Risk Factors for Venous Thromboembolism after Vascular Surgery and Implications for Chemoprophylaxis Strategies

OBJECTIVE

Venous thromboembolism (VTE) is an important cause of postoperative morbidity and mortality, but the reported incidence after major vascular surgery ranges from as low as 1% to upwards of 10%. Further, little is known about optimal chemoprophylaxis regimens or rates of post-discharge VTE in this population. This study aimed to better characterize in-hospital and post-discharge VTE after major vascular surgery, the role of chemoprophylaxis timing, and the association of VTE with mortality.

METHODS

A single center retrospective study of 1,449 major vascular operations (2013-2020) was performed, and included 189 EVARs (13%), 169 TEVARs (12%), 318 open aortic operations (22%), 640 lower extremity bypasses (44%), and 133 femoral endarterectomies (9%). Baseline characteristics, anticoagulant/antiplatelet medications, and outcomes were abstracted from an electronic data warehouse with medical chart auditing. Post-operative VTE (pulmonary embolism [PE] and deep vein thrombosis [DVT]) within 90-days of surgery was classified based on location, symptoms, and treatment. Cut point analysis using Youden's index identified the most VTE discriminating timing of chemoprophylaxis (including therapeutic/prophylactic anticoagulant and antiplatelet medications) and Caprini score. Multivariable logistic regression tested the association of VTE with chemoprophylaxis timing, Caprini score, and additional risk factors. Cox proportional hazard modeling measured the association between VTE and mortality.

RESULTS

Overall VTE incidence was 3.4% (65% DVTs, 25% PEs, 10% both) and 37% were post-discharge. The rate of symptomatic VTE was 2.4%, which was lowest for EVAR (0.0%) and highest for open aortic operations (4.1%, p=0.02). Individuals who developed VTE had longer length of stay, higher rates of end-stage renal disease, prior VTE, and higher Caprini scores (8 vs 5 points) (all p<0.01). Individuals who developed VTE were also more likely to receive >2 units of blood postoperatively, have an unplanned return to the operating room, have delayed chemoprophylaxis/anticoagulation/antiplatelet initiation >4 days postoperatively, and had increased 90-day mortality (all p<0.01). Caprini score >7 (29% of patients) was associated with post-discharge VTE (2.6% vs 0.7%, p=0.01), and chemoprophylaxis/anticoagulation/antiplatelet timing >4 days was associated with increased adjusted odds of VTE (odds ratio 2.4 [1.1-4.9]). Although no fatal VTEs were identified, VTE was an independent predictor of 90-day mortality (adjusted hazard ratio 2.7 [1.3-5.9]).

CONCLUSIONS

These data highlight that patients undergoing major vascular surgery are particularly prone to VTE with frequent hypercoagulable comorbidities and earlier initiation of chemoprophylaxis is associated with reduced risk of development of VTE. Furthermore, post-discharge VTE rates may reach thresholds warranting post-discharge chemoprophylaxis, particularly for patients with Caprini scores >7.

Aortic Neck IFU Violations During EVAR for Ruptured Infrarenal Aortic Aneurysms are Associated with Increased In-Hospital Mortality

OBJECTIVE

Vascular surgeons treating patients with ruptured abdominal aortic aneurysm must make rapid treatment decisions and sometimes lack immediate access to endovascular devices meeting the anatomic specifications of the patient at hand. We hypothesized that endovascular treatment of ruptured abdominal aortic aneurysm (rEVAR) outside manufacturer instructions-for-use (IFU) guidelines would have similar in-hospital mortality compared to patients treated on-IFU or with an infrarenal clamp during open repair (ruptured open aortic aneurysm repair [rOAR]).

METHODS

Vascular Quality Initiative datasets for endovascular and open aortic repair were queried for patients presenting with ruptured infrarenal AAA between 2013-2018. Graft-specific IFU criteria were correlated with case-specific proximal neck dimension data to classify rEVAR cases as on- or off-IFU. Univariate comparisons between the on- and off-IFU groups were performed for demographic, operative and in-hospital outcome variables. To investigate mortality differences between rEVAR and rOAR approaches, coarsened exact matching was used to match patients receiving off-IFU rEVAR with those receiving complex rEVAR (requiring at least one visceral stent or scallop) or rOAR with infrarenal, suprarenal or supraceliac clamps. A multivariable logistic regression was used to identify factors independently associated with in-hospital mortality.

