affected by dementia is expected to increase to 131 million in 2050, resulting in huge social and economic costs.1 Population-based epidemiological estimates of its prevalence and incidence is crucial to plan and budget health services and evaluate its economic burden. Therefore, robust and up-to-date estimates are needed to support the creation of useful public policies on dementia.2 However, updated estimates of prevalence and incidence in the European population are scarce,1 eg, in Spain, most of the studies collected data in the 1990s or 2000s, and to our knowledge, only four used data collected during the past 10 years.3–6 High economic costs of door-to-door surveys or questionnaire-based studies may contribute to the difficulty of updating estimates of prevalence and incidence of dementia. Correspondence: Rafel Ramos Vascular Health Research Group (ISVGirona) IDIAPJGol, c/ Maluquer Salvador, 11 Baixos, Girona 17002, Catalonia, Spain Tel +34 97 248 7968 Email rramos.girona.ics@gencat.cat Journal name: Clinical Epidemiology Article Designation: ORIGINAL RESEARCH Year: 2019 Volume: 11 Running head verso: Ponjoan et al Running head recto: Ponjoan et al DOI: http://dx.doi.org/10.2147/CLEP.S186590 Clinical Epidemiology downloaded from https://www.dovepress.com/ by 76.229.153.206 on 05-Dec-2021 For personal use only. Powered by TCPDF (www.tcpdf.org) Clinical Epidemiology 2019:11 submit your manuscript | www.dovepress.com Dovepress Dovepress 218 Ponjoan et al Electronic health records emerged as a new opportunity to study the epidemiology of dementia: prevalence and incidence-rate estimates can be updated at low cost using data routinely collected in health care settings. Indeed, the use of electronic medical databases to assess the epidemiology of dementia has been increasing at the European level7 and in many developed countries, such as Canada8 and the Netherlands.9 However, the accuracy of dementia records in routinely collected health care data sets is always a concern, and cohorts should ideally conduct their own setting-specific validation.10 This concern is especially apparent for electronic health records collected in primary care, because accuracy of dementia diagnoses recorded by general practitioners has been considered low.8,11 Nevertheless, a recent systematic review reported high positive predictive values (PPVs) (0.83 or higher) when identifying dementia cases in primary-care data, indicating that dementia codes in those primary-care databases were sufficiently accurate to be used for research purposes.10 We thus used data from a large primary-care database to describe the epidemiology of dementia in Catalonia, southern Europe. First, we assessed the validity of dementia diagnoses recorded in the database to determine if they could be used for research purposes. Then, we estimated crude and standardized prevalence and incidence rates of dementia in Catalonia in 2016, in order to update the epidemiological estimates. Methods This population-based study was approved by the Clinical Research Ethics Committee, Primary Care Research Institute – IDIAP Jordi Gol. Data were obtained from the System for the Development of Research in Primary Care (SIDIAP) database, which contains routine records of consultations from ~275 general-care practices belonging to the National Health Service of Catalonia (Institut Català de la Salut). SIDIAP contains anonymized longitudinal medical records containing data on demographics, symptoms, diagnoses, and prescriptions for about 6 million people (>80% of the Catalan population, 15% of the Spanish population).12,13 We defined dementia diagnoses using the following codes from the International Classification of Diseases, Tenth revision (ICD10): dementia in Alzheimer’s disease (F00), vascular dementia (F01), dementia in other diseases classified elsewhere (F02.8), unspecified dementia (F03), Alzheimer’s disease (G30), Lewy body disease (G31.8), or frontotemporal dementia (G31.0). SIDIAP is linked with the pharmacyinvoicing database provided by the National Health Service of Catalonia and medications are recorded using the Anatomical