Relationships between 2-Year Survival, Costs, and Outcomes following Carotid Endarterectomy in Asymptomatic Patients in the Vascular Quality Initiative

BACKGROUND

Carotid endarterectomy (CEA) for asymptomatic patients with limited life expectancy may not be beneficial or cost-effective. The purpose of this study was to examine relationships among survival, outcomes, and costs within 2 years following CEA among asymptomatic patients.

METHODS

Prospectively collected data from 3097 patients undergoing CEA for asymptomatic disease from Vascular Quality Initiative VQI registry were linked to Medicare. Models were used to identify predictors of 2-year mortality following CEA. Patients were classified as low, medium, or high risk of death based on this model. Next, we examined costs related to cerebrovascular care, occurrence of stroke, rehospitalization, and reintervention within 2 years following CEA across risk strata.

RESULTS

Overall, 2-year mortality was 6.7%. Age, diabetes, smoking, congestive heart failure (CHF), chronic obstructive pulmonary disease, renal insufficiency, absence of statin use, and contralateral internal carotid artery (ICA) stenosis were independently associated with a higher risk of death following CEA. In-hospital costs averaged $7500 among patients defined as low risk for death, and exceeded $10,800 among high risk patients. Although long-term costs related to cerebrovascular disease were 2 times higher in patients deemed high risk for death compared with low risk patents ($17,800 vs. $8800, P = 0.001), high risk of death was not independently associated with a high probability of high cost. Predictors of high cost at 2 years were severe contralateral ICA stenosis, dialysis dependence, and American Society for Anesthesia Class 4. Both statin use and CHF were protective of high cost.

CONCLUSIONS

Greater than 90% of patients undergoing CEA live long enough to realize the benefits of their procedure. Moreover, the long-term costs are supported by the effectiveness of this procedure at all levels of patient risk.

The relationship of regional hemoglobin A1c testing and amputation rate among patients with diabetes

Objective The risk of leg amputation among patients with diabetes has declined over the past decade, while use of preventative measures-such as hemoglobin A1c monitoring-has increased. However, the relationship between hemoglobin A1c testing and amputation risk remains unclear. Methods We examined annual rates of hemoglobin A1c testing and major leg amputation among Medicare patients with diabetes from 2003 to 2012 across 306 hospital referral regions. We created linear regression models to study associations between hemoglobin A1c testing and lower extremity amputation. Results From 2003 to 2012, the proportion of patients who received hemoglobin A1c testing increased 10% (74% to 84%), while their rate of lower extremity amputation decreased 50% (430 to 232/100,000 beneficiaries). Regional hemoglobin A1c testing weakly correlated with crude amputation rate in both years (2003 R = -0.20, 2012 R = -0.21), and further weakened with adjustment for age, sex, and disability status (2003 R = -0.11, 2012 R = -0.17). In a multivariable model of 2012 amputation rates, hemoglobin A1c testing was not a significant predictor. Conclusion Lower extremity amputation among patients with diabetes nearly halved over the past decade but only weakly correlated with hemoglobin A1c testing throughout the study period. Better metrics are needed to understand the relationship between preventative care and amputation.

The Prevalence and Regional Variation of Major Depressive Disorder Among Patients With Peripheral Arterial Disease in the Medicare Population

Background:

Current evidence suggests an association between coronary artery disease and major depressive disorder (MDD). Data to support a similar association between peripheral arterial disease (PAD) and MDD are more limited. This study examines the prevalence and regional variation of both PAD and MDD in a large contemporary patient sample.

Methods:

All Medicare claims, part A and B, from January 2009 until December 2011 were queried using diagnosis codes specific for a previously validated clinical algorithm for PAD and major depression. Codes for PAD included those specific to cerebrovascular disease, abdominal aortic aneurysm, and peripheral vascular disease. Peripheral arterial disease prevalence, major depression prevalence, and coprevalence rates were determined, respectively. Regional variation of both conditions was determined using zip code data to identify potential endemic areas of disease intensity for both diagnoses.

Results:

Over the study interval, the percentage of Medicare beneficiaries with a diagnosis of PAD remained relatively constant (3.0%-3.7%, n = 0.85-1.06 million in part A and 17.4%-17.5%, n = 4.82-4.93 million in part B), and MDD showed a similar trend (1.6%-2.7%, n = 0.46-0.79 million in part A and 6.1%-6.7%, n = 1.69-1.90 million in part B). The observed rate of MDD in those with an established diagnosis of PAD was 5-fold higher than those without PAD in part A claims (1.8-fold in part B claims). Moreover, there was a significant linear geographic correlation among patients with PAD and MDD ( r = .54, P ≤ .01).

