Prevalence, incidence, risk factors and economic burden in multimorbidity among adult Indians: the MILAN cohort study protocol.

INTRODUCTION: Multimorbidity or multiple long-term conditions (MLTCs) are defined as the coexistence of two or more chronic conditions in an individual. With increased longevity and the rising burden of chronic non-communicable diseases (NCDs), multimorbidity is becoming the norm. Although more prevalent in older populations and people with low socio-economic status, multimorbidity is rapidly rising in the younger age groups. Accurate data on its incidence and health and economic impacts, ie, disability-adjusted life years (DALY) lost and quality-adjusted life year (QALY) are not available for the Indian population. The objective of this study is to determine the incidence and predictors of multimorbidity, the longitudinal trends, the common clusters of conditions and the health and economic impact of multimorbidity among adult Indians aged ≥40 years.

METHODS AND ANALYSIS: 12 229 participants (≥40 years) from the population-based cohort, titled the Centre for cArdiometabolic Risk Reduction in South-Asia (CARRS) cohort, from Delhi and Chennai will be recruited. CARRS is an existing adult urban cohort which is well characterised, deeply phenotyped and geocoded with bio-banked samples. They will be followed up longitudinally twice during 2023-2025. Information will be collected on common NCD risk factors (physical inactivity, tobacco and alcohol use), disability, frailty and treatment costs. We will also perform anthropometric and blood pressure measurements on all participants as well as biomarker assessments on a sub-sample of 2300.

ETHICS AND DISSEMINATION: Ethics approval has been obtained from the ethics committees of the Centre for Chronic Disease Control (CCDC) (Institutional Review Board (IRB) 00006330) and the Madras Diabetes Research Foundation (IRB no. IRB00002640). Key findings from the study will be published in national and international peer-reviewed journals. Results will also be presented at various academic conferences to engage with the broader research community. A final report will be submitted to the funding agency upon completion of the fellowship. De-identified data will be securely stored at the CCDC. Access to the data will be available upon request to the principal investigator.