Study Population And Factors At Resuscitation
The study included 1,285 patients, of which 1,073 (84%) were younger than 75 years and 212 (16%) 75 years or older (Table 1). OHCAs were less common among the elderly with an occurrence of 43% compared to 64% in the young group, p < 0.001 (Table 1). A number of other differences between the younger and the elderly population were noted: less elderly patients had an independent preadmission functional status (75% vs. 90%, p < 0.001), a non-shockable initial CA rhythm was more common (49% vs. 35%, p < 0.001), and ROSC was achieved faster among the elderly patients (median of 10 min vs. 16 min, p < 0.001).
Table 1
|
Age < 75 (n = 1073)
|
Age ≥75 (n = 212)
|
p
|
Women, % (no.)
|
281 (26)
|
70 (33)
|
0.041
|
Location of arrest, % (no.)
|
|
|
< 0.001
|
OHCA
|
64 (691)
|
43 (92)
|
|
IHCA
|
27 (286)
|
46 (97)
|
|
ICUCA
|
9 (96)
|
11 (23)
|
|
Women, % (no.)
|
281 (26)
|
70 (33)
|
0.041
|
Witnessed arrest, % (no.) 1
|
935 (87)
|
193 (91)
|
0.130
|
Initial cardiac-arrest rhythm, % (no.)
|
|
|
< 0.001
|
Shockable (VT or VF)
|
641 (60)
|
94 (44)
|
|
Non-Shockable (all other
rhythms)
|
378 (35)
|
104 (49)
|
|
Unknown
|
54 (5)
|
14 (6.6)
|
|
Time to ROSC in minutes, median (IQR) 2
|
16 (10–23)
|
10 (5–18)
|
< 0.001
|
Independent preadmission functional status % (no.)3
|
90 (960)
|
75 (158)
|
< 0.001
|
1 2% of patients are missing this information |
2 9,5% of patients are missing this information |
3 4.7% of patients are missing this information |
Treatment Intensity & ICU Factors
No difference was observed in the APACHE II scores between the elderly and younger patients when points for age where excluded (Table 2). Treatment intensity was lower in the elderly than in the younger age group, with median daily average TISS scores of 34 and 37 for the elderly and younger patients, respectively, p < 0.001. The total amount of TISS points was also lower for the elderly (116 vs. 147, p < 0.001) (Table 2). In-hospital as well as in-ICU mortality was higher for the elderly group (ICU mortality 33% vs. 18%, p < 0.001; hospital mortality 49% vs. 33%, p < 0.001). The ICU LOS was shorter for the elderly than for the younger patients (Table 2). The ICU LOS among the survivors was however not different. Table 2 details the ICU factors, in-hospital mortality, TISS-point distribution and the difference in the selected treatments received at the hospital. TISS-point distribution can be viewed in more detail in the supplementary material (Additional file 1–3).
Table 2
Intensive care unit-factors
|
Age < 75 (n = 1073)
|
Age ≥75 (n = 212)
|
p
|
APACHE II-score excluding age points, median (IQR)
|
20 (15–27)
|
22 (15–27)
|
0.181
|
TISS-Score, median (IQR)
|
|
|
|
Daily average
|
37 (31–43)
|
34 (28–41)
|
< 0.001
|
Total TISS-score
|
147 (93–227)
|
116 (65–192)
|
< 0.001
|
Treatments received, no. (%)
|
|
|
|
Controlled ventilation with or
without PEEP
|
1055 (98)
|
197 (93)
|
< 0.001
|
Induced hypothermia
|
450 (42)
|
34 (16)
|
< 0.001
|
Vasoactive drug infusion (> 1 drug)
|
503 (47)
|
80 (38)
|
0.015
|
Continous antiarrhythmia infusions
|
212 (20)
|
35 (17)
|
0.273
|
Rx of seizures
|
140 (13)
|
13 (6)
|
0.004
|
Hemodialysis in unstable patient
|
18 (2)
|
8 (4)
|
0.048
|
Arterial line
|
1071 (100)
|
211 (100)
|
0.432
|
In-hospital mortality %(no.)
|
|
|
|
Dead in ICU
|
18 (194)
|
33 (69)
|
< 0.001
|
Dead in hospital
|
33 (357)
|
49(104)
|
< 0.001
|
Length of stay in days, median (IQR)
|
|
|
|
ICU
|
3 (2–5)
|
2 (1–4)
|
< 0.001
|
Hospital
|
10 (4–20)
|
8 (3–16)
|
0.003
|
Length of stay in days among patients discharged alive, median (IQR)
|
|
|
|
ICU
|
3 (2–6)
|
3 (2–6)
|
0.085
|
Hospital
|
14 (8–24)
|
14 (8–23)
|
0.654
|
Neurological Outcome And Mortality
Neurological outcome was worse for the elderly group, with only 24% (50/212 patients) having CPC scores of 1–2 after 12 months, compared with 47% (507/1073 patients) of the younger age group, p < 0.001. Long-term mortality was higher for the elderly group compared to the younger group; 70% of the elderly (vs. 44%) had died within two years, p < 0.001. Mortality in the elderly versus the younger age group during the first year is shown in Fig. 2. Separate Kaplan Meier curves illustrating mortality during the whole follow-up period for all patients, patients based on location of arrest (OHCA, IHCA and ICUCA) as well as based on initial rhythm (shockable and non-shockable) can be found in the supplementary material (Additional file 5–6). The median follow-up time was 1.6 years per patient.
