The effects of volunteering on loneliness among lonely older adults: the HEAL-HOA dual randomised controlled trial.

Background: Previous randomised controlled trials have largely relied on self-reported volunteer work to assess the effects of volunteering and have rarely provided structured volunteering activities during the intervention period. The present study aimed to investigate the effects of social volunteering work over 12 months on loneliness among older adults during the COVID-19 pandemic.

Methods: A dual randomised controlled trial was done in Hong Kong to investigate the long-term effects of telephone-delivered psychosocial interventions by older Chinese volunteers who were screened as lonely, for older adult recipients who had low income, lived alone, felt lonely, and were digitally excluded. Participants were included if they were aged 50-70 years; had provided consent to be trained and serve as a volunteer for at least 2 h per week for 6 months; had at least 3 years of secondary school education; had no severe self-reported physical, mental, or cognitive health problems; were not working full or part-time; had engaged in formal volunteering fewer than four times within the past year; and were lonely (ie, had a score of at least 6 on the three-item UCLA Loneliness Scale). Participants were allocated into either the volunteering or control group (psychoeducation programme) using a random number method. The details of group allocation were concealed as the research assistant responsible for randomisation was different to the research assistants responsible for recruitment and assessments (who were masked to the condition). Following a 6-week training, the volunteers delivered a psychosocial intervention to older intervention recipients for 6 months. The primary outcome was loneliness measured with the 20-item UCLA Loneliness Scale and the De Jong Gierveld (DJG) Loneliness Scales at 6 months and 12 months. Assessments were performed before training (baseline; T1), at 6 months (T2), and at 12 months after training (T3). The intention-to-treat principle was used to compare the effects of volunteering between the two groups. The trial was registered in the Clinical Trials Registry of the University of Hong Kong Clinical Trials Centre (HKUCTR-2929). This trial has completed.

Findings: Between May 3, 2021, and Oct 6, 2022, a total of 375 individuals were recruited to the trial, including 84 males (22%) and 291 females (78%). 185 were randomly assigned to the volunteering group (56 to deliver a mindfulness intervention, 65 to deliver a behavioural activation intervention, and 64 to deliver a befriending intervention) and 190 were assigned to the control group. 311 (83%) of 375 participants were 60 years or older (median 64 years [SD 4·86]). Participants in the volunteering group reported a significantly lower level of loneliness at T2 (d ranged from -0·41 to -0·70) compared with T1 than participants in the control condition. There was a significant decrease in loneliness measured using the UCLA Loneliness Scale at T2 in the volunteering group but such a decline was not shown in the control group (condition × time interaction, estimate 0·19 [95% CI 0·08 to 0·29], p=0·00058, d=-0·41). Similarly, when measured with the DJG Loneliness Scale, there was a significantly greater decrease in loneliness in the volunteering group compared with the control group at T2, including a medium to large effect size on total DJG scores (estimate 1·34 [95% CI 0·83 to 1·84], p<0·0001, d=-0·70) and a medium effect size on emotional (estimate 0·63 [0·35 to 0·90], p<0·0001, d=-0·59) and social subscales (estimate 0·71 [95% CI 0·37 to 1·05], p<0·0001, d=-0·58). Although most of the positive effects of volunteering were not sustained at T3, the volunteers who continued to volunteer for more than 2 h per week at T3 reported lower levels of loneliness than those who did not maintain volunteering.

Interpretation: This randomised controlled trial demonstrates the beneficial effect of volunteering on reducing loneliness in older adults who feel lonely, and that this benefit can be maintained through continued participation in voluntary work. Future intervention programmes should strengthen older adults' commitment to volunteer.

Funding: Research Grants Committee of the Hong Kong Special Administrative Region, China.