Limitation:
The main limitations of this study are as following. Firstly, all the
included studies are observational design and significant differences in
clinical characteristics between CRT-D and CRT-P were observed. Even
though we extracted adjusted HR to minimize the influence of those
confounders and made results more reliable, the influence of unknown
confounders still cannot be eliminated. Secondly, the majority of
including studies are from European; therefore, the effect of additional
ICD on all-cause mortality may not be generalizable to population from
other areas. Thirdly, sample size varied greatly across the included
studies, which means a different statistical power of included studies.
However, sensitivity analysis of primary outcome suggested a stable
result. Fourthly, limited by high heterogeneity and little data, this
work cannot illustrate the benefits of CRT-D in long-term follow-up.
Meanwhile, the impact of gender on benefits of CRT-D remains unclear.
Finally, patient’s quality of life and re-hospitalization rate after
implantation are vital clinical index to guide the device selection, but
this meta-analysis did not focus on them.
Acknowledgments: Not applicable.
Funding: Not applicable.
Conflicts of interest/Competing interests: Not applicable
Availability of data and material: Not applicable
Code availability: STATA 14 (Stata Corp LP, College Station,
Texas)