RESULTS

621 patients were treated with rEVAR, with 65% classified as on-IFU and 35% off-IFU. The off-IFU group was more frequently female (25% vs. 18%, P = 0.05) and had larger aneurysms (76 vs. 72 mm, P= 0.01) but otherwise was not statistically different from the on-IFU cohort. In-hospital mortality was significantly higher in patients treated off-IFU vs. on-IFU (22% vs. 14%, P= 0.02). Off-IFU rEVAR was associated with longer operative times (135 min vs. 120 min, P= 0.004) and increased intraoperative blood product utilization (2 units vs. 1 unit, P= 0.002). When off-IFU patients were matched to complex rEVAR and rOAR patients, no baseline differences were found between the groups. Overall in-hospital complications associated with off-IFU were reduced compared to more complex strategies (43% vs. 60-81%, P< 0.001) and in-hospital mortality was significantly lower for off-IFU rEVAR patients compared to the supraceliac clamp group (18% vs. 38%, P= 0.006). However, there was no significantly increased mortality associated with complex rEVAR, infrarenal rOAR or suprarenal rOAR compared to off-IFU rEVAR (all P> 0.05). This finding persisted in a multivariate logistic regression.

CONCLUSIONS

Off-IFU rEVAR yields inferior in-hospital survival compared to on-IFU rEVAR but remains associated with reduced in-hospital complications when compared with more complex repair strategies. When compared with matched patients undergoing rOAR with an infrarenal or suprarenal clamp, survival was no different from off-IFU rEVAR. Taken together with the growing available evidence suggesting reduced long-term durability of off-IFU EVAR, these data suggest that a patient's comorbidity burden should be key in making the decision to pursue off-IFU rEVAR over a more complex repair when proximal neck violations are anticipated preoperatively.

Understanding value and patient complexity among common inpatient vascular surgery procedures

OBJECTIVE

Vascular surgery patients are highly complex, second only to patients undergoing cardiac procedures. However, unlike cardiac surgery, work relative value units (wRVU) for vascular surgery were undervalued based on an overall patient complexity score. This study assesses the correlation of patient complexity with wRVUs for the most commonly performed inpatient vascular surgery procedures.

METHODS

The 2014 to 2017 National Surgical Quality Improvement Program Participant Use Data Files were queried for inpatient cases performed by vascular surgeons. A previously developed patient complexity score using perioperative domains was calculated based on patient age, American Society of Anesthesiologists class of ≥4, major comorbidities, emergent status, concurrent procedures, additional procedures, hospital length of stay, nonhome discharge, and 30-day major complications, readmissions, and mortality. Procedures were assigned points based on their relative rank and then an overall score was created by summing the total points. An observed to expected ratio (O/E) was calculated using open ruptured abdominal aortic aneurysm repair (rOAAA) as the referent and then applied to an adjusted median wRVU per operative minute.

RESULTS

Among 164,370 cases, patient complexity was greatest for rOAAA (complexity score = 128) and the least for carotid endarterectomy (CEA) (complexity score = 29). Patients undergoing rOAAA repair had the greatest proportion of American Society of Anesthesiologists class of ≥IV (84.8%; 95% confidence interval [CI], 82.6%-86.8%), highest mortality (35.5%; 95% CI, 32.8%-38.3%), and major complication rate (87.1%; 95% CI, 85.1%-89.0%). Patients undergoing CEA had the lowest mortality (0.7%; 95% CI, 0.7%-0.8%), major complication rate (8.2%; 95% 95% CI, 8.0%-8.5%), and shortest length of stay (2.7 days; 95% CI, 2.7-2.7). The median wRVU ranged from 10.0 to 42.1 and only weakly correlated with overall complexity (Spearman's ρ = 0.11; P < .01). The median wRVU per operative minute was greatest for thoracic endovascular aortic repair (0.25) and lowest for both axillary-femoral artery bypass (0.12) and open femoral endarterectomy, thromboembolectomy, or reconstruction (0.12). After adjusting for patient complexity, CEA (O/E = 3.8) and transcarotid artery revascularization (O/E = 2.8) had greater than expected O/E. In contrast, lower extremity bypass (O/E = 0.77), lower extremity embolectomy (O/E = 0.79), and open abdominal aortic repair (O/E = 0.80) had a lower than expected O/E.

CONCLUSIONS

Patient complexity varies substantially across vascular procedures and is not captured effectively by wRVUs. Increased operative time for open procedures is not adequately accounted for by wRVUs, which may unfairly penalize surgeons who perform complex open operations.

