Bowel Lengthening Procedures in Children with Short Bowel Syndrome: A Systematic Review

Dear Editor.

I read the above-mentioned article with a great deal of interest.

The authors have performed extensive literature research to summarize and critically appraise the evidence of longitudinal intestinal lengthening and tailoring (LILT) and serial transverse enteroplasty (STEP) in children with SBS short bowel syndrome (SBS).[1] Despite their meticulous search strategy and adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement I am concerned the patient population was grossly overestimated due to double multiple-counting of the same patients reported in different included studies.

The authors themselves stated that several large pediatric centers publish frequently about their experience with pediatric SBS, and therefore, these centers may be overrepresented; however, they did not exclude articles of single centers concerning overlapping study periods to account for that possible sampling error.

The studies included in the pre- and post-STEP assessment are shown in [Fig. 1]. Several of the included studies were conducted at the same single centers. Since these studies have overlapping time periods, one can assume that individual patients are included in more than one study. The authors included multiple studies from single centers without clarification on how they were able to prevent possible double- or multiple-count of the same patients. Therefore, one must assume that this preventive process may not have happened. Furthermore, several of the included studies were performed at centers that participate in the STEP-Registry; however, a STEP-Registry report was also included in the systematic review performed.[2] This in turn leads again to possible double- or multiple-counting of individual patients (see [Fig. 1]). Data extraction by the authors showed 377 infants had undergone STEP. If only single studies and the studies with the longest study period of multiply-study centers were included, only 92 to 189 (without and with STEP-Registry report included) infants would have undergone STEP.

Fig. 1 Pre- and post-STEP. Gray: Single studies conducted at individual centers. Colored: Multiple studies conducted at the same center. Red: STEP-Registry report. Black outline: Studies of centers participating in the STEP-Registry.

The same possible methodical error may have occurred concerning studies of the pre- and post-LILT assessment as shown in [Fig. 2]. Data extraction by the authors showed 324 infants had undergone LILT. If only single studies and the studies with the longest study period of multiple-study centers were included, only 145 infants would have undergone LILT.

Fig. 2 Pre- and post-LILT. Gray: Single studies conducted at individual centers. Colored: Multiple studies conducted at the same center.

These restrictive calculations for the STEP and LILT patients would lead to a markedly reduced patient population in this systematic review, which in turn would mean if double- or multiple-counting had happened the drawn conclusions of this investigation would have been biased.

Especially in the field of SBS, where patient numbers are small and patients are hardly comparable, systematic reviews are of utmost importance, but if flawed could even more so jeopardize research efforts.

I would be grateful if the authors can comment if, and how, they were able to account for that possible double or multiple-counting of patients in the included studies with overlapping study periods.

Publication History

Article published online:
09 August 2023

• References

• 1 Nagelkerke SCJ, Poelgeest MYV, Wessel LM. et al. ERNICA Intestinal Failure Working Group. Bowel lengthening procedures in children with short bowel syndrome: a systematic review. Eur J Pediatr Surg 2022; 32 (04) 301-309
• 2 Jones BA, Hull MA, Potanos KM. et al. International STEP Data Registry. Report of 111 consecutive patients enrolled in the International Serial Transverse Enteroplasty (STEP) Data Registry: a retrospective observational study. J Am Coll Surg 2013; 216 (03) 438-446