Individual healthy aging indices, measurements and scores.

The positive gerontological approach to aging has resulted in successive terminologies to describe the process of aging, including successful aging, active aging, healthy aging, or healthy and active aging, amongst others. Each definition proposed by geriatricians, psychologists, sociologists or public health specialists has been based on specific aspects of aging that are most important to the authors' discipline, explaining the current difficulty in determining which is the best set of criteria to determine "good aging". Two successive analyses of the measurements used in longitudinal studies from 1989 to 2018 testify to this heterogeneity in the types of questions proposed to evaluate the quality of the individual aging process. To confront this complexity, new and integrated indices have successively been proposed to quantify and qualify the survival period of aging individuals. The present paper aims to describe and compare the value of the "healthy aging index", the "modified healthy aging index", the "healthy aging score" and the "selfie aging test". Attempts to date to identify the best individual measurement of "aging well" have been interesting, and certainly show promise, but their limitations to specific populations call for more concerted effort from the scientific community to obtain worldwide validation. Another option would be to identify the best self-assessment questionnaire and include it in a mobile device, enabling longer term personal follow-up of aging functions. There is a clear lack of data of this type at present, and an urgent need to obtain such information, to enable early and targeted interventions.