3.1 Characteristics and quality analysis of enrolled studies
Literature search was performed using the priori determined search
strategy. A total of 2658 records were retrieved through searching
databases of PubMed, Web of Science, the Cochrane Library and Scopus.
After exhaustive screening and careful assessment, 46 studies including
4484 patients were ultimately included in the meta-analysis1-9,11,12,17-51. The detailed process and the reason
of excluded studies were demonstrated as flow chart, Fig.1 .
The characteristics of entered studies were expatiated in Table
1 . Among them, two studies {de Vicente, 2019 #4;Foy, 2017 #7}were
splitted as two separate data sets on account of different
antibodies12,39{de Vicente, 2019 #4;!!! INVALID
CITATION !!!, #0;Quan, 2020 #20}. One study was stratified as two
separate data sets for prognosis due to two different tissue sources,
and also, was tread as three separate data sets for clinical parameters
based on three various assay cutoffs9. A study was
converted to two separate data sets as a result of two different assay
cutoffs. There were two separate data sets for clinical parameters and
three separate data sets for prognosis in study reported by
Pena-Cardelles et al.11 Six studies focused on PD-L1
expression in TC and IC that were calculated separately as two
independent datasets1,23,34,35,47,49. 46 enrolled
studies were judged whether to provide clinical variables or prognostic
variables, of which results were marked as āYā or āNā. The
classification and assessment for variables suitable for synthesis were
detailed in Table S1 .
Quality analysis of enrolled studies was performed according to the
evaluation criteria adapted from REMARK guidelines, of which results
were summarized in Supplemental Fig. S1.