Depression Predicts Non-Home Discharge After Abdominal Aortic Aneurysm Repair

BACKGROUND

Mental health's impact on vascular surgical patients has long been overlooked. While outside the expertise of most surgeons, understanding the role that depression plays in the postoperative course could provide additional insight into opportunities to improve surgical outcomes and healthcare value. Additionally, non-home discharge (NHD) to a rehabilitation or skilled nursing facility after surgery is associated with impaired quality of life and higher postdischarge complications, readmissions, and mortality. We hypothesized that depression would be associated with an increased risk for NHD following abdominal aortic aneurysm (AAA) repair.

METHODS

Nonruptured AAA repair cases were identified from the National Inpatient Sample (NIS) using ICD-9 codes between 2005 and 2014. Depression, comorbidities, postoperative complications, and discharge destination were evaluated using statistical tests as appropriate to the data. A hierarchical multivariable logistic regression controlling for hospital level variation was used to examine the independent association between depression, and the primary outcome of NHD controlling for median income and confounders meeting P < 0.05 on univariate analysis.

RESULTS

There were 99,934 total cases analyzed, of which 4,755 (4.8%) were diagnosed with depression and 10,618 (11.9%) required NHD. Patients with depression were younger, more likely to be women, white, have diabetes, chronic obstructive pulmonary disease, hypertension, tobacco use, and more likely to experience a postoperative complication. On adjusted multivariable analysis, patients with depression were more likely to require NHD (odds ratio [OR] 1.87, 95% confidence interval [CI]: 1.68-2.08, c-statistic = 0.82). On stratified analysis by operative approach, depression had a larger effect estimate in endovascular repair (OR 2.19; 95% CI: 1.90-2.52) versus open repair (OR 1.60; 95% CI: 1.38-1.87).

CONCLUSIONS

In a nationally representative sample, patients with depression were more likely to require NHD after AAA repair. This study highlights the importance that depression plays in postoperative outcomes after AAA repair. Furthermore, addressing mental health preoperatively has the potential to improve outcomes in patients undergoing AAA repair.

Patients with depression are less likely to go home after critical limb revascularization

BACKGROUND

Although often overlooked during the preoperative evaluation, recent evidence has suggested that depression in patients with peripheral artery disease is associated with increased postoperative complications, including decreased primary and secondary patency after revascularization and an increased risk of major amputation and mortality. Postoperative nonhome discharge (NHD) is an important outcome for patients and has also been associated with other adverse outcomes; however, the effect that depression has on NHD after vascular surgery has remained unexplored. We hypothesized that depression would be associated with an increased risk of NHD after revascularization for chronic limb threatening ischemia (CLTI).

METHODS

Endovascular, open, and hybrid (combined open and endovascular) cases of revascularization for CLTI were identified from the 2012 to 2014 National (Nationwide) Inpatient Sample. CLTI, diagnoses of depression, and medical comorbidities were defined using the corresponding International Classification of Diseases, Ninth Revision, Clinical Modification codes. A hierarchical multivariable binary logistic regression controlling for hospital level variation and for confounders meeting P <.01 on bivariate analysis was used to examine the association between depression and NHD. A sensitivity analysis after coarsened exact matching for baseline characteristics that differed between the two groups was performed to reduce any imbalance.

RESULTS

A total of 64,817 cases were identified, of which 5472 (8.4%) included a diagnosis of depression and 16,524 (25.5%) NHD. The patients with depression were younger and more likely to be women and white, have multiple comorbidities and a nonelective admission, and experience a postoperative complication (P <.05). On unadjusted analyses, patients with depression had an 8% absolute increased risk of requiring NHD (32.1% vs 24.9%; P <.001). On multivariable analysis, patients with depression had an increased odds for NHD (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.40-1.61; c-statistic, 0.81) compared with those without depression. After stratification by operative approach, depression had a larger effect estimate in endovascular revascularization (OR, 1.57; 95% CI, 1.42-1.74) compared with open (OR, 1.45; 95% CI, 1.30-1.62). A test for interaction between depression and gender identified that men with depression had greater odds of NHD compared with women with depression (OR, 1.68; 95% CI, 1.51-1.88; vs OR, 1.37; 95% CI, 1.25-1.51; interaction P <.01). A sensitivity analysis after coarsened exact matching confirmed these findings.

