Table 2 Epidemiology, clinical presentation, initial analytical and radiological assessment, and clinical outcomes in patients ≥ 65 years with confirmed COVID-19, according to Clinical Frailty Score

Epidemiological variables

 Age, years, median (IQR)

785

78 (71–84)

74 (69–79)

83 (79–88)

85 (81–90)

< 0.001

84 (80–88)

< 0.001

 Age group, n (%)

785

< 0.001

< 0.001

 65–74 years

301 (38.3)

256 (55.8)

32 (15.4)

13 (11.0)

45 (13.8)

 75–84 years

291 (37.1)

159 (34.6)

88 (42.3)

44 (37.3)

132 (40.5)

 85–100 years

291 (37.1)

44 (9.6)

88 (42.3)

44 (37.3)

149 (45.7)

 Female sex, n (%)

785

364 (46.4)

192 (41.8)

106 (51.0)

66 (55.9)

0.007

172 (52.8)

0.002

 First wave, n (%)

785

142 (18.1)

94 (20.5)

30 (14.4)

18 (15.3)

0.11

48 (14.7)

0.039

 Long-term care resident, n (%)

785

52 (6.6)

6 (1.3)

16 (7.7)

30 (25.4)

< 0.001

46 (14.1)

< 0.001

 CCI, median (IQR)

781

5 (4–7)

4 (3–5)

6 (5–9)

7 (6–9)

< 0.001

7 (5–8)

< 0.001

 Baseline CCI ≥ 5, n (%)

781

458 (58.8)

177 (38.6)

172 (83.5)

109 (94.0)

< 0.001

281 (86.1)

< 0.001

Clinical presentation

 Duration of symptoms (days), median (IQR)

743

6 (3–9)

7 (4–10)

5 (2–9)

3 (1–7)

< 0.001

4 (2–8)

< 0.001

 Duration of symptoms ≤ 5 days, n (%)

743

340 (45.6)

175 (38.8)

97 (50.0)

68 (67.3)

< 0001

165 (55.9)

< 0.001

 Fever, n (%)

778

387 (52.7)

280 (61.1)

93 (45.1)

52 (45.6)

< 0.001

145 (45.3)

< 0.001

 Dyspnea, n (%)

782

453(57.9)

263 (57.3)

127 (61.1)

63 (54.8)

0.50

190 (58.8)

0.49

 Dry cough, n (%)

777

371 (47.7)

249 (54.4)

89 (43.2)

33 (29.2)

< 0.001

122 (38.2)

< 0.001

 Asthenia, n (%)

771

361 (46.8)

234 (51.5)

87 (42.6)

40 (35.4)

0.003

127 (46.8)

0.002

 Diarrhea, n (%)

772

182 (23.6)

123 (27.0)

48 (23.4)

11 (9.8)

0.001

59 (18.6)

0.007

 Myalgia-arthralgia, n (%)

767

171 (22.3)

136 (29.9)

27 (13.4)

8 (7.3)

< 0.001

35 (11.2)

< 0.001

 Wet cough, n (%)

777

133 (17.1)

78 (17.0)

34 (16.5)

21 (18.6)

0.79

55 (17.2)

0.92

 Confusion, n (%)

779

100 (12.8)

35 (7.6)

32 (16.7)

33 (29.2)

< 0.001

65 (20.3)

< 0.001

 Anosmia-dysgeusia, n (%)

762

78 (10.2)

64 (14.2)

12 (6.0)

2 (1.8)

< 0.001

14 (4.5)

< 0.001

Analytical and radiological parameters on admission

 Oximetry < 94% at room temperature, n (%)

735

349 (47.3)

209 (47.9)

89 (46.1)

50 (47.2)

0.82

139 (47.3)

0.66

 Lymphocytes < 1.0 × 10³/L, n (%)

785

451 (57.5)

260 (56.6)

121 (58.2)

70 (59.3)

0.85

191 (58.9)

0.92

 C-reactive protein > 10 mg/dL, n (%)

782

284 (36.3)

173 (37.8)

69 (33.3)

42 (35.9)

0.215

111 (34.3)

0.31

 Procalcitonin > 0.5 ng/mL, n (%)

733

106 (14.5)

48 (11.2)

31 16.3)

27 (23.9)

0.002

58 (19.1)

0.002

 Ferritin > 500 mg/L, n (%)

725

412 (56.8)

270 (63.2)

92 (46.7)

50 (49.5)

< 0.001

142 (47.7)

< 0.001

 Lactate dehydrogenase > 250 U/L, n (%)

735

487 (66.3)

305 (70.6)

118 (60.8)

64 (58.7)

0.011

182 (60.1)

0.003

 D-dimers > 1 mg/mL, n (%)

735

357 (51.4)

171 (39.6)

103 (52.3)

83 (78.3)

< 0.001

186 (61.4)

< 0.001

 Interleukin 6 > 10 pg/mL, n (%)

587

471 (80.2)

279 (79.1)

131 (83.4)

61 (76.3)

0.39

192 (81.0)

0.92

 Brain natriuretic peptide > 125 pg/mL, n (%)

722

591 (81.9)

309 (73.5)

175 (91.5)

108 (96.4)

< 0.001

283 (93.4)

< 0.001

 Potassium < 3.5 mmol/L, n (%)

639

78 (12.2)

51 (14.0)

20 (11.3)

7 (7.1)

0.053

27 (9.8)

0.11

 eGFR < 60 ml/min/m², n (%)

781

375 (48.0)

171 (37.5)

125 (60.1)

79 (67.5)

< 0.001

204 (62.8)

< 0.001

 Troponin T > 14 ng/L, n (%)

731

489 (66.9)

225 (52.4)

160 (83.3)

104 (94.5)

< 0.001

264 (87.4)

< 0.001

 Opacities > 50% of lung surface on X-rays, n (%)

785

196 (25.0)

121 (26.4)

54 (26.0)

21 (17.8)

0.13

75 (23.0)

0.20

Clinical outcomes

 In-hospital mortality, n (%)

785

178 (22.7)

58 (12.6)

57 (27.4)

63 (53.4)

< 0.001

120 (36.6)

< 0.001

 Readmission, n (%)

785

55 (7.2)

21 (4.8)

25 (12.1)

9 (8.0)

0.003

34 (10.7)

0.002

 Intensive care unit admission, n (%)

784

114 (14.4)

99 (21.6)

14 (6.7)

1 (0.9)

< 0.001

15 (4.6)

< 0.001

 Invasive mechanical ventilation, n (%)

781

78 (10.0)

67 (14.8)

11 (5.3)

0 (0.0)

< 0.001

11 (3.4)

< 0.001

 Length of hospital stay (days), median (IQR)

774

10 (6–16)

9 (6–15)

10 (6–18)

11 (7–15)

0.36

10 (6–17)

0.16

 Length of hospital stay < 10 days, n (%)

774

372 (48.1)

228 (50.4)

94 (45.2)

50 (43.9)

0.28

144 (44.7)

0.12