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The Reply

      To the Editor:
      The likelihood of performing a randomized controlled trial of unstable patients with pulmonary embolism, particularly elderly patients, in whom vena cava filters appear to reduce mortality,
      • Stein P.D.
      • Matta F.
      Vena cava filters in unstable elderly patients with acute pulmonary embolism.
      is remote. Assuming 3.4%-4.5% of patients with pulmonary embolism are unstable,
      • Stein P.D.
      • Matta F.
      • Keyes D.C.
      • et al.
      Impact of vena cava filters on in-hospital case fatality rate from pulmonary embolism.
      • Kucher N.
      • Rossi E.
      • De Rosa M.
      • Goldhaber S.Z.
      Massive pulmonary embolism.
      59% are aged >60 years,
      • Stein P.D.
      • Matta F.
      Treatment of unstable pulmonary embolism in elderly and those with comorbid conditions.
      and 33% would consent, it would be necessary to screen 22,500 patients with pulmonary embolism to recruit 100 elderly unstable patients in each arm. Support for such a large randomized controlled trial is not readily obtained. Death in unstable patients with pulmonary embolism occurred on the day of admission or day 1 in 39%-47% and within 2 days of admission in 50%-61%.
      • Stein P.D.
      • Matta F.
      Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
      Recruitment and filter insertion would be unlikely in such patients, so we would still be left with selection bias, as defined by Girard et al.
      We evaluated unstable patients with a primary diagnosis of pulmonary embolism who did not have any of the comorbid conditions listed in the Charlson Index.
      • Stein P.D.
      • Matta F.
      Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
      • Charlson M.E.
      • Pompei P.
      • Ales K.L.
      • MacKenzie C.R.
      A new method of classifying prognostic comorbidity in longitudinal studies: development and validation.
      Among such patients who received thrombolytic therapy (74% without filters), death from pulmonary embolism was 8.4%, versus 2.7% with a filter.
      • Stein P.D.
      • Matta F.
      Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
      Among such patients who did not receive thrombolytic therapy (77% without filters), death from pulmonary embolism was 42%, versus 27% with a filter.
      • Stein P.D.
      • Matta F.
      Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
      In order to respond more completely to Girard et al, we further analyzed the data from this investigation. Among unstable patients with a primary diagnosis of pulmonary embolism who had none of the comorbid conditions listed in the Charlson Index, death attributable to pulmonary embolism among those who received thrombolytic therapy was 730 of 7070 (10%) without a vena cava filter, compared with 80 of 2640 (3.0%) with a filter (P <.0001) (unpublished data from Stein and Matta).
      • Stein P.D.
      • Matta F.
      Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
      Among such patients who did not receive thrombolytic therapy, death attributable to pulmonary embolism was 830 of 1740 (48%) without a vena cava filter, compared with 170 of 680 (25%) with a filter (P <.0001).
      In conclusion, unstable patients with a primary diagnosis of pulmonary embolism and no comorbid conditions showed fewer deaths attributable to pulmonary embolism with vena cava filters, just as all unstable patients with pulmonary embolism showed a lower all-cause case fatality rate with vena cava filters.

      References

        • Stein P.D.
        • Matta F.
        Vena cava filters in unstable elderly patients with acute pulmonary embolism.
        Am J Med. 2014; 127: 222-225
        • Stein P.D.
        • Matta F.
        • Keyes D.C.
        • et al.
        Impact of vena cava filters on in-hospital case fatality rate from pulmonary embolism.
        Am J Med. 2012; 125: 478-484
        • Kucher N.
        • Rossi E.
        • De Rosa M.
        • Goldhaber S.Z.
        Massive pulmonary embolism.
        Circulation. 2006; 113: 577-582
        • Stein P.D.
        • Matta F.
        Treatment of unstable pulmonary embolism in elderly and those with comorbid conditions.
        Am J Med. 2013; 126: 304-310
        • Stein P.D.
        • Matta F.
        Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused.
        Am J Med. 2012; 125: 465-470
        • Charlson M.E.
        • Pompei P.
        • Ales K.L.
        • MacKenzie C.R.
        A new method of classifying prognostic comorbidity in longitudinal studies: development and validation.
        J Chronic Dis. 1987; 40: 373-383

      Linked Article

      • The Pseudo-effect of Vena Cava Filters
        The American Journal of MedicineVol. 127Issue 7
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          Stein and Matta1 describe another strong (P < .001) statistical association between inferior vena cava filter placement and lower in-hospital all-cause mortality in unstable patients with pulmonary embolism. As in their previous studies that explored the same database,2,3 the authors conclude that filters may be underused, and even calculate that only 5 patients would need to receive a filter to save one life in patients aged >80 years.1 We believe that the quality of the available evidence is insufficient to support such interpretations.
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