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Forest plot for quality of reduction. Subgroup-RCT: RR (95%CI) = 0.55 (0.33, 0.91), z = 2.34, p = 0.019; subgroup-retrospective: RR (95%CI) = 0.57 (0.32, 0.98), z = 1.99, p = 0.045; overall: RR (95%CI) = 0.56 (0.38, 0.81), z = 3.06, p = 0.002.
