Assessment of AHA

Initially, AHA was assessed with a biomedical model based on the Rowe and Kahn model (AHA-B) and the biopsychosocial AHA definition based on the WHO criteria (AHA-BPS). The variables to characterize the two models were extracted from 7 of the 22 SHARE modules: physical health, cognitive function, handgrip strength, mental health, social support, activities, and financial resources.

The AHA-B model was operationalized according to McLaughlin et al. [17], as modified by Hank according to the variables available to SHARE [15]. A person fulfils AHA criteria if 3 conditions are met: (a) no disease, no disability; (b) high cognitive and physical functioning; (c) active engagement in society. Each condition is operationalized with the following indicators [15]:

Absence of major diseases. No doctor has ever told the respondents they have cancer, chronic lung disease, diabetes, heart disease, or stroke, or they had no scores of 4 or higher in the EURO-D depression scale [34, 35]. Absence of disability. The respondents reported no limitation in basic activities of daily living (ADL): walking indoors, dressing, bathing or showering, eating, getting into or out of bed, toileting.

A high level of cognitive function was considered to be an above-average total score on all tests of mental orientation, memory, and mathematical calculations (maximum score, 29 points): correctly state the day of the week, date, month, and year (1 point for each); remember list of 10 words, immediate and delayed recall (1 point for each); complete 5 consecutive mathematical calculations (subtractions, 1 point per answer). High level of physical function was recorded if the person had difficulty with no more than one of the following six activities: climb a full flight of stairs, climb several flights of stairs, lift more than 5 kg, lean / squat / kneel, push large objects, walk 100 meters.

Social engagement included paid work or volunteering in the previous month or caring for grandchildren at some time during the past 12 months. Social support was defined as living with a partner, providing economic or household help to relatives, friends, or neighbours, or engaging in a sport in the previous month.

The AHA-BPS model also assesses three dimensions, each using two indicators. The WHO definition includes physical, mental, and social well-being dimensions, operationalized as follows:

Physical well-being. The two indicators were non-frail or pre-frail according to the SHARE-FI scale [36] and good cognitive function, defined as meeting the orientation criterion (AHA-B, above) and being above the 10^th percentile (p10), age-adjusted (age groups: 50–64, 65–74, 75–84, and 85 years and older) in at least 3 of 4 cognitive tests (immediate memory, delayed memory, mathematical calculation, verbal flow).

Mental well-being. The two indicators were self-reported satisfaction with life (defined as 7 or higher on a 0–10 scale) and no depressive symptoms (defined as having 3 or fewer symptoms on the Euro-D scale) [34].

Social well-being. The two indicators were social participation, defined as any paid work, caring for grandchildren, and social activities (sports, training, religion, politics, volunteering) and a satisfaction score of 7 or higher on a 0–10 scale in the social activity performed and social support, including social network (i.e., having given or received financial or household help) and family support. For people with children or a partner, family support was defined as living with a partner or child or living within 5km of a son or daughter and a score <5 (never or seldom feeling alone) on the Revised University of California-Los Angeles (R-UCLA) Loneliness Scale [37]. For those without a partner or children, only the subjective criterion (R-UCLA <5) was measured.

The variables drawn from the SHARE database are shown in Supplementary S2 Table (S2 Table. Coding of dependent and independent variables selected from the SHARE database).