Table 1.

Risk of bias in included studies

Study	Random sequence generation	Allocation concealment	Blind participants and personnel	Blind outcome assessment	Incomplete outcome data	Selective reporting
Burke et al18	Unclear	Unclear	Low	Unclear	Low	High
Feighner and Overo19	Unclear	Unclear	Low	Unclear	Low	High
Frank et al20	Unclear	Unclear	Low	Unclear	Low	High
Gastpar et al21	Low	Unclear	Low	Unclear	Low	High
Lepola et al22	Unclear	Unclear	Low	Unclear	Low	High
Mendels et al23	Unclear	Unclear	Unclear	Unclear	Low	High
Montgomery et al24	Unclear	Unclear	Low	Unclear	High	High
Stahl25	Unclear	Unclear	Low	Unclear	Low	High