Study Design and Participants
This RCT included an intervention group and a waitlist control group. The study was conducted in 2 different community settings in Denmark, specifically Copenhagen and a more rural area in Jutland. Ethical approval was obtained at the Central Denmark Region Committee of Health Research Ethics (De Videnskabsetiske Komitéer for Region Midtjylland). All participants provided written informed consent. This study followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline for clinical trials. The detailed trial protocol is available in Supplement 1
Participants were all adults from Denmark. Participants were recruited through primary care physicians and social media and through national associations for caregivers, ads in local newspapers, and local 1-hour informational meetings on the topic of compassion. A total of 192 informal caregivers were assessed for eligibility through a telephone interview. Inclusion criteria included caregivers who were the parent, spouse, adult child, or sibling of a person with mental illness (all mental illnesses were included as described in Diagnostic and Statistical Manual of Mental Disorders [Fifth Edition] [DSM-5]20
), aged 18 to 75 years, and Danish-speaking. The exclusion criteria included diagnosed and untreated mental illness, addiction, meditation practice, or current psychotherapeutic treatment. Of 192 assessed caregivers, 6 (3%) did not meet inclusion criteria, as they were either older than 75 years, they had an established meditation practice lasting more than 1 year, or they were receiving psychotherapy and did not feel they could manage without the help of a therapist.
Participants signed a written informed consent form before answering the demographic and baseline questionnaire and before randomization.
Randomization and Masking
Participants were randomized to CCT or a waitlist control (Figure
) using a computer algorithm with predefined, concealed random numbers. The person creating the computer algorithm with predefined, concealed numbers was a university employee who administers the data software program, Redcap (Vanderbilt University), and was therefore blinded to study participants. We conducted block randomization with 40 participants in each block. The 40 participants in each block were all randomized at the same time, with 20 entering into the intervention group and 20 into the waitlist control group.
Participants enrolled in the trial received an email with a link to the questionnaires that they filled out online from their homes at postintervention and at the 3- and 6-month follow-ups. The data were collected in the RedCap secure university approved system. Once 6-month follow-up data were collected from the intervention and waitlist control groups, the waitlist control group received the CCT intervention.
Owing to the nature of the intervention, participants and the CCT instructor were aware of group allocation for the duration of the study. Data collection was remote, as participants answered the self-report questionnaires from their own homes via a link sent to them by email, and automatic, using the web-based Redcap software to ensure masking of outcome assessors. Everyone involved with the trial, except for the principle investigator and a research assistant, had no access to the data prior to analyzing the data.
The CCT program is a structured and manualized compassion training program that was developed at Stanford University Medical School in 2009.14
The program has a dual focus on training compassion and loving kindness for one’s own suffering and the suffering of others. The focus within CCT is to notice and pay attention to the suffering within oneself or others thereby becoming motivated to relieve that suffering. The program trains a variety of skills and techniques for emotional and mental well-being and is designed to promote qualities of compassion and empathy, and to cultivate kindness toward self, strangers, difficult people, and all sentient beings.19
The CCT program is a 8-week course (eTable 1 in Supplement 2
). Participants meet for 2 hours each week, and the course incorporates practices of compassion, mindfulness, and meditation with scientific research on compassion and related topics in the fields of psychology and neuroscience along with contemplative thinking. Each week, participants engage in class discussions, formal meditations, and dyadic exercises. Participants are asked to meditate daily at home for 20 to 25 minutes using guided compassion meditations accessed through a website and engage in informal compassion practices, sent to the participants in an email each week. The CCT instructor adhered strictly to the CCT manual and received supervision on the teaching throughout the study by mindfulness and compassion practitioners with more than 20 years of experience.
The primary outcome measure used was the 42-item Depression Anxiety Stress Scale (DASS).21
The DASS is scored by summing up the 14 items relevant for each subscale. Lower scores on each scale indicated less psychological distress.
There were 7 overall secondary outcome measures. We included the 10-item Perceived Stress Scale to measure how stressful a person perceives an event or situation in their life to be.22
Scores range from 0 to 40, with higher scores indicating higher perceived stress. The Brief Resilience Scale was used to assess the ability to bounce back or recover from stress (range, 6-10, with higher scores indicating more resilience).23
The World Health Organization 5-item Well-Being Index,24
measured the participant’s current mental well-being; scores range from 0 to 100, and higher scores indicate higher levels of well-being. A score of 50 or lower indicates a risk of developing stress or depression.25
The Emotion Regulation Questionnaire measured respondents’ tendency to regulate their emotions in 2 ways: either cognitive reappraisal or expressive suppression.26
The 12-item Self-Compassion Scale-Short Form was used to measure participants’ level of self-compassion.27
The Multidimensional Compassion Scale was used to measure 4 dimensions of compassion (ie, cognitive, affective, intentional, and motivational) and a total score (H. Jazaieri, P. R. Goldin, E. Simon-Thomas, D. Keltner, and R. Mendoza-Denton, unpublished data, May 2018). The 15-item Five Facet Mindfulness Scale measured 5 dimensions of mindfulness (ie, observing, describing, acting with awareness, nonjudging of inner experience, and nonreactivity to inner experience) and a total score.28,29
Higher scores indicate higher levels of mindfulness. All measures were Danish versions of the instruments, and the Brief Resilience Scale and Multidimensional Compassion Scale were translated into Danish using the World Health Organization guidelines for translating measurements.30
The CCT instructor assessed for safety and adverse events by informing participants that if any trauma resurfaced or other difficult emotions occurred during a session or at home when meditating, the participant should contact the CCT instructor (who is also a licensed psychologist). The participant and instructor would determine together the safest course of action.
The sample size was calculated using effect sizes from related publications,11,15-19
(respective η2 values, and Cohen d) with G*Power statistical software version 3.1 (Heinrich-Heine-Universität Düsseldorf). The power analysis gave an approximate value of a minimum of 77 participants in both groups when we expected a medium effect size of d = 0.5 (α = .05; power, 80%). A minimum of 77 participants per group allowed for an attrition rate of 20%, which gave us a minimum sample size of 64 participants each in the intervention and waiting list control groups.
Data were analyzed by a repeated measurement model with the systematic effect: age, sex, socioeconomic status, years as informal caretaker, schizophrenia (diagnosis of loved one), anxiety (diagnosis of loved one), time (4 time points), intervention, and interaction between time and intervention. We adjusted for schizophrenia, and anxiety as these 2 types of mental illness were overrepresented in the intervention or control group. The repeated measurement model is relatively robust to data missing at random, but we supplemented all analyses with sensitivity analyses representing 4 scenarios with data not missing at random. Missing outcomes were substituted with the model-based estimate, adding or subtracting 0.2 SD in the intervention or control group. We performed a loss to 6-month follow-up analysis for age, sex, educational level, income level, years of caretaking and baseline scores of DASS, Perceived Stress Scale, World Health Organization 5-item Well-Being Index, Brief Resilience Scale, and Emotion Regulation Questionnaire by t tests and χ2 tests (eTables 2-4 in Supplement 2
). P values were 2-sided, and statistical significance was set at P = .05. Data were analyzed from June 4 to July 7, 2020. Full details of the statistical analysis plan are in Supplement 1