Registry-Based Dementia Incidence in Argentina: A Nationwide, Decade-Long Analysis by Age, Sex, and Etiology

Background: National data on dementia incidence is scarce in low- and middle-income countries, limiting public health surveillance and planning. In Argentina, no nationwide estimates of dementia incidence exist despite rapid population aging. Administrative disability registries do not capture clinical disease onset; rather, they record certification events and therefore provide a registry-based proxy for population-level dementia surveillance in settings without prospective incidence cohorts. Methods: We conducted a population-based registry study using data from Argentina’s National Registry of Persons with Disabilities between 2016 and 2022, excluding pandemic-disrupted years (2020–2021). Incident registry entries with dementia recorded as the primary cause of disability were identified using ICD-10 codes for Alzheimer's disease and related disorders (ADRD), vascular dementia, and other etiologies. Crude and age-standardized incidence (ASI) of dementia certification per 100,000 inhabitants were estimated by sex, age group, dementia subtype, and early- (<65 years) versus late-onset (≥65 years) dementia. Pre-specified sensitivity analyses quantified capture fraction against regional cohorts and adjusted temporal trends for an exogenous proxy of registry maturation. Results: In 2022, the registry-based crude dementia incidence was 47.7 per 100,000 inhabitants (95% CI: 46.6–48.7). Crude incidence was higher in women than men, whereas age-standardized incidence was comparable between sexes (48.1 vs. 45.5 per 100,000). Incidence increased steeply with age, from 0.9 per 100,000 at ages 40–45 to nearly 480 per 100,000 among individuals aged ≥95 years. ADRD predominated from approximately 55–60 years onward, while other etiologies were relatively more frequent at younger ages. Late-onset dementia incidence (≥65 years) was substantially higher than early-onset dementia (<65 years) (130.9 vs. 6.3 per 100,000). Provincial age-standardized rates varied from 4.7 to 137.7 per 100,000, and were strongly associated with care access metrics. Between 2016 and 2022, age-standardized incidence increased significantly (p<0.001); however, capture fractions of 6 to 12% relative to regional cohorts and a 45% attenuation of the temporal coefficient after adjustment for registry maturation. Conclusions: This study provides the first nationwide characterization of registry-based dementia certification incidence in Argentina. Distinct age-, sex-, and etiology-specific patterns highlight different epidemiological scenarios for early- and late-onset dementia. Because these estimates reflect administrative certification rather than clinical disease onset and are subject to differential ascertainment, they should be interpreted as a lower bound of true incidence; nonetheless, they constitute a feasible and informative surveillance approach for countries lacking national clinical registries and can support health system planning and prevention strategies.