Identification of an Effective Two-stage Adaptive Intervention for Reducing Loneliness among Hong Kong Chinese Older Adults

To develop and identify an effective two-stage adaptive intervention for optimizing the reduction of loneliness and four secondary outcomes (stress, sleeping problem, symptoms of depression and anxiety) among Hong Kong Chinese older adults using the sequential multiple assignment randomized trial (SMART) approach. The specific objectives of this proposed study are as follows:

1. To evaluate whether a telephone-delivered behavioral activation (Tele-BA) intervention or a telephone-delivered mindfulness (Tele-MF) intervention is a more effective first-stage intervention in terms of reducing loneliness and four secondary outcomes.
2. To evaluate whether extending the original first-stage intervention with an additional motivation component or switching to an alternative intervention is more effective in reducing loneliness and four secondary outcomes when participants are not responding to the first-stage intervention.
3. To evaluate whether the Tele-BA-Tele-MF sequence (8 weeks) or the Tele-MF-Tele-BA sequence (8 weeks) is more effective in reducing loneliness and four secondary outcomes.
4. To identify which of our four embedded 2-stage adaptive interventions is most effective for reducing loneliness and the four secondary outcomes: (1) 4-week Tele-BA: if no response, deliver another 4 weeks of Tele-BA with an additional motivation component (Tele-BA-and-Tele-BA); otherwise, two monthly booster sessions; (2) 4-week Tele-BA: if no response, deliver a further 4 weeks of Tele-MF (Tele-BA-and-Tele-MF); otherwise, two monthly booster sessions; (3) 4-week Tele-MF: if no response, deliver another 4 weeks of Tele-MF with an additional motivation component (Tele-MF-and-Tele-MF); otherwise, two monthly booster sessions; (4) 4-week Tele-MF: if no response, deliver a further 4 weeks of Tele-BA (Tele-MF-and-Tele-BA); otherwise two monthly booster sessions.