Health care resource utilisation in primary care prior to and after a diagnosis of Alzheimer's disease: a retrospective, matched case-control study in the United Kingdom

Abstract

Background: This study examined medical resource utilisation patterns in the United Kingdom (UK) prior to and following Alzheimer's disease (AD) diagnosis.

Methods: A patient cohort aged 65 years and older with newly diagnosed AD between January 2008 and December 2010 was identified through the UK's Clinical Practice Research Datalink (CPRD). Patients with a continuous record in the CPRD (formerly the General Practice Research Database [GPRD]) for both the 3 years prior to, and the 1 year following, AD diagnosis were eligible for inclusion. A control cohort was identified by matching general older adult (GOA) patients to patients with AD based on year of birth, gender, region, and Charlson Comorbidity Index at a ratio of 2:1. Medical resource utilisation was calculated in 6-month intervals over the 4-year study period. Comparisons between AD and GOA control cohorts were conducted using conditional logistic regression for patient characteristics and a generalised linear model for resource utilisation.

Results: Data for the AD cohort (N = 3,896) and matched GOA control cohort (N = 7,792) were extracted from the CPRD. The groups were 65% female and the AD cohort had a mean age of 79.9 years (standard deviation 6.5 years) at the date of diagnosis. Over the entire study period, the AD cohort had a significantly higher mean primary care consultation rate than the GOA cohort (p < .0001). While the GOA cohort primary care consultation rate gradually increased over the 4-year period (ranging from 5 to 7 consultations per 6-month period), increases were more pronounced in the AD cohort (ranging from 6 to 11 consultations per 6-month period, peaking during the 6-month periods immediately prior to and post diagnosis). The AD cohort also had a higher overall specialty referral rate than the GOA cohort over the 4-year period (37% vs. 25%, respectively; p < .0001); the largest difference was during the 6 months immediately prior to AD diagnosis (17% vs. 5%, respectively; p < .0001).

Conclusions: In the UK, AD diagnosis is associated with significant increases in primary and secondary care resource utilisation, continuing beyond diagnosis. This evidence may be important to health care commissioners to facilitate effective mobilisation of appropriate AD-related health care resources.

Figure 1

Patient data identification from the CPRD. Clinical Practice Research Datalink (CPRD) records identified patients with Alzheimer’s disease (AD) diagnosed between 01 January 2008 and 31 December 2010, and a matched general older adult (GOA) cohort. Excluding ineligible patients produced a cohort of 8,114 patients; 3,911 had continuous CPRD records throughout the 4-year study period and 3,896 were matched 1:2 with 7,792 GOA controls by birth year, gender, region, and comorbidity.

Figure 2

Mean numbers of consultations per person. For total consultations, AD vs. GOA comparisons were significant (p < .0001) at every time interval. The x-axis values represent 6-month intervals pre- and post-index (AD diagnosis) date. AD = Alzheimer’s disease; GOA = general older adult; GP = general practise.

Figure 3

Proportion of patients with at least one new specialty referral. For total secondary care specialty referrals, AD vs. GOA comparisons were significant (p < .02) at every time interval except the second post-index interval. The x-axis values represent 6-month intervals pre- and post-index (AD diagnosis) date. AD = Alzheimer’s disease; GOA = general older adult.

Figure 4

Proportion of patients with at least one prescription for an AChE inhibitor. For total AChE inhibitor prescriptions, AD vs. GOA comparisons were significant (p < .0001) at every time interval. The x-axis values represent 6-month intervals pre- and post-index (AD diagnosis) date. AChE = acetylcholinesterase; AD = Alzheimer’s disease; GOA = general older adult.

Figure 5

Proportion of patients with at least one hospital admission. HES-eligible patients included n = 1,785 for the AD cohort and n = 3,407 for the GOA cohort. For AD vs. GOA comparisons, *p ≤ .01 and **p < .0001. The x-axis values represent 6-month intervals pre- and post-index (AD diagnosis) date. AD = Alzheimer’s disease; GOA = general older adult; HES = Hospital Episode Statistics.