Table 3

Risk of bias assessment of included trials

Trial ID	Was randomisation carried out appropriately?	Was concealment of treatment allocation adequate?	Were the groups similar at the outset of the study in terms of prognostic factors?	Were the care providers, participants and outcome assessors blind to treatment allocation?	Were there any unexpected imbalances in drop-outs between groups?	Is there any evidence to suggest that the authors measured more outcomes than they reported?	Did the analysis include an intention-to-treat analysis? If so, was this appropriate and were appropriate methods used to account for missing data?	Other sources of bias
Bailey et al 35	Yes	Yes	Yes	Yes	No	No	Yes	Yes
Bolinder et al 32	Yes	Yes	Yes	Yes	No	No	Yes	Yes
CANTATA-D36	Yes	Yes	Yes	Yes	No	No	Yes	Yes
CANTATA-D237	Yes	Yes	Yes	Yes	No	No	Yes	Yes
CANTATA-MP38	Yes	Yes	Yes	Yes	No	No	Yes	Yes
CANTATA-MSU39	Yes	Yes	Yes	Yes	No	No	Yes	Yes
CANTATA-SU40	Yes	Yes	Yes	Yes	No	No	Yes	Yes
DeFronzo et al 41	Yes	Not clear	Yes	Yes	No	No	Yes	Yes
DURATION-842	Yes	Yes	Yes	Yes	No	No	Yes	Yes
EMPA-REG MET20	Yes	Yes	Yes	Yes	No	No	No	Yes
EMPA-REG EXTEND MET29	Yes	Yes	Yes	Yes	No	Yes	No	Yes
EMPA-REG METSU19	Yes	Not clear	Yes	Yes	No	No	Yes	Yes
EMPA-REG EXTEND METSU29	Yes	Not clear	Yes	Yes	No	No	Yes	Yes
EMPA-REG PIO21	Yes	Yes	Yes	Yes	No	Yes	No	Yes
EMPA-REG EXTEND PIO61	Yes	Yes	Yes	Yes	No	Yes	No	Yes
Mathieu et al 43	Yes	Yes	Yes	Yes	No	Yes	No	Yes
MB10203064	Not clear	Not clear	Yes	Yes	No	No	Not clear	Yes
Robdard et al 65	Yes	Yes	Yes	Yes	Yes	No	No	Yes
Strojek et al 45	Yes	Yes	Yes	Yes	No	No	No	Yes
Study 0566	Yes	Yes	Yes	Yes	Not clear	No	Yes	Yes
SUSTAIN 267	Yes	Yes	Yes	Yes	No	No	No	Yes
SUSTAIN 362	Yes	No	Yes	No	No	No	No	Yes
SUSTAIN 434	Yes	No	Yes	No	No	No	No	Yes
SUSTAIN 767	Yes	No	Yes	No	No	No	No	Yes

The high degree of ‘Yes’ status for the Other sources of bias are due to industry sponsoring. In modern pharmacological research, randomised controlled trials are typically industry sponsored. Nonetheless, there have been studies in the past that have indicated a tendency for higher effect sizes to be reported in such trials. As such, these have been identified as unclear with respect to risk of bias.