title: Association of comorbidity and health service usage among patients with dementia in the UK: a population-based study.
abstract: The majority of people with dementia have other long-term diseases, the presence of which may affect the progression and management of dementia. This study aimed to identify subgroups with higher healthcare needs, by analysing how primary care consultations, number of prescriptions and hospital admissions by people with dementia varies with having additional long-term diseases (comorbidity).
  
  
  
  A retrospective cohort study based on health data from the Clinical Practice Research Datalink (CPRD) was conducted. Incident cases of dementia diagnosed in the year starting 1/3/2008 were selected and followed for up to 5 years. The number of comorbidities was obtained from a set of 34 chronic health conditions. Service usage (primary care consultations, hospitalisations and prescriptions) and time-to-death were determined during follow-up. Multilevel negative binomial regression and Cox regression, adjusted for age and gender, were used to model differences in service usage and death between differing numbers of comorbidities.
  
  
  
  Data from 4999 people (14 866 person-years of follow-up) were analysed. Overall, 91.7% of people had 1 or more additional comorbidities. Compared with those with 2 or 3 comorbidities, people with ≥6 comorbidities had higher rates of primary care consultations (rate ratio (RR) 1.31, 95% CI 1.25 to 1.36), prescriptions (RR 1.68, 95% CI 1.57 to 1.81), and hospitalisation (RR 1.62, 95% CI 1.44 to 1.83), and higher risk of death (HR 1.56, 95% CI 1.37 to 1.78).
  
  
  
  In the UK, people with dementia with higher numbers of comorbidities die earlier and have considerably higher health service usage in terms of primary care consultations, hospital admissions and prescribing. This study provides strong evidence that comorbidity is a key factor that should be considered when allocating resources and planning care for people with dementia.
authors.affiliation: Department of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.|Primary Care Unit, University of Cambridge, Cambridge, UK.
authors.forename: Jorge
authors.initials: J
authors.lastname: Browne
authors.affiliation: Primary Care Unit, University of Cambridge, Cambridge, UK.|Grove Lane Surgery, Thetford and National Institute for Health Research Doctoral Research Fellow at Primary Care Unit, University of Cambridge, Worts Causeway Cambridge, UK.
authors.forename: Duncan A
authors.initials: DA
authors.lastname: Edwards
authors.affiliation: Grove Lane Surgery, Thetford and National Institute for Health Research Doctoral Research Fellow at Primary Care Unit, University of Cambridge, Worts Causeway Cambridge, UK.
authors.forename: Kirsty M
authors.initials: KM
authors.lastname: Rhodes
authors.affiliation: Primary Care Unit, University of Cambridge, Cambridge, UK.|Primary Care Unit, University of Cambridge, Cambridge, UK.
authors.forename: D James
authors.initials: DJ
authors.lastname: Brimicombe
authors.affiliation: Primary Care Unit, University of Cambridge, Cambridge, UK.|Centre for Academic Primary Care, University of Bristol, Bristol, UK.
authors.forename: Rupert A
authors.initials: RA
authors.lastname: Payne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D000071069:Multiple Chronic Conditions / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D018401:Sample Size; D006113:United Kingdom / Q000453:epidemiology
keywords: HEALTH SERVICES ADMINISTRATION & MANAGEMENT; PRIMARY CARE; Service Use; comorbidity; multimorbidity