Frailty index predicts poor outcome in COVID-19 patients

Frailty is a condition of increased vulnerability to endogenous and exogenous stressors, resulting from the interaction of progressive age-related decline in physiologic systems with chronic diseases, leading to decreased functional reserve capacities [1]. The effect of frailty on patient’s clinical outcomes has been examined in several settings of care, including intensive care units (ICU) and acute hospital wards [1, 2], showing to be a reliable predictor of clinical and health care related outcomes. Based on these and other evidences, some scientific societies (https://www.nice.org.uk/guidance/ng159/resources/critical-care-admission-algorithm-pdf-8708948893; https://www.brc-rea.be/wp-content/uploads/2020/03/Ethical-decision-making-in-emergencies_COVID19_22032020_final.pdf) are recommending to assess frailty in patients with coronavirus disease 19 (COVID-19) infection to guide their triage. However, not all international scientific associations have similar positions (https://smw.ch/article/doi/smw.2020.20229; http://www.siaarti.it/SiteAssets/News/COVID19%20-%20documenti%20SIAARTI/SIAARTI%20-%20Covid19%20-%20Raccomandazioni%20di%20etica%20clinica.pdf).

Therefore, we decided to evaluate the role of frailty assessment in patients with COVID-19. Here, we analyzed the data of a cohort of consecutive COVID-19 patients admitted to 8th floor of San Gerardo hospital between February 27th and April 7th, 2020. Inclusion criteria were age > 18 years, informed consent and hospitalization due to COVID-19 infection. There were no exclusion criteria. Frailty was assessed with the Frailty Index (FI), a commonly used tool which is based on the concept that frailty is the result of an accumulation of deficits during lifetime [3]. The FI evaluated coexisting diseases, cognitive and physical impairments and laboratory abnormalities. For each variable, we assigned a score 0 in the absence and 1 in the presence of a deficit. The score was calculated for each participant by dividing the sum of the deficits by the total number of variables measured. Overall, we assessed 43 variables, which provided our index with a sufficient amount of robustness [3]. Importantly, one study has shown that a FI constructed with a similar number of variables was superior to other frailty tools in predicting mortality [4]. The variables included in the 43-item FI are listed in the Electronic Supplementary Material along with the graphical distribution of the scores.

Among 105 patients included in our study, 40 had a “do not intubate” indication, 58 had an “intubate if needed” indication and 7 had neither. The FI median score was 0.17 [interquartile ranges, IQR 0.12, 0.26] among the 42 patients died or transferred to ICU and 0.07 [IQR 0.05, 0.14] among the 63 patients who recovered (p < 0.001) (Table 1). According to a previous study, participants with a FI score ≥ 0.25 were considered frails [5]. In a multivariable logistic model (see Electronic Supplementary Material), including age, sex and FI, age and the dichotomized FI were independent predictors of inhospital mortality or ICU admission (odds ratio in patients with FI ≥ 0.25 vs < 0.25 1.32, 95% confidence intervals: 1.03; 1.70).

Table 1 Baseline characteristics of patients by outcome (recovered or death/transferred to ICU)

We suggest integrating the frailty assessment in all the COVID-19 patients at hospital admission. With electronic medical records progressively more available in the hospitals, the assessment of frailty with an electronic FI can help clinicians in their decision-making processes, identifying patients most likely to require ICU admission and those with poor outcomes. Future studies are needed to determine if FI is superior to other tools in predicting the outcomes of COVID-19 patients.