Table 2. Summary of Risk of Bias Assessment.

Source	Cohort studiesa
	Representativeness of exposed group	Selection of nonexposed group		Ascertainment of exposure	Outcome of interest not present at start of study		Comparability of cohort		Assessment of outcome	Was follow-up long enough for outcomes to occur?		Adequacy of follow-up of cohorts
Meyers et al,21 2021	1	1		1	1		1		1	1		1
Schneeweiss et al,22 2021	1	1		1	1		1		1	1		1
Source	Randomized clinical trialsb
	Bias arising from the randomization process		Bias because of deviations from intended interventions			Bias because of missing outcome data		Bias in measurement of the outcome			Bias in selection of the reported result
Bieber et al,23 2021	Low		Low			Low		Low			Low
Blauvelt et al,24 2021	Low		Low			Low		Low			Low
Blauvelt et al,25 2022	Low		Low			Low		Some concerns			Low
Eichenfield et al,26 2021	Low		Low			Low		Low			Low
Gooderham et al,27 2019	Low		Low			Low		Some concerns			Low
Guttman-Yassky et al,28 2020	Low		Low			Low		Some concerns			Low
Guttman-Yassky et al,29 2021	Low		Low			Low		Low			Low
Katoh et al,30 2022	Low		Low			Low		Some concerns			Low
Reich et al,31 2020	Low		Low			Low		Low			Low
Reich et al,32 2021	Low		Low			Low		Low			Low
Silverberg et al,33 2020	Low		Low			Low		Low			Low
Simpson et al,34 2020 (Simpson 2020a)	Low		Low			Low		Low			Low
Simpson et al,35 2020 (Simpson 2020b)	Low		Low			Low		Low			Low
Simpson et al,36 2021	Low		Low			Low		Low			Low
Zhao et al,37 2021	Low		Low			Low		Some concerns			Low

^a Risk of bias assessed by the Newcastle-Ottawa Scale. In each domain, 1 corresponds to low risk of bias and 0 corresponds to high risk of bias. Studies with a total score (namely the sum score of all domains) of 7 or more points were considered high-quality studies.

^b Risk of bias assessed by the Cochrane Risk of Bias Tool (RoB, version 2.0).