(22) Incident Dementia Identified by Redeemed Prescriptions Recorded in The Danish National Prescription Registry

Sunday, August 28, 2022

8:00 AM – 1:45 PM CEST

Location: Hall C

Publication Number: 1067

Presenting Author(s)

Cecilia H. Fuglsang
– Department of Clinical Epidemiology, Aarhus University, Aarhus N, Midtjylland, Denmark

Co-Author(s)

Nils Skajaa
– 8200 Aarhus N, Midtjylland, Denmark
Péter Szentkúti
– Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark, Denmark
Erzsebet Horvath-Puho
– Aarhus N, Midtjylland, Denmark
Henrik Toft Sørensen, MD, PhD, DMSc, DSc
– Professor & Chair, Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark, Midtjylland, Denmark
Victor Henderson
– Professor, Departments of Epidemiology & Population Health and Neurology & Neurological Sciences, Stanford University, Stanford, CA, United States

Background: The Danish National Patient Registry (DNPR) and the Danish Psychiatric Central Research Registry (DPCRR), covering all Danish hospitals, are widely used to identify all citizens who have been diagnosed with dementia in a hospital setting. Private practicing neurologists or psychiatrists may also treat patients with dementia. Therefore, the DNPR and DPCRR may be incomplete regarding dementia registration. However, it is possible that patients treated in private care can be identified by data on prescriptions for dementia treatment.

Objectives: To examine the cumulative incidence of receiving an incident dementia diagnosis in the DNPR or DPCRR after redeeming an incident prescription for dementia treatment.

Methods: We conducted a population-based cohort study from 2000-2018 using individual-level data from Danish medical registries. The Danish National Prescription Registry was used to identify individuals (≥40 years) with a first-time redeemed prescription of memantine or an acetylcholinesterase inhibitor. Individuals with an ICD diagnosis of dementia registered in the DNPR or the DPCRR prior to, or on, the date of the redeemed prescription were excluded. We followed these individuals from date of redemption of their prescription until an inpatient or outpatient diagnosis of dementia recorded in the DNPR or DPCRR, death, emigration, 5 years of follow-up, or end of study period, whichever came first. The cumulative incidence with 95% confidence interval (95% CI) of a dementia diagnosis in the DNPR was calculated after 6 months, 1 year, and 5 years, treating death as a competing risk.

Results: A total of 16,852 individuals (54% female) were identified with a prescription redemption during the study period. Median age was 79 years (interquartile range: 73-84). Of these, 2,009 (12%) had redeemed a prescription of memantine and 14,843 (88%) a prescription of an acetylcholinesterase inhibitor. The cumulative incidence of a diagnosis of dementia was 16% (95% CI: 16-17%) after 6 months, 25% (95% CI: 24-25) after 1 year, and 56% (95% CI: 55-57%) after 5 years. The 5-year mortality was 54% (95% CI: 53-55%).

Conclusions: After five years, only 56% of patients redeeming a prescription of memantine or an acetylcholinesterase inhibitor were identified in the DNPR or DPCCR with an inpatient or outpatient diagnosis of dementia. This finding may be explained by high mortality among dementia patients, absence of any hospital encounter resulting in a primary or secondary dementia diagnosis, and the prescription of dementia medications for non-approved indications.