Not applicable.

Author information

Affiliations

Authors

Contributions

VC and IY had equal input into review of the manuscript, re-analysis of the data and write-up and approval of final article.

Corresponding author

Correspondence to V. Coles.

Ethics declarations

Ethics approval

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Coles, V., Yardley, I. Response to: Low gestational age is associated with less anastomotic complications after open primary repair of esophageal atresia with tracheoesophgeal fistula. BMC Paediatric 2020; 20:267. BMC Pediatr 21, 425 (2021). https://doi.org/10.1186/s12887-021-02900-z

Download citation