Conclusions:

This study documents a correlation between PAD and MDD and may, therefore, identify an at-risk population susceptible to inferior clinical outcomes. Significant regional variation exists in the prevalence of PAD and MDD, though there appear to be specific endemic regions notable for both disorders. Accordingly, health-care resource allocation toward endemic regions may help improve population health among this at-risk cohort.

Abstract 109: Statins Have a Dose-dependent Effect on Amputation Risk and Survival in Peripheral Arterial Disease (PAD) Patients

Introduction: Statin dose guidelines for PAD patients are based on coronary artery disease and stroke data. The aim of our study was to determine the effect of statin dose (based on 2013 ACC/AHA guidelines) on PAD outcomes of amputation and mortality.

Methods: Patients with PAD in the Veterans Affairs database were identified from 2003-2014. The exposure was highest statin dose usage (none, low-moderate and high intensity) around diagnosis of PAD (within 1 year). The outcomes were risk of incident amputation (below knee or above knee) and mortality at 1, 3 and 5 years. The effect of statin dose on the two outcomes was also analyzed using Cox proportional hazards modeling to adjust for covariates.

Results: In 208,275 patients with PAD [Males: 98.1%; Mean age: 67.4 yrs (SD 9.9)], 17,643 amputations and 99,951 deaths occurred in a median follow up of 5.2 years. Almost a quarter (27.7%) of patients were not on a statin while 30.4% were on simvastatin 80 mg (no longer recommended due to drug toxicity). The risk of incident amputation declined significantly at the high intensity statin dose as seen in Table 1. In Cox models adjusting for age, gender, race, comorbidities, cholesterol levels and creatinine, the high intensity statins were associated with lower amputation risk and mortality as compared to no statin [HR 0.67; 95% CI (0.63, 0.72) and HR 0.71; 95% CI (0.68, 0.73), respectively]. Low-moderate-dose statins also had significant but smaller reductions in risk of amputation and mortality [HR amputation 0.78 (0.75, 0.82), HR death 0.78 (0.77, 0.80)].

Conclusion: This is one of the largest population based studies to examine the effect of statins on long-term PAD outcomes and the first to explore the dose-dependent effect of statins on amputation and mortality. High intensity statins are associated with a significant reduction in limb loss and mortality in PAD patients followed by a smaller risk reduction by low-moderate intensity statins as compared to no statin therapy.

Dual antiplatelet therapy reduces stroke but increases bleeding at the time of carotid endarterectomy

OBJECTIVE

Controversy persists regarding the perioperative management of clopidogrel among patients undergoing carotid endarterectomy (CEA). This study examined the effect of preoperative dual antiplatelet therapy (aspirin and clopidogrel) on in-hospital CEA outcomes.

METHODS

Patients undergoing CEA in the Vascular Quality Initiative were analyzed (2003-2014). Patients on clopidogrel and aspirin (dual therapy) were compared with patients taking aspirin alone preoperatively. Study outcomes included reoperation for bleeding and thrombotic complications defined as transient ischemic attack (TIA), stroke, or myocardial infarction. Secondary outcomes were in-hospital death and composite stroke/death. Univariate and multivariable analyses assessed differences in demographics and operative factors. Propensity score-matched cohorts were derived to control for subgroup heterogeneity.

RESULTS

Of 28,683 CEAs, 21,624 patients (75%) were on aspirin and 7059 (25%) were on dual therapy. Patients on dual therapy were more likely to have multiple comorbidities, including coronary artery disease (P < .001), congestive heart failure (P < .001), and diabetes (P < .001). Patients on dual therapy were also more likely to have a drain placed (P < .001) and receive protamine during CEA (P < .001). Multivariable analysis showed that dual therapy was independently associated with increased reoperation for bleeding (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.20-2.42; P = .003) but was protective against TIA or stroke (OR, 0.61; 95% CI, 0.43-0.87; P = .007), stroke (OR, 0.63; 95% CI, 0.41-0.97; P = .03), and stroke/death (OR, 0.66; 95% CI, 0.44-0.98; P = .04). Propensity score matching yielded two groups of 4548 patients and showed that patients on dual therapy were more likely to require reoperation for bleeding (1.3% vs 0.7%; P = .004) but less likely to suffer TIA or stroke (0.9% vs 1.6%; P = .002), stroke (0.6% vs 1.0%; P = .04), or stroke/death (0.7% vs 1.2%; P = .03). Within the propensity score-matched groups, patients on dual therapy had increased rates of reoperation for bleeding regardless of carotid symptom status. However, asymptomatic patients on dual therapy demonstrated reduced rates of TIA or stroke (0.6% vs 1.5%; P < .001), stroke (0.4% vs 0.9%; P = .01), and composite stroke/death (0.5% vs 1.0%; P = .02). Among propensity score-matched patients with symptomatic carotid disease, these differences were not statistically significant.

