Association of Frailty With Mortality in Older Inpatients With Covid-19

A Cohort Study

Darren Aw; Lauren Woodrow; Giulia Ogliari; Rowan Harwood

Disclosures

Age Ageing. 2020;49(6):915-922. 

In This Article

Results

From 1 March 2020 to 30 April 2020, 982 patients aged 18 years and older were admitted and diagnosed with COVID-19. Among these, 305 patients were aged 18–64 years and 677 patients were aged 65 years and older (Supplementary Table S1). Patients aged 65 years and over were included in our study (Supplementary Figure S1, flow chart of study design). Table 1 shows the baseline characteristics of our study population, by gender. Among all patients aged 65 years and over, mean age was 81.1 years (SD 8.1), 311 (45.9%) were women, mean NEWS-2 score was 3.7 (SD 2.9) and 506 (74.7%) had a positive RT-PCR test. Ninety-seven (14.3%) were fit or well on the CFS, and 369 (54.5%) were moderately or severely frail. No difference in the proportion of those with positive RT-PCR test, radiological and clinical diagnosis of COVID-19 was observed between men and women (Table 1). Supplementary Figure S2 shows the distribution of NEWS-2 score.

Table 2 shows the characteristics of patients aged 65 years and older, across frailty categories. Mean age and mean NEWS-2 score were highest among those patients with CFS 7–9, compared to the other frailty categories (P < 0.001 and 0.035, respectively). There was a significantly higher number of patients with one or more hospital attendances in 2019 for higher CFS groups 6 and 7–9, compared with those in the lower groups (P < 0.001). The proportion of women did not differ across frailty categories.

The bivariate correlation between NEWS-2 score and CFS categories on admission was non-significant, with a two-tailed Spearman's rho coefficient of 0.071 (P = 0.067, n = 663 patients, Supplementary Figure S3).

During a mean follow-up of 34.3 days, 271 (40.8%) patients aged 65 years and older, with a known frailty score, died. For 234 of these 271 patients, death certificates were available; 216 patients were certified as dying from COVID-19. We could not retrieve the death certificate for 37 patients who died following discharge.

Supplementary Table S2 shows the distribution of diagnostic criteria for COVID-19, by survival status.

Table 3 shows the univariate, unadjusted association between frailty, demographic and clinical variables and all-cause mortality, among 664 patients aged 65 years and older with known frailty category. Older age, male sex and higher NEWS-2 score were associated with increased risk of all-cause mortality (all P < 0.001). In contrast, ethnicity, IMD quintile and previous admissions in 2019 were not associated with mortality.

Figure 1 illustrates the association between frailty and all-cause mortality, after full adjustment for covariates. During follow-up, the proportion of those who died was lowest among those with CFS 1–3 (26.8%) and highest among those with CFS 6 (50.2%) and CFS 7–9 (48.8%).

Figure 1.

All-cause mortality by frailty in patients aged 65 years and older. This figure presents the survival curves for 664 patients aged 65 years and older with known CFS category. The P value is for the association between CFS category and all-cause mortality, after full adjustment for age, sex, ethnicity, IMD quintile, NEWS-2 score on admission and previous admissions in 2019 (Cox regression). Number of patients in each CFS category: CFS 1–3, n = 97; CFS 4, n = 96; CFS 5, n = 101; CFS 6, n = 203; CFS 7–9, n = 166. Number of patients who died during follow-up in each CFS category: CFS 1–3, n = 26; CFS 4, n = 30; CFS 5, n = 31; CFS 6, n = 102; CFS 7–9, n = 81. One patient with CFS 4, who died during follow-up, was excluded from the analysis for missing NEWS 2 score on admission.

Table 4 shows the HRs and CIs for the association between frailty and all-cause mortality. In the whole cohort of 664 patients, higher frailty scores were associated with the increased risk of mortality (P = 0.004, after full adjustment). After adjustment for covariates, patients with CFS 4 and CFS 5 had non-significant 1.30-fold (95% CI 0.76–2.21) and 1.19-fold (95% CI 0.70–2.03) increased mortality risk, respectively, compared to those with CFS 1–3 (P = 0.338 and 0.530, respectively). In contrast, those with CFS 6 had a 2.13-fold (95% CI 1.34–3.38) and those with CFS 7–9 had a 1.79-fold (95% CI 1.12–2.88) increased mortality risk, respectively, compared to those with CFS 1–3 (P = 0.001 and 0.016, respectively).

After full adjustment, older age, male sex and higher admission NEWS-2 score were associated with increased risk of mortality (P = 0.002, P < 0.001 and P < 0.001, respectively), while ethnicity, IMD quintiles and previous hospital admissions in 2019 were not (Table 4).

A minority of patients aged 65 years and older was admitted to an intensive treatment unit (ITU) (n = 37, 5.6%). Among these, mean age was 71.8 years (SD 5.4), 16 (43.2%) were women and mean admission NEWS-2 score was 5.2 (SD 3.5); 21 (56.8%) had CFS 1–3, 13 (35.1%) had CFS 4 and 3 (8.1%) had CFS 6 (Supplementary Table S5). Of these patients, 15 (40.5%) died during follow-up; in all cases, death was due to COVID-19. In comparison, those that were not admitted to ITU were frailer, older, and more had a hospital admission in 2019.

In sensitivity analyses, the association between frailty and mortality was similar when cases were confined to RT-PCR positive cases (Supplementary Figure S4 and Supplementary Table S2) and those in whom death was attributed to COVID-19 (Supplementary Table S3 and Supplementary Table S4).

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