KindnessbyPost: An Economic and Clinical Evaluation of a Participatory Public Mental Health Intervention

Abstract Background #KindnessbyPost (KbP) is a “national kindness exchange”. Participants send and receive a card by post to different, unknown people containing messages of good will. Previous evidence suggests participation in KbP may improve loneliness and wellbeing. We evaluated the outcomes and associated costs of KbP and explored the feasibility of collecting health economic measures for future research. Methods We used a pre-post, observational study design. Participants in two KbP exchanges in 2021 were invited to complete an online questionnaire. It included self-reported measures of psychological wellbeing and loneliness, capability, and healthcare service use. Data were collected at three time-points: exchange start (baseline), exchange-end (2 weeks), and 3-months post-exchange. Additional cost data were obtained from the KbP programme organisers. Results Across exchanges, baseline data were obtained for 1,285 participants (from 1,142 individuals). In total, 623 (48%) of participants were followed up at exchange-end, and 414 (32%) at 3-months. 70% of participants were aged between 31 and 60 (n = 789). 94% of participants were female (1,075) and 95% of white ethnicity (1,078). Compared to baseline, loneliness and wellbeing improved at exchange end (‑0.21, 95% CI: -0.29 to -0.12; 0.68, 0.47 to 0.88 respectively) and at 3 months follow up (-0.40, -0.50 to -0.30; 1.01, 0.77 to 1.25 respectively). We observed no difference from baseline in capability at both follow up points (mean (SD) at baseline: 0.52(0.22); exchange-end: 0.53(0.22); 3-months: 0.53(0.22)). The average cost of delivering the intervention was £0.67–0.87 per participant. Conclusions We observed a small, sustained improvement to people’s wellbeing and loneliness following participation in a KbP exchange. Given the study design, causal attribution to KbP is uncertain. However, our results are consistent with previous evaluations and offer preliminary evidence that KbP may be an effective mental wellbeing intervention. Given its cheap cost (estimated at £0.67-£0.87 per participant) and highly scalable design, KbP could be an effective and cost-effective intervention for improving public mental health, which warrants definitive evaluation of effectiveness and cost-effectiveness in future. Our study also demonstrates the feasibility of collecting the wellbeing and health economic outcome measures needed for this research.