Resource utilisation, costs and clinical outcomes in non-institutionalised patients with Alzheimer's disease: 18-month UK results from the GERAS observational study

Abstract

Background: Alzheimer's disease (AD), the commonest cause of dementia, represents a significant cost to UK society. This analysis describes resource utilisation, costs and clinical outcomes in non-institutionalised patients with AD in the UK.

Methods: The GERAS prospective observational study assessed societal costs associated with AD for patients and caregivers over 18 months, stratified according to baseline disease severity (mild, moderate, or moderately severe/severe [MS/S]). All patients enrolled had an informal caregiver willing to participate in the study. Healthcare resource utilisation was measured using the Resource Utilization in Dementia instrument, and 18-month costs estimated by applying unit costs of services and products (2010 values). Total societal costs were calculated using an opportunity cost approach.

Results: Overall, 526 patients (200 mild, 180 moderate and 146 MS/S at baseline) were recruited from 24 UK centres. Mini-Mental State Examination (MMSE) scores deteriorated most markedly in the MS/S patient group, with declines of 3.6 points in the mild group, 3.5 points in the moderate group and 4.7 points in the MS/S group; between-group differences did not reach statistical significance. Patients with MS/S AD dementia at baseline were more likely to be institutionalised (Kaplan-Meier probability 28% versus 9% in patients with mild AD dementia; p < 0.001 for difference across all severities) and had a greater probability of death (Kaplan-Meier probability 15% versus 5%; p = 0.013) at 18 months. Greater disease severity at baseline was also associated with concomitant increases in caregiver time and mean total societal costs. Total societal costs of £43,560 over 18 months were estimated for the MS/S group, versus £25,865 for the mild group and £30,905 for the moderate group (p < 0.001). Of these costs, over 50% were related to informal caregiver costs at each AD dementia severity level.

Conclusions: This study demonstrated a mean deterioration in MMSE score over 18 months in patients with AD. It also showed that AD is a costly disease, with costs increasing with disease severity, even when managed in the community: informal caregiver costs represented the main contributor to societal costs.

Keywords: AD dementia severity; Alzheimer’s disease; Clinical outcomes; MMSE; Resource use; Societal costs.

Fig. 1

Patient disposition at 18 months according to baseline AD dementia severity group AD Alzheimer’s disease, MS/S moderately severe/severe

Fig. 2

Change in MMSE score from baseline to 18 months stratified according to baseline AD dementia severity. AD, Alzheimer’s disease, MMSE Mini-Mental State Examination. Data are presented as least square means with 95% confidence intervals from mixed-model repeated measures analysis adjusted for baseline MMSE score. Change-from-baseline data missing for 0–9.0, 1–11.0 and 3.0–12.0% of patients across AD dementia severity groups at 6, 12 and 18 months, respectively

Fig. 3

AD dementia status at 18 months stratified according to baseline severity. AD, Alzheimer’s disease, MMSE Mini-Mental State Examination. Percentages and patient numbers (n) shown exclude deaths and institutionalised patients

Fig. 4

Caregiver time for activities of daily living stratified by baseline AD dementia severity. AD Alzheimer’s disease, ADL activities of daily living, MS/S moderately severe/severe. All values are based on data provided for the last month before each visit. The value beside each bar is the mean overall monthly caregiver time; this is not the sum of the three components of caregiver time because caregiver time was capped at 720 h/month. The n value is the number of respondents (0–9.0% missing). SD ranges observed across each individual endpoint at all time points and AD dementia severities were as follows: Overall time, 192–263 h; Supervision time, 120–269 h; Basic ADL, 59–138 h; Instrumental ADL, 83–150 h

Fig. 5

Estimated mean total societal costs of AD stratified according to baseline AD dementia severity, per patient. AD Alzheimer’s disease, ANOVA analysis of variance, MS/S moderately severe/severe. An opportunity cost approach was used for working and non-working caregivers; supervision time was excluded from caregiver time. Missing data were imputed at both the total societal cost and cost item level. The value above each column gives the mean total 18-month overall societal costs. This value is not the sum of the individual components as total societal costs were imputed separately from the imputation method used on the three cost components. *ANOVA p-value for comparison between AD dementia severity groups for total societal costs