Correlation between breast cancer and lifestyle within the Gulf Cooperation Council countries: A systematic review

Table 10 Quality of evidence using the GRADE criteria for 3 domains; risk of bias, indirectness and imprecision

GRADE criteria
Ref.	Study design	Risk of bias, No, serious (-1), very serious (-2)	Indirectness, No, serious (-1), very serious (-2)	Imprecision, No, serious (-1), very serious (-2)	Quality of evidence, RCT (starts at high quality), Non-RCT (starts at low)
Al Saeed et al[42], 2015	Retrospective data analysis	No	-1	-1	Very Low
Al-Amri et al[40], 2015	Case-control study	-1	No	-1	Very low
Al-Eisa and Al-Sobayel[36], 2012	Cross-sectional	-2	-1	-2	Very low
Al-Habsi et al[32], 2015	Cross-sectional	-1	-1	-1	Very low
Al-Malki et al[38], 2003	Cross-sectional	No	-1	No	Very low
Al-Shammari et al[33], 2015	Cross-sectional	-1	-2	-1	Very low
Alabdulkarim et al[81], 2018	Single-institute retrospective	No	No	-1	Very low
Albawardi et al[27], 2017	Cross-sectional	-1	-1	No	Very low
AlFaris et al[41], 2018	Case-control and cross-sectional design	-1	-1	No	Very low
Alothaimeen et al[61], 2004	Case-control	-2	No	-1	Very low
Alsaeed et al[43], 2017	Retrospective cross-sectional	No	-1	-1	Very low
Bener et al[45], 2017	Cross-sectional	-1	No	No	Very low
Carter et al[34], 2004	Cross-sectional	-1	-1	No	Very low
Elkum et al[39], 2014	Case-control	No	No	No	Low
Khalid[37], 2007	Cross-sectional	-1	No	No	Very low
Rudat et al[44], 2012	Retrospective epidemiological	No	No	-1	Very low
Sayegh et al[35], 2016	Retrospective data analysis	-1	-1	No	Very low

Taken from GRADE handbook, available at https://gdt.gradepro.org/app/handbook/handbook.html.