Chapter 7 172 Methods Study setting and data collection This analysis involved patients with SMI from two mental health care institutions in the greater Rotterdam area, the Netherlands. Participants were from 14 participating community mental health teams from these institutions. These teams provided rehabilitation-oriented clinical case management. This analysis did not require extra assessments of patients as the data from our RCT on IMR (11, 21) were used. Inclusion criteria for this RCT were as follows: age 18–65 years; diagnosis with an SMI such as schizophrenia or a persistent mood disorder with or without comorbid disorders (i.e., substance abuse and personality disorders); receiving outpatient treatment; and being willing and able to give written informed consent. Exclusion criteria comprised previous participation in IMR training and insufficient Dutch language skills. From Oct. 25, 2012 to May 2, 2014, 187 participants for this RCT were recruited through clinician referrals for IMR. We calculated that this study size was appropriate for this RCT (11). These selected clients indicated both a willingness to participate in IMR and to be informed about the study. An assistant researcher explained the study objectives and procedures. If participants agreed to participate in the study, written informed consent was obtained. In this RCT randomly (3:2 ratio) 116 participants were assigned to receive IMR + Care as Usual (n = 116) or Care as Usual alone (n = 71) (11). From Oct 5, 2012 to Feb 1, 2017, per study participant assessments were performed at baseline (T1), after 12 months (post-treatment, T2), and after 18 months (six months of follow-up, T3). As the assessors were blinded to group assignment, the data collection procedure was single-blinded (11). Only the first author had access to information that could identify individual participants during data collection. After data collection, an anonymized data set was used. For the current mediation analysis, the data on self-rated illness self-management, clinical, functional, and personal recovery were used of 165 (88%) participants in this RCT on IMR of whom both assessments at baseline (T1) and at follow-up (T3) were available, irrespective of treatment condition. The scores on those four domains reflected the status of those participants at those time points. With respect to the underlying research question, this sample size allows us to detect medium sized mediation effects with 80% power (27) . Of the 165 participants in this mediation analysis, 104 (63%) in the original RCT belonged to the experimental condition (exposed to care as usual + IMR), and 61 (37%) belonged to the control group (exposed to care as usual, but unexposed to IMR).
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