Table S1.

Nine-point NOS scores for the NRCTs

Study	Selection (maximum of four stars)				Comparability (maximum of two stars)	Outcome (maximum of three stars)
	Representativeness of the exposed cohort	Selection of the nonexposed cohort	Ascertainment of exposure	Demonstration of the outcome of interest was not present at the start of the study	Comparability of cohorts on the basis of the design or analysis	Assessment of the outcome	Was follow-up long enough for the outcome to occur	Adequacy of follow-up of cohorts
Sleijfer et al1			*	*		*	*	*
Yoo et al2			*	*		*	*	*
Maki et al3			*	*		*	*	*
von Mehren et al4			*	*		*	*	*
Ray-Coquard et al5			*	*		*	*	*
Santoro et al6			*	*		*	*	*
Bramswig et al7			*	*		*	*	*
George et al8			*	*		*	*	*
Li et al9			*	*		*	*	*

Notes: The NOS score is an easy, convenient tool for quality assessment of nonrandomized studies.

^*Based on three domains: selection of study groups; comparability of groups; ascertainment of exposure/outcome. No major flaws of the included RCTs were detected in assessing their risk of bias.

Abbreviations: NOS, Newcastle–Ottawa Scale; NRCTs, nonrandomized controlled trials.