J Browne, DA Edwards, KM Rhodes, DJ Brimicombe, RA Payne The association of multimorbidity with health service utilisation among patients with dementia in the UK: a population-based study J Browne, DA Edwards, KM Rhodes, DJ Brimicombe, RA Payne

Background Ageing population Increasing prevalence of dementia Changing demands on healthcare and social care funding and service design CSHA = Canadian Study of Health and Aging Canadian Study of Health and Aging

Background It’s not just about “dementia patients” Dementia is commonly associated with additional comorbidities CSHA = Canadian Study of Health and Aging Barnett, Lancet 2012

How do comorbidities impact upon health service utilisation in the dementia population?

Methods Retrospective cohort study CPRD Incident dementia cases diagnosed 2008/9 65 Read codes, including any subtype and unspecified 5-year follow-up minimum 3-months

Methods Barnett, Lancet 2012

Methods Primary care consultations All hospital admissions All primary care prescriptions Time to death

Methods Association between comorbidity count and outcome Negative binomial regression (service use) Cox regression (death) Adjustment for age, gender, practice, dementia treatment, deprivation

Baseline characteristics Comorbidity count 0 or 1 2 or 3 4 or 5 6 or more Number of patients 1071 (21%) 1691 (34%) 1391 (28%) 846 (17%) Female (%) 67% 64% 61% Age, mean (SD) 79.5 (9.2) 81.4 (7.8) 82.0 (7.8) 82.7 (7.0) <80 years (%) 48% 38% 34% 31% 80-89 years (%) 42% 52% 53% 58% ≥90 years (%) 10% 11% 13% Dementia Rx (%) 37% 33% 28% 24%

Prevalence of comorbidities

Primary care consultations Service utilisation Primary care consultations Hospitalisations Prescriptions Comorbidity count Annual rate Rate ratio (95% CI) 0 or 1 15.9 0.81 (0.78-0.85) 0.7 0.88 (0.78-0.99) 51 0.55 (0.52-0.59) 2 or 3 18.4 Ref 85 4 or 5 19.9 1.13 (1.09-1.17) 0.9 1.19 (1.07-1.32) 107 1.34 (1.27-1.43) 6 or more 21.3 1.31 (1.25-1.36) 1.1 1.62 (1.44-1.83) 122 1.68 (1.57-1.81) Mean follow-up 3.0 years

Survival Death rate 12.7 per 100 patient years HR 1.56 (95% CI 1.37-1.78), ≥6 vs. 2-3 comorbidities p<0.001 Age and gender adjusted

Consequences For a woman aged 80-85 years with 6 or more comorbidities, over 3 years: 18 more consultations 131 more prescriptions 2 more hospitalisations Additional cost £5137 (compared to similar individual with 2-3 comorbidities)

Strengths and limitations First such study in UK Large, representative sample Range of relevant outcomes Misclassification of comorbidities varying with health service contact Crude measures of service use Differential loss to follow-up

Conclusions Comorbidities are very common in the context of dementia Comorbidities drive a substantial increase in health service utilisation Multimorbidity must be considered when planning care services for people with dementia