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A funnel plot shows no evidence of publication bias among all the studies (Begg’s Test P=.97). We also did a similar analysis for the four different subsets of studies (case-control, no tobacco affiliation, P = .544 by Begg’s test; case-control, tobacco affiliated, P=.476; cohort, no tobacco affiliation, P=.536; cohort, tobacco affiliation, P=.999), which also failed to find evidence of publication bias.
