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Quality of the included studies
Abbreviations: Randomization: A, appropriate; B, unclear; C, quasi-randomization; D, inappropriate. Blinding: A, double blind; B, blinding of participants or investigators; C, blinding of analyst only; D, unclear; E, not blinded. Allocation concealment: A, concealed; B, unclear; C, not concealed. Crossover study: N, not; Y, yes. Intention-to-treat analysis: A, appropriate; B, unclear.
