30-day mortality or longer follow-up?
The Kaplan Meier survival analysis of all cardiac surgery is shown in Figure 1. The survival curves of the cardiac surgery population and that of the general Dutch population run parallel to each other from approximately 120 days onwards. The mortality rate in the remainder of the first year is 0.065 (95% CI of 0.060 - 0.710) deaths per 1000 person-days and is comparable to the mortality rate in the age-matched general population of 0.06 deaths per 1000 person-days. The hazard function in Panel B seems to stabilize after the same period. Analyses using only cardiac mortality yielded similar results. Figure 1: Kaplan Meier survival curve with 95% confidence interval after cardiac surgery %
2.94 3.02 3.57 4.68 5.16 6.20
0.0015
N
972 998 1181 1549 1707 2052
30
60
90
120
180
365
Days after surgery
0.0000
90
92
0.0005
94
0.0010
Hazard
96
Survival (%)
98
In−hospital mortality 30−day mortality Operative mortality 120−day mortality 6−months mortality 1−year mortality
0.0020
B
100
A
30
60
90 120
180
365
Days after surgery
The green line represents the survival rate of the age-matched general population in The Netherlands. The survival rate of the cardiac surgery population equals that of the general population from approximately 120 days after surgery onwards. The hazard (risk of mortality) after cardiac continues to decline well after 30 days postoperatively. The constant phase of the hazard seems to start after approximately 120 days. Table 2: Comparison of in-hospital and 30-day mortality 30-day mortality
In-hospital mortality
No
Yes
No
31913 (94.6 %)
209 (0.6 %)
32122 (97.1 %)
Yes
183 (0.6 %)
789 (2.4 %)
972 (2.9 %)
32096 (97.0 %)
998 (3.0 %)
33094 (100 %)
Figures in bold indicate the number of deaths that are included in 30-day mortality, but not in inhospital mortality and the other way around.
77