Reviewer Comments

Reviewer comments

The authors have carried out a meticulous review of the five meta-analyses, all published in 2012–13, comparing cardiotocography plus ECG ST interval analysis (CTG+ST) vs. CTG alone. Substantial weaknesses were identified in all five meta-analyses. The STAN concept is based on a biologically sound theory and ought to have the potential to improve fetal monitoring in labor. Doubts such as irregularities in the primary randomized controlled trial data and changing operating instructions have, however, disturbed its implementation in clinical practice. This article reinforces my impression that a proper evaluation of STAN remains to be done. Hopefully, the scientific community can unite and perform a new meta-analysis including revised results from previous randomized controlled trials and from the awaited new American randomized controlled trial. Focus should be on important outcome measures such as perinatal mortality and essential morbidity.

Ove Axelsson

Department of Obstetrics and Gynecology, Uppsala University, Uppsala, Sweden

Reviewer comments

The authors performed a critical appraisal of the five meta-analyses published in 2012–13 of CTG+ST interval analysis (CTG+ST). Importantly, none of the meta-analyses included complete and relevant data from all five randomized controlled trials published so far. After considering the weaknesses, their new meta-analysis showed that CTG+ST monitoring significantly reduced fetal scalp blood sampling usage, total operative delivery rate, and metabolic acidosis rate. This is an important message based on revised meta-analysis.

The conclusion statement focuses on the current state of the art, but does not take a wider perspective. The authors focus on the problem of the five meta-analyses and differences between the meta-analyses and associated biases. However, the reader is still missing important key messages. Some key messages are listed. However, the following key messages are missing: CTG+ST for fetal surveillance requires an intensive and continuous training program, and cost-effectiveness or cost-efficacy of the CTG+ST analysis has not been extensively evaluated. Such cost–benefit analyses are important, particularly now when the use of this intervention is rapidly expanding. The authors do not comment on the health economic aspects nor do they critically appraise health economic analyses of CTG+ST.

Jorma Paavonen

Department of Obstetrics and Gynecology, Helsinki University Hospital, Helsinki, Finland

Reviewer comments

The study is a monograph, discussing five published systematic reviews with meta-analyses. The aim of the systematic reviews was to assess the effect of fetal surveillance with cardiotocography plus ECG+STAN®. There are six authors on the monograph. Two of the authors are medical advisers paid by the company producing the STAN equipment, two more also have a conflict situation, and two report no conflicts of interest. It is important to perform critical appraisals, and the authors point to several interesting differences and heterogeneity across the included randomized controlled trials. The authors have also provided new meta-analyses on the outcomes “Fetal scalp blood sampling”, “Total operative delivery”, “Metabolic acidosis”, and “Encephalopathy stage > 2” according to Sarnat & Sarnat.

The authors think that the Plymouth study should be included in the meta-analyses, but the arguments are unclear. The Plymouth study evaluates an older version of the technology, where analog signals (not digital signals, as in newer versions) were used. This technology is no longer used, and it is appropriate to exclude the study from the meta-analyses. Alternatively, meta-analyses can be carried out with and without the Plymouth trial and the pros and cons can be discussed. Different technologies across the studies introduce heterogeneity. The authors argue that the French study should be excluded because of the inclusion of women with abnormal CTG tracings in labor and meconium-stained amniotic fluid, which in many cases represented violation of the STAN guidelines, but there might be a proportion of cases in the other randomized controlled trials included on similar premises. The authors do not provide any conclusions of clinical impact. Is the addition of STAN beneficial for the woman and her infant?

Pål Øian

Department of Obstetrics and Gynecology, University of Northern Norway, Tromsø, Norway