Combinations of multiple long-term conditions and risk of hospitalisation and death during the winter season: population-based study of 48 million people in England

BackgroundThe annual winter season poses substantial challenges to the National Health Service (NHS) in England. Hospitalisation and mortality increase during winter, especially in people with multiple long-term conditions (MLTC or multimorbidity). We aimed to describe which combinations of long-term conditions (LTC) are associated with a higher risk of hospitalisation and death during winter amongst adults in England. MethodsIn this population-based study, we used linked primary and secondary care data from the General Practice Extraction Service Data for Pandemic Planning (GDPPR) database, Hospital Episode Statistics, and Office for National Statistics death registry. We included individuals aged [≥]18 years and alive on 1st December 2021 and used overdispersed Poisson models to estimate the incidence rate ratios of all-cause hospitalisations and deaths associated with the combinations of MLTCs - compared to those with no LTC - during the winter season (1 December 2021 to 31 March 2022). FindingsComplete data were available for 48,253,125 adults, of which 15 million (31.2%) had MLTC. Hospitalisation per 1000 person-years was higher in individuals with MLTCs, and varied by combination, e.g.: 96, 1643, and 1552 in individuals with no LTC, cancer+chronic kidney disease (CKD)+cardiovascular disease (CVD)+type 2 diabetes mellitus, and cancer+CKD+CVD+osteoarthritis, respectively. Incidence of death (per 1000 person-years) was 345 in individuals with cancer+CKD+CVD+dementia and 1 with no LTC. CVD+dementia appeared in all the top five MLTC combinations by death and was associated with a substantially higher rate of death than many 3-, 4- and 5-disease combinations. InterpretationRisks of hospitalisation and death vary by combinations of MLTCs and are substantially higher in those with vs. without any LTCs. We have highlighted high-risk combinations for prioritisation and preventive action by policymakers to help manage the challenges imposed by winter pressures on the NHS. FundingNational Institute for Health and Care Research (NIHR) through Health Data Research UK rapid funding call for the research activity "Data Science to inform NHS compound winter pressure policy response" (grant number: HDRUK2022.0313) Research in contextO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed, from inception to April 2023, for published population-based studies examining MLTC combinations in cohorts of adults aged 18 years and over. The search terms were "multimorbidity" or multiple-long-term conditions alongside "groups" or "combinations". We found no previous studies examining MLTC in relation to death or hospitalisation during the winter season. Added value of this studyWe have identified distinct combinations of LTCs and estimated the associated risk of hospitalisation and deaths during the winter season using the whole-population primary and secondary care data in England. Implications of all the available evidenceUnderstanding which combinations of MLTCs are associated with the highest risk of hospitalisation and death allows clinicians and policymakers to prioritise resources for preventative measures, such as vaccination to those that will benefit most during winter seasons.