Association between metabolic syndrome and risk of both prevalent and incident frailty in older adults: Findings from The Irish Longitudinal Study on Ageing (TILDA)

Abstract

Objectives: Metabolic syndrome (MetS) is a risk factor for cardiovascular disease, diabetes, and all-cause mortality. Frailty is a condition of decreased multi-system physiological reserve where one has increased vulnerability to stressors. This study aimed to examine if MetS is associated with prevalent and incident frailty over a 4-year follow-up period in an aged population.

Methods: This study used data from waves 1 (2009-2011) and 3 (2014-2015) of The Irish Longitudinal Study on Ageing. Those aged <50 years or without baseline health assessment data were excluded. Baseline MetS status was determined using the National Cholesterol Education Program Third Adult Treatment Panel criteria. Frailty status was identified at both waves, operationalised using Fried's frailty phenotype (FP) and Rockwood's frailty index (FI). Ordinal logistic regression examined the cross-sectional association between MetS and prevalent frailty status. Those with prevalent pre-frailty or frailty were excluded and ordinal logistic regression models examined the association between MetS and incident frailty. Lastly, MetS' longitudinal associations with the five individual components of Fried's FP were examined. Models were adjusted for age, sex, education, smoking, chronic disease history and renal function.

Results: Ordinal logistic regression models (n > 5100), showed MetS was associated with prevalent frailty as assessed by both FP (odds ratio (OR) 1.29, p < 0.001) and FI (OR 1.65, p < 0.001). Of those who were non-frail at baseline, 2247 participants had longitudinal FP data, while 3546 participants had longitudinal FI data. Models demonstrated that MetS was associated with an increased likelihood of incident frailty for both FP (OR 1.57, p < 0.001) and FI (OR 1.29, p = 0.014). MetS was found to be associated with incident low physical activity (OR 1.57, p = 0.001) and incident unintentional weight loss (OR 1.59, p = 0.025).

Conclusions: MetS in those ≥50 years was found to be associated with an increased likelihood of incident frailty over a 4-year period, by 57 % when measured by FP and 29 % by FI. MetS should be considered a risk factor for frailty and be taken into considered in any comprehensive geriatric assessment given frailty's dynamic nature and MetS being potentially modifiable.

Keywords: Frailty; Insulin resistance; Metabolic syndrome; Obesity; Pre-frailty.