Frailty is a multidimensional concept of vulnerability closely associated with ageing and adverse health outcomes, including mortality, chronic diseases and functional impairments. Despite its clinical relevance, the conceptualisation of frailty remains challenging, highlighting the need to explore how it relates to general health decline over time.

To evaluate whether a Frailty Index is associated with subsequent decline in self-rated health (SRH) over 13 months in older adults.

Longitudinal cohort design.

A total of 660 community dwelling participants aged 65 and older from Canton Ticino, Southern Switzerland, were included. The follow-up period, conducted as part of the Corona Immunitas study, spanned from September 2020 to November 2021.

The Rockwood Frailty Index categorised participants into frail, prefrail and robust groups based on 30 variables across seven domains. SRH trajectories were analysed over time using linear mixed-effects models, adjusting for socio-demographic and health-related covariates.

From 660 participants, 41.5% were robust, 48.2% prefrail and 10.3% frail at baseline, with baseline mean SRH 4.22, 3.74 and 2.97, respectively. SRH declined over 13 months in all groups (β=–0.009, p

Frail individuals experience a more pronounced decline in SRH compared with robust and prefrail individuals, highlighting their heightened vulnerability. The Rockwood Frailty Index was associated with health deterioration over time and clearly distinguished between frailty states, supporting its use to identify older adults at higher risk of subsequent health decline and to inform early detection and prevention strategies in older populations.