Statistical analysis
psychosis, schizophrenia, bipolar disorder
REGRESSION, SECONDARY, RECRUITMENT
The original recruitment target was 336 participants across approximately 56 general practice clusters, to detect a mean between group difference of 0.45 pointsA detailed statistical analysis plan was approved before locking the trial database.The change between baseline and follow-up in the primary outcome of overall MANSA score was analysed with a random effects linear regression model, with cluster-level minimisation factors (region and practice size) and individual-level baseline overall MANSA score included as fixed effects covariates, and general practice as a random effect. Prespecified sensitivity analyses of the primary outcome assessed the robustness of the primary analysis: (a) per-protocol analysis of participants with follow-up data within their prespecified window; (b) per-protocol analysis to assess the impact of availability of care partner to deliver the intervention, excluding practices where a care partner was available <70% of time; (c) using multiple imputation to assess the effect of missing primary outcome data, including the number of care partner interactions as an auxiliary variable; and (d) complier-average causal effect analyses using two prespecified definitions of fidelity (attendance at a minimum of six care partner sessions, either face to face, by telephone or virtually, with each session lasting a minimum of 10 min; and attendance at a minimum of four care partner sessions during which goals were discussed).To explore the effects of the COVID-19 pandemic, participants were categorised according to whether their follow-up data was collected before or during the pandemic, with three additional prespecified sensitivity analyses for both the primary outcome and the secondary outcome TUS: (a) separate models for participants providing follow-up data before and after the start of the first UK lockdown, (b) adding an interaction term of allocated group/COVID-19-affected categorisation to the primary analysis model and (c) adding the COVID-19-affected categorisation covariate as an adjustment to the primary analysis model. We also undertook four planned subgroup analyses (region, practice size (small versus large), diagnostic group (bipolar disorder versus schizophrenia or other psychosis) and usual care provider at screening (primary versus secondary care)) of the primary outcome by including the interaction effect of allocated group and the subgroup in separate regression models. All fully adjusted sensitivity and subgroup analyses included the minimisation factors, general practice as a random effect and controlled for the corresponding baseline score.We analysed continuous secondary outcomes with similar random effects linear regression modelling. Two identified outliers were removed from the analyses of the TUS. We were unable to complete the planned analysis of the number of healthcare monitoring outcomes because of limited availability of data (primary care notes reviews were carried out for 32 participants). After discussion with the oversight committees, no inferential analyses were undertaken of the Brief INSPIRE because of both the levels and patterns of missing data at both baseline and follow-up. No inferential analyses were planned/undertaken of the lifestyle outcomes.