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Risk-of-bias assessment (a) random number generation; (b) allocation concealment; (c) blinding of patients and clinicians; (d) blinding of assessors and analysts; (e) data completeness; (f) selective reporting; (g) other sources of bias; “++”: low risk; “+”: probably low risk; “−”: probably high risk; (h) overall high risk; (m) overall moderate risk; (l); overall low risk.
