Original title: Vena cava filters in unstable elderly patients with acute pulmonary embolism Reference: Stein PD et al. Am J Med. 2014 Mar;127(3):222-5.
Filters in inferior vena cava may reduce mortality in patients with severe pulmonary embolism (PE) who are hemodynamically unstable. This has not been demonstrated in elderly patients, a growing demographic group where the risk-benefit analysis balance of each intervention is more delicate. Researchers at the University of Michigan retrospectively analyzed data from a large national health record, the Nationwide Inpatient Sample, and identified more than 2,000,000 patients >21 years who had been interned in the decade from 1999 to 2008 with a diagnosis of lung embolism. Of these, 71,305 patients (3.4% of the total) who had unstable symptoms, defined as shock or need for mechanical ventilation were selected. In-hospital all-cause mortality associated with the use or non-use of inferior vena cava filter in both thrombolyzed patients (n = 21,095) and not thrombolyzed (n = 50,210), stratified by age, were analyzed. The results are shown in Tables 1 and 2 (for the purpose of simplifying the figures, we excluded confidence intervals except in totals).
Table 1
|
Unstable patients with PE who receive thrombolytic therapy |
|||||
|
Age (years) |
Mortality using IVC filter (%) |
Mortality w/o IVC filter (%) |
Relative risk
|
Absolute risk reduction (%) |
NNH |
|
21-30 |
4,5 |
10,5 |
0,43 |
5,9 |
17 |
|
31-40 |
5,7 |
11,6 |
0,49 |
5,9 |
17 |
|
41-50 |
6,5 |
13,4 |
0,49 |
6,9 |
14 |
|
51-60 |
6,9 |
13,6 |
0,51 |
6,7 |
15 |
|
61-70 |
7,0 |
21,9 |
0,32 |
14,9 |
7 |
|
71-80 |
10,4 |
23,2 |
0,45 |
12,8 |
8 |
|
>80 |
10,4 |
29,7 |
0,35 |
19,3 |
5 |
|
Total (IC 95%) |
7,6 |
17,7 |
0,43 (0,39-0,47) |
10,0 (9,0-11,0) |
10 (9-11) |
Table 2
|
Unstable patients with PE who not receive thrombolytic therapy |
|||||
|
Age (years) |
Mortality using IVC filter (%) |
Mortality w/o IVC filter (%) |
Relative risk
|
Absolute risk reduction (%) |
NNH (CI 95%) |
|
21-30 |
16,7 |
30,0 |
0,56 |
13,3 |
8 |
|
31-40 |
20,6 |
39,9 |
0,52 |
19,3 |
5 |
|
41-50 |
25,7 |
43,3 |
0,59 |
17,6 |
6 |
|
51-60 |
30,1 |
45,9 |
0,66 |
15,8 |
6 |
|
61-70 |
35,2 |
51,2 |
0,69 |
16 |
6 |
|
71-80 |
37,1 |
56,6 |
0,65 |
19,6 |
5 |
|
>80 |
36,2 |
64 |
0,57 |
27,7 |
4 |
|
Total (IC 95%) |
33,3 |
51,8 |
0,64 (0,63-0,66) |
18,5 (18,0-19,0) |
5 (5-6) |
Figures show a reduction roughly half of in-hospital all-cause mortality with the use of inferior vena cava filter with a benefit that seems to be slightly higher in patients thrombolyzed. Unstable patients with PE who received thrombolytic therapy had a lower mortality than those who did not. Given the high mortality of these patients and a large absolute reduction in fatal events associated with the use of the filter, the number needed to treat (NNH) to save one life with this therapy is very low. Elderly patients (over 80 years) seems to get as much or more benefit from this intervention than younger subjects, with reduction figures of absolute risk and number needed to treat, below average across the age range.
Comment:
Despite the limitations inherent in a study grounded in administrative databases, with numerous potential puzzling variables that make it impossible the precise adjustment, all the results appear to be relevant. Moreover, it is highly unlikely that a similar controlled clinical trial in this population can be performed, since patients with PE hemodynamically unstable are uncommon (between 3.4 and 4.5% of the total), and it would take several centers to include having enough power to demonstrate differences in mortality, with an unacceptable cost. Although in elderly patients with unstable PE using vena cava filter is more or less similar to that of younger patients (29.9% versus 26.5%), this method is still used in less than one in three subjects, which in the light of the present work impresses that underutilization of therapy appears to be effective. Thrombolytic therapy, in turn, is associated with a reduction in mortality in this high-risk population, but is underutilized (in our experience in the Coronary Care Unit of the Hospital de Clinicas in Buenos Aires, we have seen patients who survived after an infusion of thrombolytics, despite experiencing a very severe PE with cardiogenic shock and not registrable TA). In conclusion, the use of inferior vena cava filters in patients hemodynamically unstable appears to reduce hospital mortality, regardless of age.
Courtesy by Dr. Alejandro Lakowsky. MTSAC
Dr. Alejandro Lakowsky
