The telephone group received telephone calls. All non-response and refusing donors were included for further follow-up. Donors who answered the phone call and agreed to be interviewed were asked the reasons why they had stopped donating according to a pre-designed questionnaire. All of the responsed donors were re-recruited by altruistic appeal.

The SMS intervention group received the following text message:"Dear donors, Thank you for your donation through which your love brought hope to those helpless patients and your donated blood reignited the fire in their lives. If you can, please consider donating blood again to save a life. Thank you again for your support!" . All donors either receiving or not receiving the message were included for further follow-up.

No intervention will be giving to this group.

From 20 October to 10 November 2016, telephone calls were given to the donors in the phone call group

Number of blood donors donate blood again divided by the number of participants in every group after intervened.

The reasons of not donating again in the telephone group.