Associated bare stenting of distal aorta with a Djumbodis(®) system versus conventional surgery in type A aortic dissection

Late complications of the Djumbodis system in patients with type A acute aortic dissection

The Djumbodis system is a metallic stent designed to prevent false lumen dilatation after repair of acute aortic dissection. Although the exact number of Djumbodis stents inserted worldwide could not be ascertained from a review of the literature, available data indicate 9 specific device-related complications from 4 patient series and 3 case reports: stent deformity or fracture (4), progressive enlargement of the distal false lumen (3) and distal pseudoaneurysm (1); a further patient with pseudoaneurysm of the distal suture line is added from personal observation. The present review confirms the inability of the Djumbodis stent to provide reduction and/or elimination of the false lumen after repair of type A dissection, highlighting peculiar device-related complications. Current survivors with a Djumbodis stent should undergo close follow-up to prevent possible catastrophic events due to device failure.

ASPECTS OF THE USE OF PROPENSITY SCORE MATCHING METHODS IN NEUROSURGERY

ABSTRACT Objective Observational studies and register data provide researchers with ample opportunities to obtain answers to questions that randomized controlled trials cannot answer for organizational or ethical reasons. One of the most common tools for solving this problem is the use of propensity score matching (PSM) methods. The purposes of our study were to compare various models and algorithms for selecting PSM parameters, using retrospective clinical data, and to compare the results obtained using the PSM method with those of prospective studies. Methods The results of two studies (randomized prospective and retrospective) conducted at the Novosibirsk Research Institute of Traumatology and Orthopedics were used for comparative analysis. The trials aimed to study the effectiveness and safety of surgical treatment of degenerative dystrophic lesions in the lumbar spine. We compared the results using the recommended PSM parameters (caliper=0.2 and 0.6) the propensity score is the probability of assignment to one treatment conditional on a subject’s measured baseline covariates. Propensity-score matching is increasingly being used to estimate the effects of exposures using observational data. In the most common implementation of propensity-score matching, pairs of treated and untreated subjects are formed whose propensity scores differ by at most a pre-specified amount (the caliper widthand the caliper values often used in real-life studies (0.05, 0.1, 0.25, 0.5, and 0.8) with the those obtained in a similar prospective study. Results After eliminating systematic selection bias, the results of the retrospective and randomized prospective studies were qualitatively comparable. Conclusion The results of this study provide recommendations for the use of PSM: when evaluating efficacy scores in neurosurgical studies (with a sample size < 150 patients), we recommend matching on the logit of the propensity score using calipers of width equal to 0.6 of the standard deviation of the logit of the propensity score. Level of evidence V; Type of study is expert opinion.

Treatment with transfemoral bare-metal stent of residual aortic arch dissection after surgical repair of acute type an aortic dissection

Background

Here we evaluate the usefulness of transfemoral uncovered stent implantation to avoid secondary conventional surgery for residual type A aortic dissection (TAAD) of the aortic arch after ascending aorta replacement.

Methods

From June 2009 to April 2015, 11 patients were treated with transfemoral implantation of uncovered stents in the aortic arch after surgical replacement of ascending aorta performed on average 4.7±2.3 years earlier. An enlarged dissected aortic arch or a dangerous median growth of more than 5 mm/yr or impending rupture presenting as chest pain were indications for treatment. The dissected aortic tracts diameter must not exceed 45 mm. Five patients (45.5%) were treated with Djumbodies Dissection System, 6 patients (54.5%) with Jotec E-XL aortic stent.

Results

There were no perioperative deaths or permanent neurologic complications. Primary procedural success was obtained in all patients and the residual TAAD in aortic arch was obliterated, with disappearance of the false lumen. Median intensive care unit (ICU) stay was 24 hours; post-operative hospital stay was 5.2±1.4 days. One death, not aortic related, occurred during follow-up period (mean 5.2±1.9 years). Descending thoracic aorta diameter significantly increased in 3 patients (27.3%): one patient (9.0%) needed a secondary conventional surgery, the other 2 (18.2%) of a distal extension with PETTICOAT approach.

Conclusions

Endovascular approach with uncovered metal bare stent is surely an evolving strategy to perform a purely endovascular treatment, indicated only for treatment of an aortic arch with a diameter of less than 40 or 45 mm, to avoid progressive thoracic aortic dilatation and/or rupture.

[Evidence-based medicine: opportunities of the Propensity Score Matching (PSM) method in eliminating selection bias in retrospective neurosurgical studies]

To date, a large amount of retrospectively collected data about treatment of neurosurgical pathology have been accumulated. Modern methods of medical statistics are necessary for correct interpretation of the data. The article purpose is to demonstrate application of one of the modern methods, Propensity Score Matching (PSM), in neurosurgery. The use of PSM avoids misinterpretation of retrospectively collected data and obviates errors in planning further prospective studies. For the past 10 years, the number of published international PSM-based studies has increased more than 10-fold, with the number of articles by Russian authors accounting for less than 0.2%. In line with the tendencies of international studies, application of PSM in analysis of retrospectively collected data will enable testing of a number of hypotheses and correct planning of prospective randomized studies.