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Table 1 Methodological quality of lung cancer prognosis studies

From: Survival of patients with non-small cell lung cancer without treatment: a systematic review and meta-analysis

Study Design/Domain/Criterion Criteria fulfilled
  n/N %
Cohort studies (11 items)
  Participation bias
A Population of interest is adequately described for key characteristics [15] 7/7 100
B Study setting and geographic location is adequately described [15] 7/7 100
C Baseline sample is adequately described for key characteristics [15] 4/7 57
D Inclusion and exclusion criteria are adequately described [15] 5/7 71
E There is adequate participation in the study by all eligible patients [15] 7/7 100
  Attrition bias
F Follow-up is sufficiently long for outcome to occur (≥6 months) [16, 18, 19, 46] 6/7 86
G Patients with missing data were reported [15, 17] 7/7 100
  Outcome measurement
H Definition of outcome is provided a priori[15] 7/7 100
I Objective definition of outcome is provided [15, 16, 18, 19] 7/7 100
  Data analysis and reporting
J Alpha error and/or beta error is specified a priori 2/7 29
K Frequencies of most important data (for example, outcomes) are presented [18, 19, 47] 7/7 100
Randomized controlled trials (14 items)
  Participation bias
L Population of interest is adequately described for key characteristics [15] 15/15 100
M Study setting and geographic location is adequately described [15] 7/15 47
N Baseline sample is adequately described for key characteristics [15] 14/15 93
O Inclusion and exclusion criteria are adequately described [15] 14/15 93
P Patients were balanced in all aspects except the intervention 15/15 93
  Attrition bias
Q Follow-up is sufficiently long for outcome to occur (≥6 months) [16, 18, 19, 46, 48] 8/15 53
R Proportion of sample completing the study is adequate (≥80%) [15, 16, 18, 47, 49, 50] 9/15 60
S Description of withdrawal (incomplete outcome data) is provided [15, 17] 15/15 100
T Characteristics of drop-outs versus completers is provided [15] 2/15 13
  Outcome measurement
U Definition of outcome is provided a priori[15] 15/15 100
V Objective definition of outcome is provided [15, 16, 18, 19] 15/15 100
  Data analysis and reporting
W Alpha error and/or beta error is specified a priori 7/15 47
X Data analysis was based on intention-to-treat analysis principle [17] 9/15 53
Y Frequencies of most important data (for example, outcomes) are presented [18, 19, 47] 15/15 100