Social vulnerability as a predictor of mortality and disability: cross-country differences in the survey of health, aging, and retirement in Europe (SHARE).

Background: Social factors are important for health; the concept of social vulnerability considers them holistically and can be quantified using a social vulnerability index (SVI).

Aims: Investigate the SVI in relation to mortality and disability, independent of frailty, in middle-aged and older European adults, and examine how this relationship differs across countries.

Methods: 18,289 community-dwelling participants 50 years and older from SHARE wave 1 (2004) were included in our sample. A 32-item SVI and a 57-item frailty index were calculated for individuals as the proportion of deficits present out of the total number considered. Countries were grouped based on their social model: Nordic (Denmark, Netherlands, Sweden), Continental (France, Austria, Belgium, Germany) and Mediterranean (Greece, Italy, Spain). Outcome measures were 5-year mortality and disability (≥1 dependency with activities of daily living) at wave 4 (2011-2012).

Results: High social vulnerability (highest quartile) predicted mortality (HR = 1.25, 95 % CI 1.07-1.45), and disability (OR = 1.36, 95 % CI 1.15-1.62) after controlling for age, sex, baseline disability and frailty level. When analyses were split by social model, social vulnerability remained a significant predictor of mortality for Continental (HR = 1.36, CI 1.05-1.77) and Mediterranean (HR = 1.33, CI 1.03-1.72) countries, but not the Nordic (HR = 1.02, CI 0.76-1.37) countries; the same pattern was observed for disability (Nordic OR = 1.06, CI 0.72-1.55; Continental OR = 1.53, CI 1.20-1.96; Mediterranean OR = 1.58, CI 1.13-2.23).

Discussion/conclusions: Social vulnerability was a significant predictor of mortality and disability, though when controlling for frailty, this relationship varied by the social model of the country.