CONCLUSIONS

Preoperative dual antiplatelet therapy was associated with a 40% risk reduction for neurologic events but also incurred a significant increased risk of reoperation for bleeding after CEA. Given its observed overall neurologic protective effect, continued dual antiplatelet therapy throughout the perioperative period is justified. Initiating dual therapy in all patients undergoing CEA may lead to decreased neurologic complication rates.

Smoking cessation strategies in vascular surgery

Tobacco abuse is a highly prevalent modifiable risk factor in vascular surgery patient populations. Despite the known benefits of smoking cessation, quitting smoking is difficult for most patients. Physician advice to stop smoking can help, though more intensive or multifactorial interventions have greater impact. Smoking cessation initiatives based in vascular clinics are feasible, although currently there is significant variation in physician delivery of smoking cessation interventions. Vascular surgeons are optimally poised to be able to capitalize on the "teachable moment" of the vascular procedure to encourage smoking cessation. Concise and effective smoking cessation strategies include standardized physician "very brief advice" (a standardized advice delivery developed and validated by the National Health Service), referral to telephone counseling, and prescription of pharmacotherapy, all of which are best utilized together. This review will discuss different smoking cessation strategies, as well as their inclusion in multicenter trials designed to study delivery of smoking cessation interventions in vascular surgery patients.

Use of a glucose management service improves glycemic control following vascular surgery: an interrupted time-series study

BACKGROUND

The optimal method for obtaining good blood glucose control in noncritically ill patients undergoing peripheral vascular surgery remains a topic of debate for surgeons, endocrinologists, and others involved in the care of patients with peripheral arterial disease and diabetes. A prospective trial was performed to evaluate the impact of routine use of a glucose management service (GMS) on glycemic control within 24 hours of lower-extremity revascularization (LER).

METHODS

In an interrupted time-series design (May 1, 2011-April 30, 2012), surgeon-directed diabetic care (Baseline phase) to routine GMS involvement (Intervention phase) was compared following LER. GMS assumed responsibility for glucose management through discharge. The main outcome measure was glycemic control, assessed by (1) mean hospitalization glucose and (2) the percentage of recorded glucose values within target range. Statistical process control charts were used to assess the impact of the intervention.

RESULTS

Clinically important differences in patient demographics were noted between groups; the 19 patients in the Intervention arm had worse peripheral vascular disease than the 19 patients in the Baseline arm (74% critical limb ischemia versus 58%; p = .63). Routine use of GMS significantly reduced mean hospitalization glucose (191 mg/dL Baseline versus 150 mg/dL Intervention, p < .001). Further, the proportion of glucose values in target range increased (48% Baseline versus 78% Intervention, p = .05). Following removal of GMS involvement, measures of glycemic control did not significantly decrease for the 19 postintervention patients.

CONCLUSIONS

Routine involvement of GMS improved glycemic control in patients undergoing LER. Future work is needed to examine the impact of improved glycemic control on clinical outcomes following LER.

Preoperative antiplatelet and statin treatment was not associated with reduced myocardial infarction after high-risk vascular operations in the Vascular Quality Initiative

OBJECTIVE

Medical management with antiplatelet (AP) and statin therapy is recommended for nearly all patients undergoing vascular surgery to reduce cardiovascular events. We assessed the association between preoperative use of AP and statin medications and postoperative in-hospital myocardial infarction (MI) in patients undergoing high-risk open surgery.

METHODS

We studied patients who underwent elective suprainguinal (n = 3039) and infrainguinal (n = 8323) bypass and open infrarenal abdominal aortic aneurysm repair (n = 3007) in the Vascular Quality Initiative (VQI, 2005-2014). We assessed the association between AP or statin use and in-hospital postoperative MI and MI/death. Multivariable logistic analyses were performed to identify the patient, procedure, and preoperative medication factors associated with postoperative MI and MI/death across procedures and patient cardiac risk strata. Secondary end points included bleeding, transfusion, and thrombotic complications.

