Characteristics, service use, and mortality of clusters of multimorbid patients in England: a population-based study

Abstract

BackgroundMultimorbidity is a major challenge facing health systems. To help understand the changes to services and policies that are required, we investigated which diseases co-occur and which combinations lead to the highest mortality and service use. MethodsFor this population-based study, we used linked primary and secondary care electronic health records contributed by general practices in England to the Clinical Practice Research Datalink (CPRD). The study includes all multimorbid adults (aged ≥18 years) with two or more predefined long-term health conditions. For the primary objective, latent class analysis, stratified by age groups, was used to identify multimorbidity clusters using a random set of 80% of the multimorbid patients, with consistency of results checked in the remaining 20%. Associations between multimorbidity clusters, demographics and primary outcomes (hospitalisation, polypharmacy and mortality) were quantified using generalised linear models as the secondary objective. This study was approved by the CPRD Independent Scientific Advisory Committee and is covered by their ethical approval. FindingsWe included all adult patients with multimorbidity (n=113 211) from a random sample of the CPRD data (n=391 669). Physical–mental health co-morbidity and respiratory disease and multimorbidity clusters were common across all age strata. In people younger than 65 years, the substance misuse and mental illness co-morbidity cluster (<7% prevalence; consisted mostly of male, current smokers and patients from deprived areas) had the highest demographic-adjusted 5-year mortality rate (in the age 45–64 years strata, the adjusted odds ratio was 1·08 [95% CI 1·07–1·10]) despite low health service use. Cardiovascular-related clusters were prevalent in people aged 65 years or older, in whom the cluster chronic pain, cardiovascular disease, and mental illness (age 65–84 years strata) had the highest number of primary care consultations in 1 year (median 23 [IQR 14–35]) and 5-year mortality (39%). In the 85 years and older age strata, patients in the low service use multimorbidity cluster had the lowest number of morbidities (median 3 [2–4]), service use, and mortality. Across identification and validation data, results showed consistency between obtained disease profiles, similar classification quality, and similar relationships between patient clusters, demographic characteristics, and primary outcomes. InterpretationInterventions and policies to improve the care of patients with multimorbidity might be more effective when targeted at the distinct clusters of multimorbidity that we have highlighted. Results may be further strengthened by validation in external databases. FundingMRC Career Development Award (MR/P021573/1).