title: 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.
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis IN 46285, USA. chen_lei_lc@lilly.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Catherine
authors.initials: C
authors.lastname: Reed
authors.forename: Michael
authors.initials: M
authors.lastname: Happich
authors.forename: Allen
authors.initials: A
authors.lastname: Nyhuis
authors.forename: Alan
authors.initials: A
authors.lastname: Lenox-Smith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D016022:Case-Control Studies; D015331:Cohort Studies; D003695:Delivery of Health Care / Q000706:statistics & numerical data* / Q000639:trends; D057286:Electronic Health Records / Q000639:trends; D005260:Female; D006295:Health Resources / Q000706:statistics & numerical data* / Q000639:trends; D006760:Hospitalization / Q000639:trends; D006801:Humans; D015994:Incidence; D008297:Male; D011320:Primary Health Care / Q000706:statistics & numerical data* / Q000639:trends; D012017:Referral and Consultation / Q000706:statistics & numerical data* / Q000639:trends; D012189:Retrospective Studies; D006113:United Kingdom / Q000453:epidemiology