Extreme Longevity Areas: Redefining the Need for A Transparent and Standardized Framework.

The concept of extreme longevity areas, geographically circumscribed areas with an extremely high prevalence of centenarians compared with surrounding regions, has attracted increasing scientific and public attention in recent decades. The Extreme Longevity Index (ELI), based on birth-cohort survival, is the main operational metric currently used to identify such areas. However, its application remains highly heterogeneous, and no standardized and transparent framework exists for the robust and reproducible characterization of extreme longevity patterns. In this commentary, we identify key methodological limitations in current approaches and argue for the need to strengthen the conceptual basis of this field. These limitations include insufficiently defined population denominators, variability in the handling of migrations, inconsistent spatial analytical approaches, lack of agreed thresholds for defining extreme values, limited specification of appropriate observation periods, and variable standards of registry quality and age validation. We further argue that a more robust approach should incorporate mechanisms for periodic reassessment, broader demographic profiling beyond centenarians alone, and clearer definitions of territorial continuity. In the absence of such methodological standardization, the validity and comparability of reported extreme longevity areas remain uncertain, including the calculations used to characterize previously described regions. Establishing a coherent and transparent framework is therefore necessary to strengthen the scientific foundations of this field.