Impact of acute hospitalisation on development of long-term disease and health inequality: a longitudinal population study

ObjectiveTo examine the impact of acute illness on long-term health and describe any differences in these associations between socioeconomic and ethnic groups. DesignLongitudinal population study. SettingLinked primary and secondary care data recorded in the Clinical Practice Research Datalink (CPRD). ParticipantsAdults ([≥]18 years) residing in England registered with a primary care general practice (GP) between 1st January 2012 and 31st December 2022 who have not opted out of inclusion into CPRD and linked data sources. Socioeconomic deprivation was defined using the Index of Multiple Deprivation (IMD) and ethnicity by UK census 2011 definitions. Main outcome measuresThe primary outcome was new long-term disease and multimorbidity (two or more long-term diseases). We describe incidence of hospitalisation for acute illness as the exposure. ResultsWe included 18,329,659 people, with 9,339,394 (51.0%) women, 7,430,555 (40.5%) people from the most deprived deciles (IMD 1-4) and 3,009,717 (16.4%) from a minority ethnic group. 6,038,272 (32.9%) people experienced hospitalisation for acute illness. Hospitalisation was associated with increased onset of long-term disease in those alive at the end of follow up (41.1% hospitalised vs 18.7% not hospitalised; adjusted HR 2.48 (2.47 to 2.48)). Compared to non-hospitalised, those who had been hospitalised were more likely to change from being disease free at baseline to having a new long-term disease (12.9% vs. 7.5%), develop multimorbidity (4.7% vs. 1.1%), or transition to multimorbidity if they had pre-existing disease (8.1% vs. 1.8%). Age-standardised hospitalisation rates were highest in the most deprived decile and in people with Black ethnicity. Comparative hospitalisation ratio for IMD 1 compared to IMD 10 ranging from 1.78 in 2018 to 1.96 in 2021 and for Black ethnicity compared to White ranging from 1.03 in 2017 to 1.08 in 2021. ConclusionsAcute hospitalisation is a key stage in the development of long-term disease and may be an underutilised opportunity for intervention to change healthy life trajectory and reduce health inequality. Summary boxO_ST_ABSWhat is already known on this topicC_ST_ABSO_LIWhilst inequalities in rates of long-term disease are well described, there is little evidence to describing the presence or absence of inequalities in significant acute illness and acute hospitalisation. C_LIO_LIThe consequences of acute hospitalisation for acute illness on development of long-term disease are not well understood. C_LI What this study addsO_LIAcute hospitalisation is strongly associated with subsequent risk of developing long-term disease and multimorbidity. C_LIO_LIAge-standardised hospitalisation rates increased with higher levels of deprivation and was highest for people with Black ethnicity. C_LIO_LIPeople from socioeconomically deprived backgrounds and minority ethnic groups experience a reduced healthy life expectancy following acute hospitalisation. C_LI How this study might affect research, practice, or policyO_LIAcute hospitalisation may be an important marker for inequalities in healthy life expectancy and could be a key opportunity to better manage long-term health to reduce further inequalities. C_LI