CONCLUSIONS

To the best of our knowledge, the present study is the first to identify an association between depression and NHD after revascularization for CLTI. These results provide further evidence of the negative effects that comorbid depression has on patients undergoing revascularization for CLTI. Future studies should examine whether treating depression can improve the outcomes in this patient population.

A novel preoperative risk score for nonhome discharge after elective thoracic endovascular aortic repair

BACKGROUND

Nonhome discharge (NHD) to a rehabilitation or skilled nursing facility after vascular surgery is poorly described despite its large impact on patients. Understanding postsurgical NHD risk is essential to providing adequate preoperative counseling and shared decision making, particularly for elective surgeries. We aimed to identify independent predictors of NHD after elective thoracic endovascular aortic repair (TEVAR) for thoracic aortic aneurysms (TAA) and to create a clinically useful preoperative risk score.

METHODS

Elective TEVAR cases for descending TAA were queried from the Society for Vascular Surgery Vascular Quality Initiative from 2014 to 2018. A risk score was created by splitting the dataset into two-thirds for model development and one-third for validation. A parsimonious stepwise hierarchical multivariable logistic regression controlling for hospital level variation was performed in the development dataset, and the beta-coefficients were used to assign points for a risk score. This score was then cross-validated and model performance assessed.

RESULTS

Overall, 1469 patients were included and 213 (14.5%) required NHD. At baseline, patients who required NHD were more likely to be ≥80 years old (35.2% vs 19.4%), female (58.7% vs 40.6%), functionally dependent (42.3% vs 24.0%), and anemic (46.5% vs 27.8%), and to have chronic obstructive pulmonary disease (41.3% vs 33.4%), congestive heart failure (18.8% vs 11.1%), and American Society of Anesthesiologists class ≥4 (51.6% vs 39.8%; all P < .05). Multivariable analysis in the development group identified independent predictors of NHD that were used to create an 18-point risk score. Patients were stratified into three groups based upon their risk score: low risk (0-7 points; n = 563) with an NHD rate of 4.3%, moderate risk (8-11 points; n = 701) with an NHD rate of 17.0%, and high risk (≥12 points; n = 205) with an NHD rate of 34.2%. The risk score had good predictive ability with a c-statistic of 0.75 for model development and a c-statistic of 0.72 in the validation dataset.

CONCLUSIONS

This novel risk score can predict NHD after TEVAR for TAA using characteristics that can be identified preoperatively. The use of this score may allow for improved risk assessment, preoperative counseling, and shared decision making.

Living in a Food Desert is Associated with 30-day Readmission after Revascularization for Chronic Limb-Threatening Ischemia

BACKGROUND

Living in a food desert has been associated with increased cardiovascular risk; however, its impact on vascular surgery outcomes is unknown. This study hypothesized that living in a food desert would be associated with increased postoperative complications in patients undergoing revascularization for chronic limb-threatening ischemia (CLTI).

METHODS

This was a single-center retrospective analysis of open and endovascular infrainguinal revascularization for CLTI between April 2013 and December 2015. A food desert was defined using the US Department of Agriculture's Food Access Research Atlas. Bivariate analyses were performed appropriate to the data. Binary logistic regression was performed assessing the association of food desert status with 30-day postoperative complications.

RESULTS

In total, 152 cases were included, of which 17% (n = 26) resided in food deserts. Patients in the food desert cohort were less likely to be low income (27% vs. 54%, P = 0.01). Living in a food desert was associated with increased 30-day readmission [(39% vs. 20%, P = 0.04), unadjusted OR: 2.5 (CI: 1.0-6.2)]. FD cases also had a higher proportion of wound complications [12 (46%) vs. 28 (22%), P = 0.01)]. The overall wound complication rate was 27% with the majority being due to infections (63%). On multivariable analysis, food desert status remained associated with increased odds of 30-day readmission (OR: 2.7, CI: 1.2-8.4, P = 0.047). Reasons for readmission in the food desert group were all due to wound complications (100% vs. 72%, P = 0.08).

CONCLUSIONS

Living in a food desert was associated with nearly three times the odds of 30-day readmission after lower extremity revascularization for CLTI. This increase in readmission may be explained through increased wound complications. These findings support considering access to healthy food as a potential modifiable risk factor for adverse outcomes, particularly in CLTI revascularization.

Patient complexity by surgical specialty does not correlate with work relative value units

BACKGROUND

Understanding the differences in how patient complexity varies across surgical specialties can inform policy decisions about appropriate resource allocation and reimbursement. This study evaluated variation in patient complexity across surgical specialties and the correlation between complexity and work relative value units.

