Importance of Early Insertion of Inferior Vena Cava Filters in Unstable Patients with Acute Pulmonary Embolism.
Am J Med. 2018 Jun 12;:
Authors: Stein PD, Matta F, Lawrence FR, Hughes MJ
BACKGROUND: Immortal time bias is a possible confounding factor in cohort studies. In this investigation, we assessed mortality with inferior vena cava (IVC) filters in unstable patients with pulmonary embolism using a design that eliminated immortal time bias.
METHODS: Data are from Premier Healthcare Database, 2010-2014. International Classification of Disease-9th Clinical Modification codes were used. Unstable patients with pulmonary embolism and an admitting diagnosis of pulmonary embolism as well as a primary diagnosis of pulmonary embolism were included. A time dependent analysis was used according to the day of IVC filter insertion.
RESULTS: Among all patients, irrespective of the use of thrombolytic therapy, in-hospital all- cause mortality in those who received an IVC filter was 35 of 180 (19.4%) versus 122 of 299 (40.8%) with no filter (P<0.0001). Mortality was lower in patients in whom the IVC filter was inserted on days 1 or 2, (21.4% versus 40.8%, P=0.017, and 14.8% versus with 29.2%, P= 0.023), but it was not lower in those in whom the filter was inserted on subsequent days.
CONCLUSION: Mortality in unstable patients with pulmonary embolism appeared to be reduced with IVC filters only when the filter was inserted on the first or second day of admission. The design used for these analyses controlled for immortal time bias as a cause of the lower mortality with IVC filters.
PMID: 29906426 [PubMed - as supplied by publisher]