RESULTS

Most patients were taking both AP and statin preoperatively (56% both agents vs 19% AP only, 13% statin only, and 12% neither agent). Use of both agents was more common for patients in the highest cardiac risk stratum (low, 54%; intermediate, 59%; high, 61%; P < .01). Increased cardiac risk was associated with higher MI rates (1.8% vs 3.8% vs 6.5% for low, intermediate, and high risk; P < .01). By univariate analysis, MI rate was paradoxically higher for patients taking both agents (3.7%, vs statin only 2.8%, AP only 2.6%, or neither AP nor statin 2.4%; P = .003). After multivariable adjustment, rates of MI in patients taking preoperative AP only (odds ratio [OR], 0.9; 95% confidence interval [CI], 0.7-1.2) and statin only (OR, 0.8; 95% CI, 0.6-1.2) were not different from those in patients taking either or neither medication (neither agent compared with taking both agents: OR, 1.0; 95% CI, 0.7-1.4; P > .05 for all). Similarly, rates of MI/death were not associated with medication status after multivariable adjustment. Estimated blood loss >1 liter (OR, 2.4; 95% CI, 1.6-3.7; P < .01) and transfusions of 1 or 2 units (OR, 2.5; 95% CI, 2.0-3.3; P < .01) and ≥3 units (OR, 4.0; 95% CI, 3.1-5.3; P < .01) were highly associated with MI, with similar findings related to composite MI/death in multivariable analysis. Rates of blood loss were slightly higher with AP use for all procedures; however, increased transfusions occurred only for infrainguinal bypass with AP use. Rates of reoperation for bleeding, graft thrombosis, or graft revision did not differ by preoperative AP use.

CONCLUSIONS

Preoperative AP and statin medications as used in VQI were not associated with the rate of in-hospital MI/death after major open vascular operations. Rather, predicted cardiac risk and operative blood loss were significantly associated with in-hospital MI or MI/death. AP and statin medications appear to be more useful in reducing late mortality than early postoperative MI/death in VQI. However, they were not harmful, so their long-term benefit argues for continued use.

Readmission destination and risk of mortality after major surgery: an observational cohort study

BACKGROUND

Hospital readmissions are common after major surgery, although it is unknown whether patients achieve improved outcomes when they are readmitted to, and receive care at, the index hospital where their surgical procedure was done. We examined the association between readmission destination and mortality risk in the USA in Medicare beneficiaries after a range of common operations.

METHODS

By use of claims data from Medicare beneficiaries in the USA between Jan 1, 2001, and Nov 15, 2011, we assessed patients who needed hospital readmission within 30 days after open abdominal aortic aneurysm repair, infrainguinal arterial bypass, aortobifemoral bypass, coronary artery bypass surgery, oesophagectomy, colectomy, pancreatectomy, cholecystectomy, ventral hernia repair, craniotomy, hip replacement, or knee replacement. We used logistic regression models incorporating inverse probability weighting and instrumental variable analysis to measure associations between readmission destination (index vs non-index hospital) and risk of 90 day mortality for patients who underwent surgery who needed hospital readmission.

FINDINGS

9,440,503 patients underwent one of 12 major operations, and the number of patients readmitted or transferred back to the index hospital where their operation was done varied from 186,336 (65·8%) of 283,131 patients who were readmitted after coronary artery bypass grafting, to 142,142 (83·2%) of 170,789 patients who were readmitted after colectomy. Readmission was more likely to be to the index hospital than to a non-index hospital if the readmission was for a surgical complication (189,384 [23%] of 834,070 patients readmitted to index hospital vs 36,792 [13%] of 276,976 patients readmitted non-index hospital, p<0·0001). Readmission to the index hospital was associated with a 26% lower risk of 90 day mortality than was readmission to a non-index hospital, with inverse probability weighting used to control for selection bias (odds ratio [OR] 0·74, 95% CI 0·66-0·83). This effect was significant (p<0·0001) for all procedures in inverse probability-weighted models, and was largest for patients who were readmitted after pancreatectomy (OR 0·56, 95% CI 0·45-0·69) and aortobifemoral bypass (OR 0·69, 95% CI 0·61-0·77). By use of hospital-level variation among regional index hospital readmission rates as an instrument, instrumental variable analysis showed that the patients with the highest probability of returning to the index hospital had 8% lower risk of mortality (OR 0·92 95% CI 0·91-0·94) than did patients who were less likely to be readmitted to the index hospital.

INTERPRETATION

In the USA, patients who are readmitted to hospital after various major operations consistently achieve improved survival if they return to the hospital where their surgery took place. These findings might have important implications for cost-effectiveness-driven regional centralisation of surgical care.

FUNDING

None.