STUDY DESIGN

The 2017 American College of Surgeons National Surgical Quality Improvement Program was queried for cases involving otolaryngology and general, neurologic, vascular, cardiac, thoracic, urologic, orthopedic, and plastic surgery. A total of 10 domains of patient complexity were measured: American Society of Anesthesiologists class ≥4, number of major comorbidities, emergency operation, major complications, concurrent procedures, additional procedures, length of stay, non-home discharge, readmission, and mortality. Specialties were ranked by their complexity domains and the domains summed to create an overall complexity score. Patient complexity then was evaluated for correlation with work relative value units.

RESULTS

Overall, 936,496 cases were identified. Cardiac surgery had the greatest total complexity score and was most complex across 4 domains: American Society of Anesthesiologists class ≥4 (78.5%), 30-day mortality (3.4%), major complications (56.9%), and mean length of stay (9.8 days). Vascular surgery had the second greatest complexity score and ranked the greatest on the domains of major comorbidities (2.7 comorbidities) and 30-day readmissions (10.1%). The work relative value units did not correlate with overall complexity score (Spearman's ρ = 0.07; P < .01). Although vascular surgery had the second most complex patients, it ranked fifth greatest in median work relative value units. Similarly, general surgery was the fifth most complex but had the second-least median work relative value units.

CONCLUSION

Substantial differences exist between patient complexity across specialties, which do not correlate with work relative value units. Physician effort is determined largely by patient complexity, which is not captured appropriately by the current work relative value units.

Risk score for nonhome discharge after lower extremity bypass

OBJECTIVE

Patients undergoing lower extremity bypass (LEB) for peripheral artery disease require intensive health care resource utilization including rehabilitation and skilled nursing facilities. However, few studies have evaluated factors that lead to nonhome discharge (NHD) in this population of patients. This study sought to predict NHD by preoperative risk factors in patients undergoing LEB for peripheral artery disease using a novel risk score.

METHODS

The Vascular Study Group of New England database was queried for elective LEB for peripheral artery disease including claudication and critical limb ischemia from 2003 to 2017. Patients were excluded if the procedure was not elective, if they were not admitted from home, if they were bedridden, or if they died during the index admission. Only preoperative factors were considered in the analysis. The primary end point was NHD including rehabilitation and skilled nursing facilities. Data were split two-thirds for model derivation and one-third for validation. In the derivation cohort, bivariate analysis assessed the association of preoperative factors with NHD. A parsimonious manual stepwise binary logistic regression for NHD aimed at maximizing the C statistic while maintaining model simplicity was performed. A risk score was developed using the β coefficients and applied to the validation data set. The risk score performance was assessed using a C statistic and Hosmer-Lemeshow test for model fit.

RESULTS

There were 10,145 cases included with an overall NHD rate of 26.4% (n = 2676). Mean age was 66 years (range, 41-90 years). NHD patients were older (72 years vs 64 years; P < .01) and more frequently male (57.2% vs 42.8%; P < .01) and nonwhite (16.1% vs 9.9%; P < .01); they more frequently had tissue loss (54.2% vs 23.0%; P < .01), anemia (16.0% vs 5.3%; P < .01), severe cardiac comorbidity (21.8% vs 10.5%; P < .01), and insulin-dependent diabetes (33.3% vs 18.2%; P < .01). On multivariable analysis, factors associated with NHD included age, sex, nonwhite race, tissue loss, cardiac comorbidity, partial ambulatory deficit, and insulin-dependent diabetes. The C statistic was 0.78 in the derivation group and 0.79 in the validation group, with Hosmer-Lemeshow P > .999. The risk score ranged from 0 to 18, with a mean score of 4 (standard deviation ±3.5). The risk score was divided into low risk (0-4 points; n = 5272 [52%]; NHD = 10.1%]), moderate risk (5-9 points; n = 3663 [36.7%]; NHD = 36.7%), and high risk (≥10 points; n = 1210 [11.9%]; NHD = 66.1%).

CONCLUSIONS

This novel risk score was highly predictive for NHD after LEB for peripheral artery disease using only preoperative comorbidities. High-risk patients account for 12% of LEB but nearly a third of all patients requiring NHD. This risk score can be used preoperatively to determine high-risk patients for NHD, which may help improve preoperative counseling and hospital efficiency by allocating resources appropriately.