Factors independently associated with unfavourable neurological outcome was age above 75 years (OR = 3.27, 95% CI: 2.12–5.03, p < 0.001), dependent pre-admission functional status (OR = 3.13, 95% CI: 1.69–5.79, p < 0.001), non-shockable initial CA rhythm (OR shockable rhythm = 0.43, 95% CI: 0.30–0.60, p < 0.001), time to ROSC in 10 minutes (OR = 1.61, 95% CI: 1.34–1.93, p < 0.001) and APACHE II score excluding points for age (OR = 1.96, 95% CI: 1.61–2.39, p < 0.001).
Factors independently associated with mortality were age above 75 years (OR = 3.36, 95% CI: 2.21–5.11, p < 0.001), dependent pre-admission functional status (OR = 2.96, 95% CI: 1.60–5.50, p < 0.001), initial CA rhythm (OR shockable rhythm = 0.56, 95% CI: 0.40–0.77, p < 0.001), location of CA (ICUCA OR = 2.27, 95% CI: 1.26–4.08, p = 0.006), time to ROSC (OR = 1.36, 95% CI: 1.16–1.60, p < 0.001) and APACHE II score excluding age (OR = 2.06, 95% CI: 1.70–2.50, p < 0.001). Table 4 details the independent predictors of an unfavourable neurological outcome and Table 5 the independent predictors of mortality.
Table 4
Univariate models and multivariate models for risk factors predicting 12-month unfavourable cerebral performance status
|
Univariate model
|
Multivariate model
|
Variable
|
OR (95% CI)
|
p
|
OR (95% CI)
|
p
|
Age
|
|
|
|
|
Young (< 75y)
|
1
|
|
1
|
|
Elderly ( > = 75)
|
3.09 (2.19–4.36)
|
< 0.001
|
3.27 (2.12–5.03)
|
< 0.001
|
Pre-admission functional status
|
|
|
|
|
Independent
|
1
|
|
1
|
|
Dependent
|
4.07 (2.48–6.67)
|
< 0.001
|
3.13 (1.69–5.79)
|
< 0.001
|
Initial CA-rhythm
|
|
|
|
|
Non-shockable
|
1
|
|
1
|
|
Shockable
|
0.32 (0.25–0.41)
|
< 0.001
|
0.43 (0.30–0.60)
|
< 0.001
|
Location of arrest
|
|
|
|
|
OHCA
|
1
|
|
1
|
|
IHCA
|
1.78 (1.37–2.30)
|
< 0.001
|
1.46 (0.98–2.18))
|
0.065
|
ICUCA
|
2.24 (1.47–3.41)
|
< 0.001
|
2.24(1.21–4.16)
|
0.010
|
Witnessed arrest (not witnessed = 1)
|
0.47 (0.31–0.70)
|
< 0.001
|
0.70(0.43–1.12)
|
0.134
|
Time to ROSC in 10 minutes
|
1.15 (1.02–1.29)
|
0.020
|
1.61 (1.34–1.93)
|
< 0.001
|
APACHE II-score excluding age points1
|
2.51 (2.13–2.95)
|
< 0.001
|
1.96 (1.61–2.39)
|
< 0.001
|
A total of 980 patients were included. 94 patients had missing CPC, 60 patients had missing functional status, 68 patients had missing initial rhythm, 24 patients had missing if the arrest was witnessed, 118 patients had missing time to ROSC, 1 patient had missing APACHE II-score.
|
1 Each step increases the variable by 10 |
Table 5
Univariate models and multivariate models for risk factors predicting 12-month mortality.
|
Univariate model
|
Multivariate model
|
Variable
|
OR (95% CI)
|
p
|
OR (95% CI)
|
p
|
Age
|
|
|
|
|
Young (< 75y)
|
1
|
|
1
|
|
Elderly ( > = 75)
|
3.44 (2.44–4.84)
|
< 0.001
|
3.36 (2.21–5.11)
|
< 0.001
|
Pre-admission functional status
|
|
|
|
|
Independent
|
1
|
|
1
|
|
Dependent
|
4.20 (2.55–6.92)
|
< 0.001
|
2.96 (1.60–5.50)
|
< 0.001
|
Initial CA-rhythm
|
|
|
|
|
Non-shockable
|
1
|
|
1
|
|
Shockable
|
0.33 (0.26–0.42)
|
< 0.001
|
0.56 (0.40–0.77)
|
< 0.001
|
Location of arrest
|
|
|
|
|
OHCA
|
1
|
|
1
|
|
IHCA
|
2.07 (1.61–2.67)
|
< 0.001
|
1.61 (1.11–2.34)
|
0.12
|
ICUCA
|
2.29 (1.52–3.449
|
< 0.001
|
2.27 (1.26–4.08)
|
0.006
|
Witnessed arrest (not witnessed = 1)
|
0.59 (0.40–0.86)
|
< 0.006
|
0.80 (0.51–1.27)
|
0.353
|
Time to ROSC in 10 minutes
|
1.04 (0.93–1.16)
|
0.520
|
1.36 (1.16–1.60)
|
< 0.001
|
APACHE II-score excluding age points1
|
2.34 (2.01–2.73)
|
< 0.001
|
2.06 (1.70–2.50)
|
< 0.001
|
A total of 1055 patients were included. 60 patients had missing functional status, 68 patients had missing initial rhythm, 24 patients had missing if the arrest was witnessed, 118 patients had missing time to ROSC, 1 patient had missing APACHE II-score.
|