Clinical benefit of COX-2 inhibitors in the adjuvant chemotherapy of advanced non-small cell lung cancer: A systematic review and meta-analysis

Table 2 The risk of bias in the included studies

Trial or Ref.	Year	Randomization methods	Stratification factors	Double blind	Follow-up	Intent to treat
Lilenbaum et al[26]	2006	Centralized	ECOG PS, age, sex, disease stage, response to treatment	No	NA	Yes
GECO[23]	2007	Centralized	Treatment, gender, PS, disease stage, tumor histology, center (three categories according to size)	No	Median follow-up of 22 mo of alive patients (range 0-40)	Yes
Zhou et al[29]	2007	Envelopes	Types	No	NA	No: 4 of 65 excluded from analysis
Xiong et al[28]	2008	Random number table	Disease stage, COX-2 expression	No	NA	Yes
CYCLUS[24]	2011	Minimization	ECOG PS, sex, stage, smoking status	Yes	After randomization, the follow-up time ranged from 0 to 36 mo	Yes
NVALT-4[25]	2011	Centralized	PS, extent of disease, use of salicylic acid, histology, COX-2 expression, treatment	No	NA	Yes
Liu et al[30]	2012	Mechanical sampling method	Stage	No	NA	Yes
Sörenson et al[32]	2013	Minimization	ECOG PS, sex, stage, smoking status	Yes	After randomization, the follow-up time ranged from 0 to 36 mo	Yes
Gitlitz et al[33]	2014	NA	ECOG PS, sex, age	Yes	The median follow-up time was 30 mo	Yes
0822-GCC[26]	2015	Centralized	ECOG PS, sex, stage, race	Yes	NA	Yes
Teng et al[31]	2015	NA	Serum DKK-1 levels	No	NA	Yes
CALGB-30801[27]	2017	Stratified random permuted-blocks procedure	Sex, histology and chemotherapy, smoking status, stage, age group, PS	Yes	The median follow-up time was 31 mo	Yes

ECOG: Eastern Cooperative Oncology Group; PS: Performance status; COX-2: Cydooxygenase-2; NA: Not available.