2.5 Bias assessment
The risk of bias was assessed using the approach recommended by the
Cochrane Handbook for Systematic Reviews of Interventions[17]. The
following characteristics for each article were assessed: (1) allocation
concealment; (2) random sequence generation; (3) blinding of outcome
assessment; (4) blinding of personnel and participants; (5) selective
reporting; (6) incomplete outcome data; and (7) other bias.