Randomization
The participants were assigned into CBT-based intervention group, sexual health education receiving group, and control group with a ratio of 1:1:1 by block randomization using Random Allocation Software (RAS) with a block size of 6 and 9. The type of allocation was written on paper and put in sequentially numbered opaque envelopes for the allocation concealment. A non-involved person in the sampling opened the envelopes consecutively. The outcome assessor (the fifth author) was blinded.