Impact of social vulnerability on frailty transition among older adults in China: a national two-year cohort study

Background: Frailty in older adults has become a major concern. It is influenced by biological, social, psychological, and environmental factors, with social frailty playing a particularly significant role. The relationship between social frailty and health outcomes can accelerate frailty transitions, offering new insights into strategies to improve health in older adults. Methods: We obtained the data from the Fourth Sample Survey of the Aged Population in Urban and Rural China, with 2017 as the baseline and 2019 as the follow-up. We used the frailty index (FI) to assess physiological frailty and the social vulnerability index (SVI) to assess social frailty. We used logistic regression to analyse the impact of SVI on frailty transitions. Results: The analysis included 9093 older individuals, with an average age of 71.2 (standard deviation = 7.0) years, comprising 4495 women and 4598 men. Of these, 39.3% were robust, 45.1% were prefrail, and 15.6% were frail. Both the FI and SVI increased with age, and women showed higher frailty levels. Over the two years, 56.2% maintained stable frailty status, 14.2% improved, and 29.6% deteriorated. Correlation analysis revealed a moderate relationship between FI and SVI (r = 0.337; P < 0.001). Logistic regression analysis indicated that higher social frailty was associated with an increased risk of worsening frailty in non-frail (odds ratio (OR) = 1.017; P < 0.05) and prefrail individuals (OR = 1.021; P < 0.05), but had no effect on those who were already frail. Conclusions: Frailty deterioration with age is more common than improvement. Increased social frailty is a significant risk factor for the worsening of frailty, particularly in non-frail and prefrail individuals. Early identification and prevention of social frailty may help delay its progression.