Therapeutic Chemical (ATC) codes. We considered as treated those patients who had a prescription or billing for anticholinesterases (N06DA) or memantine (N06D × 01). We used outcomes recorded in SIDIAP to describe dementia assessment in the Catalan primary-care system, because clinical practice might influence the identification of dementia cases, and this would affect estimates of prevalence and incidence rates.10,14 In particular, we identified the number of persons who were institutionalized, attended by the home-care program, had a record of cognitive assessment, or had a record of functional ability and independence assessment. Cognitive assessment was defined as at least one Mini-Mental Status Examination15 or Pfeiffer test16 (Spanish versions) score ≤23 or ≥3, respectively, considered to suggest cognitive impairment. Assessment of functional ability and independence was defined as at least one recorded score on the Barthel Index,17 Lawton Scale,18 Katz Index,19 or Blessed Dementia Rating Scale.20 Low functional ability or dependence was considered when the score was 1 million cases provides a comprehensive update of the epidemiology of dementia in southern Europe. Our findings highlighted that records of dementia diagnoses routinely collected in primary care and registered in SIDIAP are accurate enough to be used for research purposes. Moreover, we provided a detailed update about crude and standardized prevalence and incidence rates, which may help to improve policies related to dementia not only in primary-care settings but also in secondary care. Validation of dementia diagnoses We found a 91% PPV of diagnoses of dementia recorded in SIDIAP. Sensitivity analyses showed that in the worst scenario, the PPV would be 77.8%. Our PPV estimate was slightly higher than values observed in previous studies that assessed the quality of routinely collected data on dementia in primary-care services for research purposes.10,24,25 When routinely collected electronic health records are applied to research, avoiding false-positive diagnoses could be more important than avoiding false negatives. In longitudinal studies, for example, false positives can dilute observed effects and reduce statistical power.26 Our results highlighted that false positives on dementia cases are scarce in SIDIAP and that patients having a record in SIDIAP of a diagnosis of dementia are very likely to have the disease. Therefore, the SIDIAP database is valid for epidemiological research on dementia. Incidence and prevalence We estimated an age- and sex-standardized incidence of 8.6/1,000 person-years (95% CI 8.0–9.3), similar to the adjusted incidence estimated by the NEDICES study on the Spanish population aged ≥65 years.27 Other studies conducted in Spain have reported disparate estimates of dementia incidence.28,29 However, differences in study populations and methodologies limit comparability with our findings. When comparing incidence of dementia according to age-group, our estimations were similar to those reported by BermejoPareja et al27 and Lobo et al28 in all age-groups except the oldest old (aged at least 85 years), in which our values were lower than the face-to-face studies cited. This disparity might be partially due to some level of underrecording in SIDIAP, mainly concentrated in the oldest-old patients, in line with previous studies.30 Some general practitioners may consider memory difficulties part of the normal aging process, rather than a disability that requires specialist care and support,31 while others might be reluctant to use dementia codes in this age-group because they consider the diagnosis and treatment of dementia useless.8,31 We estimated the age- and sex-standardized prevalence of dementia as 5.1% (95% CI 4.5%–5.7%), which overlapped with the standardized estimations reported by the the most recent face-to-face studies in the Spanish population at least 65 years old.4,5 Previous face-to-face studies – mostly conducted before 2010 – reported crude prevalence estimates, ranging from 5.5% to 14.9% in Spanish people aged ≥65 Clinical Epidemiology downloaded from https://www.dovepress.com/ by 76.229.153.206 on 05-Dec-2021 For personal use