EURURO Vol. 72 No. 2

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the study design and the analyses presented. Patients with
mRCC might not have been observed for a sufficient time
period to see the occurrence of the outcome. Since the data
capture only in-hospital events, morbidity occurring after
discharge could have not been assessed. Therefore, the rate
of complications might have been underestimated owing
to their possible occurrence outside the observational
period. Moreover, a second problem with this scenario is
that the rate of overall and major complications might
have been significantly different among patients under-
going SM for different types of metastases only because of
different lengths of hospital stay. Furthermore, the lack of
a clear operative definition of overall complications could
have led to the inclusion of complications potentially not
related to SM.
Beyond these considerations, a major limitation associat-
ed with the statistical design of the study is the lack of a
multivariate analysis to assess potential associations be-
tween patient-, hospital-, and disease-related characteristics
and the occurrence of in-hospital complications after SM,
which could have led to potentially spurious associations as
those obtained with univariate logistic regression analysis.
Finally, the results presented also have inherent limita-
tions related to the data sources, such as lack of knowledge
on timing of cytoreductive nephrectomy; administration
(and timing) of possible targeted therapy; number, site,
size, and anatomic accessibility of metastases; synchronous
or metachronous interventions; number of metastases
resected at the time of surgery; patient performance status
at surgery and prognostic risk group; intention to treat
(radical vs palliative); type of surgery; and completeness of
SM. These limitations, alongside the aforementioned sources
of bias, inherently prevent any definitive conclusion
regarding the predictors of in-hospital morbidity after SM,
and therefore any guidance for patient counseling. Thus, we
feel that the conclusions of the authors regarding potential
associations between the occurrence of complications and
patient- or hospital-related characteristics might be poten-
tially inconsistent given the strength of evidence provided.
However, Meyer and colleagues should be praised for
their pioneering efforts to fill the gap in knowledge in this
field, providing reliable data on the rate of complications
after SM for RCC, opening new perspectives, and outlining
the current unmet research needs.
Our view is that current knowledge on the perioperative
morbidity of SM is, as for many other topics in renal cancer
research, just the tip of an iceberg that we are now starting
to realize. Although many unmet needs are likely to remain
unsolved owing to the inherent difficulties in conducting
studies of a high level of evidence in the setting of this
complex disease, the urology community should strive to
improve the quality of future trial design with the aim
of providing more granular and clinically meaningful
answers to the current controversies.
Conflicts of interest: The authors have nothing to disclose.
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