External validation of a quantitative model to guide patient selection for placement of an optional or permanent inferior vena ca va filter

Objectives: The objective of this study was to validate a previously published quantitative model that predicts the likelihood of an optional inferior vena cava filter (IVCF) being kept as a permanent device in a different patient population. Material and Methods: An institutional database of IVCF patients from 2016 to 2018 was reviewed. As in the published reference, if a retrieval was attempted, the IVCF was categorized as “removed;” if no attempt was performed, the filter was categorized as “kept permanent.” Patient parameters, such as age, sex, history of venous thromboembolism, presence of neurologic disease, presence of malignancy, as well as indications for IVCF placement were analyzed. The previously published formula was applied to analyze its ability to predict the likelihood of an optional IVCF being kept permanently in a new, external population. Results: A total of 270 patients were identified. Seventy-one filters were “removed” and 199 were “kept permanent.” Advanced age (odds ratio [OR] 1.05; 95% confidence interval [CI] 1.03–1.07) and presence of malignancy (OR 2.55; 95% CI 1.29–5.07) were the factors associated with the IVCF being “kept permanent” versus “removed.” None of the other parameters was statistically significant. The receiver operating characteristic curve yielded the area under the curve of 0.66, compared to the previously published value of 0.8. The sensitivity and specificity of the model were 64.3% and 62.0%, respectively. Conclusion: Advanced age and presence of malignancy were associated with optional IVCFs being kept as permanent devices. However, the previously published formula did not yield an accurate quantitative prediction in this external patient population.