Table 3. Assessment of risk of bias in clinical trials using the RoB 1.0 tool and evaluation of quality of cohort and control case studies using the Newcastle-Ottawa scale.

	Study	Risk of bias
		Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessors	Incomplete outcome data	Selective outcome reporting	Other sources of bias
Clinical trials (n = 39)	Yamamoto et al., 199586	Unclear	High	High	High	Low	Low	Low
	Bate et al., 199550	Unclear	Unclear	Low	Low	Low	Low	Low
	Goh et al., 199587	Unclear	Unclear	Unclear	Low	Unclear	Low	Low
	Marzio et al., 199551	Unclear	Unclear	Low	Low	Low	Low	Low
	Leite et al., 199658	Unclear	Unclear	Unclear	Unclear	Low	Low	Low
	Valenzuela et al., 199652	Unclear	Unclear	Low	Low	Low	Low	Low
	Muckadell et al., 199739	Low	Low	Low	Low	Low	Low	Low
	Labenz et al., 199753	Low	Unclear	Low	Low	Low	Low	Low
	Annibale et al., 199755	Unclear	Unclear	Low	Low	Low	Low	Low
	Hasselgren et al., 199754	Unclear	Low	Low	Low	Low	Low	Low
	Lind et al., 199961	Unclear	High	Low	Low	Low	Low	Low
	Soga et al., 199937	Low	Low	Unclear	Unclear	Low	Low	Low
	Klinkenberg-Knol et al., 200060	High	Unclear	Unclear	Low	High	Low	Low
	Ladas et al., 200057	Low	High	Low	High	Low	Low	Low
	Richter et al., 200059	Unclear	Unclear	Low	Unclear	Low	Low	Low
	Blum et al., 200062	Unclear	Low	Low	Low	Low	Low	Low
	Noordzij et al., 201188	Unclear	Low	Low	Low	Low	Low	Low
	Gottrand et al., 200133	Low	Low	Low	Low	Low	Low	Low
	Esaki et al., 200265	Unclear	Unclear	Low	Low	Low	Low	Low
	Rabeneck et al., 200264	Low	Low	Low	Low	Low	Low	Low
	Zhou et al., 200243	Unclear	Unclear	High	High	Low	Low	Low
	Thjodleifsson et al., 200063	Low	Low	Low	Low	Low	Low	Low
	Armstrong et al., 200566	Low	Low	Low	Low	Low	Low	Low
	Fujiwara et al., 200589	Unclear	Unclear	High	High	Low	Low	Low
	Manes et al., 200538	Low	Unclear	Low	High	Low	Low	Low
	Ohkusa et al., 200567	High	High	Unclear	Unclear	Low	Low	Unclear
	Van Zanten et al., 200535	Low	Low	Low	Low	Low	Low	Low
	Madisch et al., 200568	Low	Low	Low	Low	Low	Low	Low
	Schooler et al., 200832	Low	Unclear	Low	High	Low	Low	Low
	Howden et al., 200969	Unclear	Unclear	Unclear	High	Low	Low	Low
	Lundell et al., 200970	Unclear	Unclear	Low	Unclear	Low	Low	Low
	Miner et al., 201091	Low	Low	Low	Low	Low	Low	Low
	Hudzik et al., 201072	High	High	Low	High	Low	Low	Low
	Ferreiro et al., 201071	Unclear	Unclear	Low	Low	Low	Low	Low
	Miwa et al., 201173	Low	Low	Low	Low	Low	Low	Low
	Sakurada et al., 201292	Unclear	Low	Low	High	Low	Low	Low
	Ummarino et al., 201136	Unclear	Unclear	Unclear	Unclear	Low	Low	Low
	Liu et al., 201390	Low	Unclear	Low	High	Low	Low	Low
	Solana et al., 201393	Low	Unclear	Unclear	Unclear	Low	Low	Low
	Evaluation of quality of cohort and control case studies using the Newcastle-Ottawa scale
	Study		Domains
			Selection (4*)		Comparability (2*)		Outcome (3*)
Cohort studies (22)	Klinkenberg-Knol et al., 199474	4*			1*		3*
	Kreutz et al., 201075	4*			2*		3*
	Van Boxel et al., 201076	4*			2*		3*
	Zairis et al., 201094	4*			2*		3*
	Cadle et al., 200713	4*			2*		3*
	Study		Domains
			Selection (4*)		Comparability (2*)		Outcome (3*)
Cohort studies (22)	Teichert et al., 201177	4*			2*		3*
	Ligumsky et al., 201180	3*			2*		3*
	Galante et al., 201296	4*			1*		3*
	Lin et al., 201281	4*			2*		3*
	David-Neto et al., 201249	4*			1*		3*
	Soriano et al., 201416	4*			2*		3*
	Chen et al., 201428	4*			2*		3*
	Wang et al., 201797	4*			2*		3*
	Gomm et al., 201644	4*			2*		3*
	Yi et al., 201747	4*			2*		3*
	Varallo et al., 201841	4*			2*		3*
	Imperatore et al., 201845	4*			2*		3*
	Lazzerini et al., 201842	4*			1*		3*
	Li et al., 201848	4*			2*		3*
	Study		Domains
			Selection (4)		Comparability (2*)		Exposure (3*)
Case-control study (2)	Chularojanamontri et al., 201285	4*			2*		3*
	Heijgen et al., 201646	4*			2*		3*