Association of Serum Creatinine-Cystatin C Ratio With Hospital-Associated Complications and Post-Discharge Mortality.

Aim: To examine the associations of serum creatinine-cystatin C ratio (CCR) at admission with mortality at 3 months post-discharge and the incidence of hospital-associated complications (HAC).

Methods: The study was conducted at 2 centers and included patients admitted to and discharged from geriatric wards between October 2019 and July 2023. Patient backgrounds were compared according to mortality at 3 months post-discharge. Next, logistic regression analysis was performed using mortality at 3 months post-discharge as the objective variable. Similarly, logistic regression analysis was performed with the incidence of HAC as the objective variable.

Results: Two hundred thirty-one patients were included in the analysis. The death group had significantly lower CCR (p < 0.001). In logistic regression analysis adjusted for age and sex, a low CCR was associated with increased mortality (odds ratio 3.260, p = 0.003). This association remained significant even after additional adjustment for kidney function (odds ratio 2.710, p = 0.014). The lowest CCR quartile showed a similar trend with an increased risk of death at 3 months compared to the highest quartile, even after extensive adjustment for demographics, kidney function, comorbidities, frailty, and cognitive function (Odds Ratio 4.157, p = 0.086). On the other hand, no significant association was found between CCR and the incidence of HAC.

Conclusions: A low CCR predicted higher post-discharge mortality after basic adjustment; although the association attenuated when frailty and cognition were included, a risk increase persisted for the lowest versus highest quartile. Measuring CCR in hospitalized older adults may be useful for early identification of patients at high risk of death.