Using real‐world general practitioner data to study the diagnosis and management of dementia: rationale and design

Background General practitioners (GPs) play a critical role in the early recognition of cognitive deficits and management of dementia. Timely diagnosis is important in light of potential disease‐modifying therapies and the potential to improve patient outcomes. We aimed to establish a real‐world data cohort utilizing data from GPs on individuals with dementia as a starting point, with the goal of gaining valuable insights into trajectories and management of dementia and patient outcomes. Here we describe the rationale and design. Method We selected individuals with dementia using Dutch GP data from the PHARMO Data Network, which includes diagnoses, symptoms, examinations, prescriptions, and communication between GPs and specialists. Diagnosis of dementia was defined as a diagnosis code or prescription of anti‐dementia drugs between January 1, 2011 and December 31, 2020. Persons were included if they had one year of history prior to dementia diagnosis. We described the cohort in terms of demographics and screening tests for cognitive impairment. Result A total of 52,911 individuals with dementia were selected from a source population of 4.7 million persons. The mean age was 81 years (standard deviation [SD] = 8.65) and 31,343 (59%) were female (Table 1). On average, patients have 8.6 years (SD = 4.09) of data available prior to dementia diagnosis and can be followed‐up for 2.8 years (SD = 2.19) after diagnosis. The reason for end of follow‐up was death for 16,978 persons (32%), end of data availability for 21,314 persons (40%), and 14,699 (28%) reached December 31, 2020 and are still registered (i.e., active). We found the Mini‐Mental State Examination (MMSE) in GP records of 31,759 persons (60%), and the Montreal Cognitive Assessment (MoCA) and Rowland Universal Dementia Assessment Scale (RUDAS) for only 1,777 (3%), and 29 persons (