Table III.

Assessment of non-randomized study quality

Studies	Quality indicators from Newcastle-Ottawa Scale								Score
	Selection				Comparability	Outcome
	Representativeness of the exposed cohort	Selection of the non-exposed cohort	Ascertainment of exposure	Demonstration the outcome of interest was not present at start of study	Comparability of cohorts on the basis of the design or analysis	Assessment of outcome	Whether follow-up was long enough for outcomes to occur	Adequacy of followup of cohorts
Deng [13]	1	1	1	1	1	1	1	1	8
Hu [14]	1	1	1	1	1	1	1	1	8
Hwang [15]	1	1	1	1	1	1	1	1	8
Liu [16]	1	1	1	1	1	1	1	1	8
Rostambeigi [18]	1	1	1	1	1	1	1	1	8
Wu [19]	1	1	1	1	1	1	1	1	8
Yang [20]	1	1	1	1	1	1	1	1	8