3.3. Subgroup analysis
Subgroup analyses were also conducted based on the type of surgery, FET
graft type, and the geographical location of the study center (Table
2 ). The pooled estimates of outcomes in subgroup analyses revealed that
the heterogeneity for secondary endovascular treatment during follow-up
post-FET period disappeared, as there was no heterogeneity among
patients receiving the Cronus (I2 = 15.1%) or
Frozenix (I2 = 1%) stent-grafts. In addition, amongst
patients undergoing emergent surgery, the source of heterogeneity was
non-significant (I2 = 8%). Based on the geographical
location of study centers, there was least source of heterogeneity among
Asian countries (I2 = 39.5%). On the other hand, with
regards to the development of dSINE, there was no heterogeneity
(I2 = 0%) amongst European studies, including those
utilizing Thoraflex Hybrid and E-Vita stent-grafts. Moreover, the pooled
estimates of postoperative endoleak were also without heterogeneity
(I2 = 0%) in patients receiving Thoraflex Hybrid as
well as those undergoing FET HP implantation in European centers. Other
subgroup analyses and their effect on the pooled estimates of outcomes
and the heterogeneities are summarized in Table 2 .