People with severe mental ill health (SMI) experience some of the largest health inequalities of any sector within society. For these inequalities to be reduced, an understanding of the behavioural determinants of health in this population is needed.

Utilising data from the Closing the Gap Health Study, we aimed to assess the extent to which people with SMI report health-risk factors and behaviours, their interest in modifying them, and the factors associated with being motivated to modify these behaviours.

Adult (≥18 years old) participants were recruited via primary and secondary care in the English National Health Service. To be eligible, participants needed to have a documented diagnosis of schizophrenia, psychotic disorders or bipolar disorder. Data were collected by survey on demographics, general physical health, diet, physical activity, alcohol, smoking and body mass index.

Between April 2016 and March 2020, n = 9914 participants were recruited. Among people with SMI, high rates of obesity (37.5%), infrequent physical activity (62.0%), not meeting current guidelines (≥5) for the consumption of fruit and vegetables (85.0%) and smoking (42.2%) were observed. However, most participants were motivated to reduce health-risk behaviours. Perceiving the importance of health-promoting behaviours, being of poorer general health and being female were significantly associated with being motivated to modify health-risk behaviours.

Despite experiencing poor physical and mental health outcomes compared with the general population, and contrary to popular misconceptions, people with SMI perceive health as important and are motivated to make behavioural changes to improve health.

People with severe mental illness (SMI) are more likely to have obesity and engage in health risk behaviours than the general population. The aims of this study are (1) evaluate the effectiveness of interventions that focus on body weight, smoking cessation, improving sleeping patterns, and alcohol and illicit substance abuse; (2) Compare the number of interventions addressing body weight and health risk behaviours in low- and middle-income countries (LMICs) v. those reported in published systematic reviews focusing on high-income countries (HICs).

Intervention studies published up to December 2020 were identified through a structured search in the following database; OVID MEDLINE (1946–December 2020), EMBASE (1974–December 2020), CINAHL (1975–2020), APA PsychoINFO (1806–2020). Two authors independently selected studies, extracted study characteristics and data and assessed the risk of bias. and risk of bias was assessed using the Cochrane risk of bias tool V2. We conducted a narrative synthesis and, in the studies evaluating the effectiveness of interventions to address body weight, we conducted random-effects meta-analysis of mean differences in weight gain. We did a systematic search of systematic reviews looking at cardiometabolic and health risk behaviours in people with SMI. We compared the number of available studies of LMICs with those of HICs.

We assessed 15 657 records, of which 9 met the study inclusion criteria. Six focused on healthy weight management, one on sleeping patterns and two tested a physical activity intervention to improve quality of life. Interventions to reduce weight in people with SMI are effective, with a pooled mean difference of −4.2 kg (95% CI −6.25 to −2.18, 9 studies, 459 participants, I2 = 37.8%). The quality and sample size of the studies was not optimal, most were small studies, with inadequate power to evaluate the primary outcome. Only two were assessed as high quality (i.e. scored ‘low’ in the overall risk of bias assessment). We found 5 reviews assessing the effectiveness of interventions to reduce weight, perform physical activity and address smoking in people with SMI. From the five systematic reviews, we identified 84 unique studies, of which only 6 were performed in LMICs.

Pharmacological and activity-based interventions are effective to maintain and reduce body weight in people with SMI. There was a very limited number of interventions addressing sleep and physical activity and no interventions addressing smoking, alcohol or harmful drug use. There is a need to test the feasibility and cost-effectiveness of context-appropriate interventions to address health risk behaviours that might help reduce the mortality gap in people with SMI in LMICs.