Table 3.

Risk-of-bias assessments for included non-randomized studies

Study	Risk of bias (domains)
	Inadequate selection of participants	Inadequate consideration of confounding variables	Inadequate measurement of exposure	Inadequate blinding of outcome assessments	Inadequate handling of incomplete outcome data	Selective reporting of outcomes
Podymova et al[34], 19981	Unclear	Unclear	High	Unclear	Unclear	Low
Fiorelli[32], 1999	High	High	Low	Unclear	Low	Low
Virukalpattigo-palratnam et al[36], 2013	Unclear	Unclear	High	Unclear	High	Low
Perlamutrov et al[31], 2014	Unclear	Unclear	High	Unclear	Low	Low
Larionova et al[30], 20151	Unclear	Unclear	High	Unclear	High	Low
Ivashkin et al[35], 2018	Unclear	Unclear	High	Unclear	Low	Low

¹Published studies translated to English from original language. Risk of bias within each domain was judged as low, unclear, or high, using the risk-of-bias assessment tool for non-randomized studies[29].