Background Frailty is a geriatric syndrome closely linked to a variety of adverse health outcomes. Thus, it is important to identify factors associated with the development of frailty. It was the aim of this study to examine, if, and to what extent partner loss, a highly stressful life event, affects frailty trajectories of community dwelling adults aged 50 or older.

Methods Using six waves of panel data from the Survey of Health, Ageing and Retirement in Europe (SHARE), we investigated the effect of partner loss on frailty trajectories estimating growth curve models. Our sample included 183 502 observations of 83 494 community-dwelling individuals aged 50 or older from 21 European countries collected between 2004 and 2017. Frailty was measured using the validated sex-specific SHARE-Frailty-Instrument including muscular weakness, unintended weight loss, decrease in walking capacity, low physical activity and exhaustion.

Results Our sample contained 79 874 participants who lived in a partnership during their entire observational period and 3620 participants who lost their partner during their observational period. Both men (β=0.184 (95% CI: −0.017 to 0.386), p=0.073) and women (β=0.237 (95% CI: 0.106 to 0.369), p<0.001) showed initial effects of partner loss on frailty, but while only women gradually recovered over time (β=−0.023 (95% CI: −0.039 to −0.008), p=0.002), among men, the effect of partner loss persisted (β<0.001 (95% CI: −0.029 to 0.029), p=0.998).

Conclusion This study revealed that partner loss is followed by elevated frailty. However, while women’s frailty tended to recover from partner loss over time, men’s frailty remained elevated. Notable individual differences in the response of frailty trajectories to partner loss suggest the existence of effect modifiers.