Equity dynamics of multimorbidity in England over time: a descriptive study on trends of incident and prevalent multimorbidity by age, sex, and socioeconomic status

Date of Approval: 
2019-08-22 00:00:00
Lay Summary: 
In the UK, an increasing number of people are living with multiple chronic conditions (multimorbidity), such as with diabetes, heart disease and dementia. Those from socioeconomically deprived backgrounds are more affected, and more likely to develop multiple conditions at earlier ages. Individuals with multiple conditions tend to have worse health, multiple medications, and often experience discontinuity of care. Multimorbidity is also a problem for health systems, which are focused around the care of single conditions. Although associated with ageing, many people of working age also live with multimorbidity. Current studies have not looked at how multimorbidity in the English adult population has changed in recent years. This study will look at the number of patients with multiple long-term conditions between 2004-2018 to see how trends have changed over time, as well as by age, gender, and socioeconomic status. We are particularly interested in multimorbidity with three or more chronic conditions that affect three or more body systems, as this is considered an indicator of poorer health and greater healthcare usage. We will also look for patterns in the age of onset of multimorbidity and the time between developing a first disease and then subsequent conditions. Describing these patterns will help us see how multimorbidity accumulates over the life-course and how this has evolved over time, and therefore can help to identify areas for focusing prevention efforts.
Technical Summary: 
Background: Multimorbidity is becoming increasingly prevalent in the UK, with higher burden of disease and earlier onset among the more socioeconomically deprived. Multimorbidity poses unique challenges to the provision of primary care and the structure of healthcare systems currently focused around single conditions. Few studies have looked at multimorbidity incidence, trajectories of accumulation, or equity trends over time in England, and those that have tend to focus on older subsets of the population. Furthermore, the majority of studies have used a definition of coexistence of 2 or more diseases from varying predefined lists of chronic conditions. Objective: to describe the current patterns of coexistence of multiple conditions treated in primary care over the life-course and over time, and how these patterns vary by socioeconomic status Methods: Two measures of multimorbidity will be used throughout: a) basic multimorbidity: two or more chronic conditions; b) complex multimorbidity: at least three chronic conditions affecting at least three body systems. CPRD data will be linked to the English Index of Multiple Deprivation 2010 to allow analyses by socioeconomic status. The first stage of this observational descriptive cohort study will calculate the observed incidence and prevalence of multimorbidity by sex, age group, and socioeconomic status over the time period of 2004-2018. We will calculate the median age of onset of initial condition and multimorbidity, along with the median accumulation time from first condition diagnosis to onset of multimorbidity. In the second stage of the study, we will use survival analysis (parametric or semi-parametric frailty models) to calculate the modelled incidence and prevalence of multimorbidity by sex, age group, and socioeconomic status. Parametric or semi-parametric frailty models will also be used to map trends in age of onset of first incident condition and time of subsequent progression to multimorbidity by sex, socioeconomic status, and initial condition. Primary outcomes: incidence and prevalence of multimorbidity. Secondary outcomes will include: a) age of onset of 1st condition, b) age of onset of multimorbidity, c) time between onset of 1st condition and onset of multimorbidity.
Health Outcomes to be Measured: 
Primary outcomes: incidence and prevalence of basic multimorbidity (two or more chronic conditions); incidence and prevalence of complex multimorbidity (three or more chronic conditions in three or more body systems). Secondary outcomes include: a) age of onset of 1st condition; b) age of onset of basic multimorbidity; c) age of onset of complex multimorbidity; d) time from onset of 1st disease to onset of basic multimorbidity; e) time from onset of 1st disease to onset of complex multimorbidity; f) number of chronic conditions All analyses will be stratified by sex, age group, and quintile of the English Index of Multiple Deprivation (IMD) 2010 (as a measure of socioeconomic status).
Application Number: 

Kate Fleming - Chief Investigator - University of Liverpool
Anna Head - Corresponding Applicant - University of Liverpool
Chris Kypridemos - Collaborator - University of Liverpool
Martin O'Flaherty - Collaborator - University of Liverpool
Pieta Schofield - Collaborator - University of Liverpool

Patient Level Index of Multiple Deprivation