Inequalities in incident and prevalent multimorbidity in England, 2004–19: a population-based, descriptive study

BACKGROUND: The increasing burden of multimorbidity and its socioeconomic gradient poses unique challenges to the provision and structure of health care. We aimed to describe inequalities and trends over time in multimorbidity prevalence, incidence, and case fatality among adults of all ages in England using primary care electronic health records. METHODS: We used a random sample of 991 243 individuals from the Clinical Practice Research Datalink Aurum database registered at participating general practices within England between Jan 1, 2004, and Dec 31, 2019, linked to the 2015 English Index of Multiple Deprivation (IMD). We used the following two outcome measures: basic multimorbidity, comprising two or more chronic conditions; and complex multimorbidity, comprising at least three chronic conditions affecting at least three body systems. We calculated crude, age-standardised, and age-sex-standardised annual incidence, prevalence, and case fatality rates, along with median age of onset for both multimorbidity types. We calculated absolute and relative inequalities for each outcome. FINDINGS: In 2004, 30·8% of our study population had basic multimorbidity and 15·1% had complex multimorbidity. This increased to 52·8% and 32·7%, respectively, in 2019. Although the overall incidence of basic multimorbidity remained stable over the 16-year study period, the incidence among people of working age and the incidence of complex multimorbidity increased gradually. Socioeconomic deprivation was associated with an increased incidence of both multimorbidity types in working-age adults. The median age at onset of complex multimorbidity was 7 years younger for the most deprived quintile of the IMD compared with the least deprived quintile. INTERPRETATION: The burden of multimorbidity in England has increased substantially over the past 16 years with persistent inequalities, which are worse in working-age adults and for complex multimorbidity. Prevention efforts to reduce the onset and slow the progression of multimorbidity are essential to reduce the increasing impact on patients and health systems alike. FUNDING: University of Liverpool and UK National Institute for Health Research School for Public Health Research.