The COSI study: a multi-site RCT to explore the clinical and cost effectiveness of the Circle of Security Intervention for mothers in perinatal mental health services

Research question: Is the Circle of Security-Parenting (COS-P) intervention more effective than treatment as usual in improving symptoms of maternal mental illness and mother-infant bonding for mothers in NHS perinatal mental health services?

Background: Perinatal mental health services (PMHS) provide multi-disciplinary support for women with mental illness in pregnancy and the first postnatal year. However there are still large gaps in provision, particularly in (a) group therapy approaches; and (b) parent-infant bonding therapies. One intervention showing preliminary efficacious findings and user acceptability is COS-P.

COS-P consists of a brief, 8-session group programme delivered over 10 weeks. The intervention is designed to help parents understand more about their babies, as well as manage their own difficult emotions and how they may affect their relationship with them. A number of previous research studies have explored the effectiveness of COS-P and found that in addition to mothers finding the group approach helpful, improvements were also made in their mental health and relationship with their children.

However, these research studies have been poor quality and there has never been a research trial in England or in a PMHS.

Aims and objectives: The aim of the research is to conduct a Randomised Control Trial (RCT) to test whether COS-P will reduce maternal mental health symptoms in mothers accessing NHS community PMHS compared to treatment as usual (TAU). Secondary objectives include exploring whether the intervention improves maternal sensitivity, emotion regulation skills, attachment security and has an impact on infant development.

Additionally, the project aims to examine whether the intervention is acceptable to participants and NHS staff, and whether it is cost-effective or not.

Methods: An internal pilot study will first be carried out to ensure that a main trial is feasible. A multi-centre RCT will then be carried out in nine NHS PMHS in England with a sample size of 369 participants. Participants will be randomised to the intervention-COS-P plus TAU or to the control group, which will consist of TAU.

Maternal psychopathology as measured by the CORE-OM (primary outcome) will be measured at the beginning of the trial (baseline), 3-months (after the intervention group has finished) and at 7- and 12-months after baseline. A suite of secondary outcomes will also be collected. Service use and quality of life measures will also be collected alongside a process evaluation of women’s and therapists’/practitioners’ views and experiences.

Timelines for delivery: The trial set up phase will last approximately six months. Recruitment will follow until month 30, data collection will continue until month 42, with the last 6 months involving data analysis, write-up and dissemination work.

Anticipated impact and dissemination: This will be the first large study to test whether COS-P is effective for women using PMHS in improving symptoms of their mental illness and the quality of their bond with their babies. It addresses an area of key concern to women, families and the NHS and is an opportunity to reduce the burden of the long-term intergenerational effects of mental illness.

If shown to be effective the intervention could be delivered widely across the NHS. The research team has a strong track record of dissemination; results will be shared widely with families, organisations and professionals in the field.