Learning, doing and sticking with it: A qualitative study on achieving clinically significant reduction in cardiovascular disease risk in a healthy lifestyle intervention for people with serious mental illness.

People with serious mental illness (SMI; e.g. schizophrenia) have mortality rates two to three times higher than the general population, largely due to a higher prevalence of cardiovascular disease (CVD). Healthy lifestyle interventions can improve the health of people with SMI, but information about why these interventions work for some and not others is scarce. Our study aims to qualitatively explore differences in these two groups' overall experiences and application of the intervention. Data were drawn from a randomised effectiveness trial of a peer-led healthy lifestyle intervention. Qualitative data from interviews and focus groups with 21 participants were linked to their 12-month outcome data. Grounded theory was used to compare the experiences of participants who achieved clinically significant CVD risk reduction (i.e. clinically significant weight loss or clinically significant improvements in cardiorespiratory fitness) versus those who did not. Three qualitative themes: learning, change, sticking with it - differentiated participants who achieved CVD risk reduction and those that did not. Participants achieving CVD risk reduction described learning and applying specific knowledge and skills related to a healthy lifestyle when making health decisions, made healthy concrete changes to diet and physical activity, and stuck with those changes. Participants not achieving clinically significant CVD risk reduction reported surface-level learning about healthy lifestyle practices, difficulty sticking with healthy changes, and were more likely to report ambiguous or no changes. Our findings suggest that healthy lifestyle interventions for people with SMI should provide experiential in-vivo learning experiences while periodically assessing participants' understanding and then tailoring the intervention to their needs. It is important to build self-efficacy for health behaviour changes by creating early perceptions of success, which was found to enhance motivation and sustain behaviour change. Helping people with SMI develop and strengthen their support systems will also be an important factor for building and sustaining health behaviour changes.