Randomisation and masking
We coded and grouped the eligible participant prior to randomisation. A research assistant not involved in the study generated the randomisation sequence with an online randomization program, after which block randomization (block size = 4) was adopted to ensure each group contained an equal number of participants, preventing the participants or the researchers from identifying the order of group allocation (ratio = 1:1). The research assistant placed a labelled card indicating the random group allocation (1 – experimental group, 2 – control group) into sequentially numbered sealed opaque envelopes. We adopted a a double-blinded design, informing the participants that two interventions would be implemented but that they would not know to which one they were assigned. We did not disclose the allocation process and other relevant information to the research personnel. To maintain blinding of measurement, outcome evaluators could not discuss the content or participant allocation with any relevant personnel and were only responsible for data collection and analysis of the results.