Corresponding Author:
Mohamad Bashir, MD, PhD, MRCS
Department of Vascular and Endovascular Surgery
Royal Blackburn Teaching Hospital
Haslingden Rd, Blackburn BB23HH, UK
Email: drmbashir@mail.com
Keywords: Meta-analysis, publication bias, Meta-regression,
aorta, frozen elephant trunk
To the Editor: We appreciate Wu and
colleagues’1 letter
submitted and entailed few critical points regarding the published
meta-analysis data and the credibility of conclusions perceived. Thus,
and in an attempt to demystify the confusion, we summarized few pointers
that Wu et al. need to consider in interpretation of meta-analysis:
- It’s not a surprisingly practice that we pursue a rather scientific
and stringent execution of thoughts and quality metric articles’
assessment for clarity, quality, quantity, and critical appraisal
components. Our extensive experience in publishing systematic reviews
leans stringent data requirements to substantiate the objectives that
had to be mandated. In contrary to what Wu et
al1 perceived,
publication bias is not a practice we follow to achieve desired
outcomes. As such cognitive selective steps are adhered to and
following quality metrics from published articles observed. The
frequency of observational data declaring statistical significance in
dire surgical experience as in Type A dissection is a reflection of
current trends and practices. As such, it would be seemingly positive
that publication bias is an unequivocal mannerism in constructing a
rather niche meta-analysis. We have undoubtedly maintained a stream of
thought to exclude any overlapped/duplicated population from the same
institutions per se, alluding to extractable data for patients with
isolated acute type A aortic dissection undergoing total arch
replacement with frozen elephant trunk (FET).
Concerns highlighted on this entity can easily be slotted into the
following methodological nature of all meta-analyses. In concluding
this section, as with all meta-analysis we published, we’ve
implemented a dual-reviewer process including abstract screening upon
selection of relevant studies as alluded to and
aforementioned.2
- We follow a rather constructive approach of heteroscedasticity to
overcome culpable heterogeneity in all meta-analysis we conducted. The
idea to give small weighted regression to observation associated with
higher variances to minimize potential residual is a substantial
practice we follow. As such postoperative stroke and SCI were found to
be I2= 63.93% and I2= 19.56%,
respectively; however, we did not find any significant effect of
subgroup analyses on the heterogeneity of pooled estimation of
postoperative stroke. Our objectives and primary focus were on
neurological outcomes, and as such, we performed a meta-regression
analysis for those observed outcomes with variable heterogeneity.
Additionally, there are many confounding factors that we were not able
to extract from these observational studies to explore potential
factors affecting the final meta-analysis. This is the limitation of
the majority of a meta-analysis conducted. The lack of stringent
criteria for randomization and the overwhelming unethical platform to
conduct such studies which surely Wu et
al1 would agree yield
a rather homoscedasticity allowing a sequence of random variables to
have a finite variance with time linear function. Compounding this
notion is the lack of randomized clinical trials for FET procedure and
the paucity of standard presentation of study results and baseline
characteristics precluded us from a comprehensive exploration of
confounding factors.
- It’s our practice that standardization and protocolization in
meta-analysis are pursued, thus, we tried to extract data from the
main text of the articles, however, we stumbled across different
challenges that culpably allowed us to use a common denominator i.e.
reading full-text, we used method section and the affiliation of the
ethics committee for assigning the location of study institution,
neither database affiliation and nor corresponding affiliations were a
streamed thought amongst all contributors of this analysis. Moreover,
Sun and colleagues,3in their method section of their study had assigned “patients
underwent surgical treatment at Fuwai Hospital, Beijing, China”.
Given this notion, we considered it as an affiliated study with Fuwai
Hospital. It might be recommended that the adherence to the standards
of the ethics committee and outcome reporting studies with a defined
affiliation of the population would be imperative aiding future
researchers and misleading endeavors. The large number of patients
undergoing the FET procedure in Anzhen hospital has resulted in the
publication of many articles with overlapped or even duplicated
populations per se.
- We have performed a univariate meta-regression to find a linear
relationship between neurological outcomes and the utmost important
variable associated with these events. Due to lack of data in the
majority of studies and small sample size of included studies into the
regression model, it is justifiable that implementation of a
multivariate meta-regression analysis would be realistically
unjustified and would render the desired characteristic and outcomes
to be over-inflated disturbing our attempt to generate meaningful
analysis in this evidence synthesis and precision healthcare era.