Abstract: We included only one study that compared nidotherapy-enhanced standard care with standard care alone (total 52 participants); this study was classified by its authors as a 'pilot study'. The duration of the included study was 18 months in total. The single study examined the short-term (up to six months) and medium-term (between six and 12 months) effects of nidotherapy-enhanced standard care versus standard care. Nidotherapy-enhanced standard care was favoured over standard care for social functioning in both the short term (n = 50, 1 RCT, MD -2.10, 95% CI -4.66 to 0.46) and medium term (n = 37, 1 RCT, MD -1.70, 95% CI -4.60 to 1.20, Very low quality); however, these results did not reach statistical significance. Results concerning engagement with non-inpatient services favoured the intervention group in both the short term (n = 50, 1 RCT, MD 2.00, 95% CI 0.13 to 3.87) and medium term (n = 37, 1 RCT, MD 1.70, 95% CI -0.09 to 3.49), with statistical significance evident in the short term, but not in the medium term. Results of people leaving the study early favoured the intervention in the short term (n = 52, 1 RCT, RR 0.86, 95% CI 0.06 to 12.98), with slight favour of the control group at medium term (n = 50, 1 RCT, RR 0.99, 95% CI 0.39 to 2.54); again, these results did not reach statistical significance. Results for the adverse effects/events of death (measured by 12 months) favoured the intervention (n = 52, 1 RCT, RR 0.29, 95% CI 0.01 to 6.74, Very low quality) but with no statistical significance. Skewed results were available for mental state, service use, and economic outcomes, and present a mixed picture of the benefits of nidotherapy. Further research is needed into the possible benefits or harms of this newly-formulated therapy. Until such research is available, patients, clinicians, managers and policymakers should consider it an experimental approach.

Plain-language summary: This review includes one small pilot study with 52 participants. The study compared nidotherapy with standard care versus standard care alone and lasted 18 months. Findings suggest some limited evidence that those who received nidotherapy might experience a slight improvement in social functioning or personal relationships, mental state and may spend less time as inpatients in hospital over the course of 12 months, but there is no information concerning the appropriateness of this for the individual. However, these limited findings need to be treated with considerable caution. The degree of any possible improvements that come from taking part in nidotherapy remain unclear due to the single study’s small sample size, incomplete evidence and risk of bias. No evidence is available on the effect of nidotherapy on general functioning, quality of life, taking medication, satisfaction with treatment, employment status or adverse effects. Further research is required to fill this gap in knowledge about the effectiveness, benefits and possible hazards of nidotherapy. Until such a time, people with mental health problems, health professionals, managers and policymakers should consider this new therapy an experimental one. This summary has been written by a consumer Ben Gray (Benjamin Gray, Service User and Service User Expert, Rethink Mental Illness. Email: [email protected]).