Background
The coexistence of mental and physical long-term conditions is highly prevalent, posing significant challenges for individuals, carers and healthcare systems. It leads to poorer health outcomes, increased mortality and economic burden. Despite growing recognition of the need for integrated care for mental and physical health, evidence for interventions remains limited, particularly in low- and middle-income countries. The National Institute for Health and Care Research Improving Outcomes in Mental and Physical Multimorbidity and Developing Research Capacity in South Asia Group focused on three distinct populations: (1) people with severe mental illness and physical health problems; (2) people with common mental disorders and non-communicable diseases and (3) people with common mental disorders and chronic communicable diseases, in Bangladesh, India and Pakistan.

Methods
The programme included epidemiological studies, systematic reviews, surveys and feasibility trials. Evidence reviews were conducted to estimate the prevalence of multimorbidity and identify effective interventions. Interventions were tailored to the local low- and middle-income countries’ context using intervention adaptation frameworks and co-design processes and were tested in feasibility trials. Capacity-building for healthcare professionals and community engagement were integral to the programme, alongside the development of policy and research collaborations.

Results
Key findings included:

Epidemiology: High prevalence of depression (41%) and anxiety (29%) in non-communicable diseases populations; obesity (26%) and combined overweight/obesity (60%) in severe mental illness populations. In non-communicable diseases’ clinics, 35% of patients had scores indicating depression, the majority at moderate or greater severity. Screening for depression in tuberculosis clinics identified possible depression in 35% of patients.

Healthcare gaps: Undiagnosed and untreated physical health conditions were prevalent in severe mental illness populations. For example, 70.8% of people with diabetes, hypertension or hypercholesterolaemia were undiagnosed, and over 50% of those diagnosed were not receiving treatment. Tobacco use was common, with 46.8% of men and 15.0% of women consuming tobacco, yet only 29.1% had attempted to quit in the past year, and two-thirds had not received formal cessation advice.

Interventions
Smoking cessation interventions tailored for severe mental illness populations demonstrated high acceptability and engagement. A culturally adapted behavioural activation intervention for depression in non-communicable diseases’ clinics and integrated depression care in tuberculosis services may improve health outcomes and adherence.

Limitations
COVID-19 pandemic restrictions forced changes to methods or delays affecting several studies. We conducted formative research and feasibility studies rather than definitive studies, limiting conclusions about effectiveness of interventions.

Conclusions
The research highlighted critical gaps in the detection, treatment and integration of care for mental and physical multimorbidity in South Asia. Interventions such as behavioural activation and tobacco cessation counselling showed promise in low-resource settings. Barriers included stigma, fragmented healthcare systems and logistical challenges, requiring systemic solutions. Efforts to engage policy-makers and build capacity were instrumental in advancing integrated care strategies.

The National Institute for Health and Care Research Improving Outcomes in Mental and Physical Multimorbidity and Developing Research Capacity programme advanced the understanding of multimorbidity in South Asia and demonstrated the feasibility of tailored, scalable interventions and capacity-building initiatives in South Asia.

Future work
Addressing mental and physical health together is essential for reducing the burden of multimorbidity. Future efforts should prioritise research on how to implement and scale up integrated mental and physical health care and address contextual barriers to ensure sustainable and equitable health outcomes.