Effect Of Center Volume Research Articles

Inter-observer differences in interpretation of coronary pressure-wire pullback data by non-expert interventional cardiologists.

The physiological pattern of coronary artery disease as determined by pressure-wire (PW)-pullback is important for decision-making of revascularization and risk stratification of patients. However, it remains unclear whether inter-observer differences in interpreting PW-pullback data are subject to the expertise of physicians. This study sought to investigate the subjectivity of this assessment among non-experts. Expert interventional cardiologists classified 545 PW-pullback traces into physiologically focal or physiologically diffuse disease pattern. Defining expert-consensus as the reference standard, we evaluated ten non-expert doctors' classification performance. Observers were stratified equally by two ways: (i) years of experience as interventional cardiologists (middle-level vs. junior-level) and (ii) volume of institutions where they belonged to (high-volume center vs. low-volume center). When judged against the expert-consensus, the agreement of non-expert observers in assessing physiological pattern of disease (focal or diffuse) ranged from 69.1 to 85.0% (p for heterogeneity < 0.0001). There was no evidence for a moderating effect of years of experience; the pooled accuracy of middle-level doctors was 78.8% (95% confidential interval [CI] 72.8-84.7%) vs. 79.1% for junior-level doctors (95% CI 75.9-82.2%, p = 0.95 for difference). On the other hand, we observed a significant moderating effect of center volume. Accuracy across non-experts in high-volume centers was 82.7% (95% CI 80.3-85.1%) vs. 75.1% for low-volume centers (95% CI 71.9-78.3%, p = 0.0002 for difference). Interpretation of PW-pullback by non-expert interventional cardiologists was considerably subjective.

The center volume–outcome effect in pancreas transplantation: a national analysis

BackgroundAlthough increased hospital volume has been correlated with improved outcomes in certain surgical procedures, the effect of center volume on pancreas transplantation (PT) is less understood. Our study aims to establish whether a volume-outcome effect exists for PT. MethodsThrough an established linkage between the University HealthSystem Consortium and the Scientific Registry of Transplant Recipients (SRTR) databases, we performed a retrospective cohort analysis of adult PT recipients between 2009 and 2012. Surgical volume was divided equally into low volume (LV), middle volume (MV), and high volume (HV) tertiles for each year that was studied. Hospital outcomes were measured through University HealthSystem Consortium, and long-term outcomes were measured through Scientific Registry of Transplant Recipients. Statistical analysis was performed using regression analyses and the Kaplan-Meier method. Median follow-up period was 2 y. ResultsAmong the 2309 PT recipients included, 815 (35.3%) were performed at LV centers, 755 (32.7%) at MV centers, and 739 (32.0%) at HV centers. Compared with MV and LV centers, organs transplanted at HV centers were more frequently donation after cardiac death (5.1% versus 2.4% versus 3.3%, P = 0.01) and from older donors (2.8% [>50 y] versus 0.8% versus 0.1%, P < 0.001). In addition, HV recipients were older (31.5% [>50 y] versus 20.9% versus 19.7%, P < 0.001) and had worse functional status (39.5% dependent versus 9.7% versus 9.9%, P < 0.001). Patient and graft survival were similar across hospital volume tertiles. Center volume was not predictive of readmission rates, total length of stay, intensive care unit length of stay, or total direct cost on multivariate analysis (all P > 0.05). ConclusionsShort- and long-term outcomes after PT are not affected by hospital volume. Although LV centers confine their cases to low-risk patients, HV centers transplant a higher percentage of high-risk donor and recipient combinations with equivalent outcomes.

Effect of Center Volume on Outcomes in Hospitalized Patients With Hereditary Hemorrhagic Telangiectasia

ObjectiveTo determine whether hospitalized patients with hereditary hemorrhagic telangiectasia (HHT) had better outcomes at high-volume treatment centers (HVCs). Patients and MethodsThe Nationwide Inpatient Sample (2000-2011) was used to identify HHT-related hospitalizations. Hospitals were classified based on quartiles of annual HHT discharge volume. The 75th percentile cutoff value (third quartile) was used to classify hospitals as low-volume centers (1-7 HHT discharges per year) or as HVCs (≥8 discharges per year. Demographic features, complication rates, and outcomes were compared between the 2 groups. ResultsWe identified 9440 hospital discharges in patients with HHT. Of these patients, 6856 (72.6%) were admitted to low-volume centers and 2584 (27.4%) to HVCs. The former were more likely to be of white race, older, and with higher income levels (P<.001 for each). The HVCs had higher rates of anemia, epistaxis, congestive heart failure, pulmonary hypertension, and cerebral and pulmonary arteriovenous malformations and lower rates of ischemic stroke and myocardial infarction. After adjusting for baseline differences in a multivariate model, patients treated at HVCs were more likely to be discharged home (odds ratio [OR]=1.35; 95% CI, 1.21-1.52; P<.001) and less likely to be discharged to short-term rehabilitation facilities (OR=0.45; 95% CI, 0.31-0.64; P<.001). Patients treated at HVCs also had a significantly lower risk of in-hospital mortality (OR=0.51; 95% CI, 0.34-0.74; P<.001). ConclusionPatients with HHT hospitalized at HVCs had better outcomes, with lower in-hospital mortality and higher home discharge rates. These findings strongly support ongoing efforts to expand access to HHT centers of excellence in the United States and worldwide.

Effect of Transplant Center Volume on Cost and Readmissions in Medicare Lung Transplant Recipients.

Although lung transplant recipient survival is better at higher volume centers, the effect of center volume on admission cost and early hospital readmission is unknown. To understand the association between transplant center volume and recipient risk-adjusted transplant admission cost, in-hospital mortality, and early hospital readmission in lung transplant recipients. Medicare lung transplant recipients from May 4, 2005 to December 31, 2011 were identified through linkage of transplant registry and Medicare administrative claims. Transplant admission cost was extracted, adjusted for regional price variation, and compared across low-, intermediate-, and high-volume centers. A multivariable hierarchical generalized linear regression model was used to assess the effect of transplant center volume on recipient adjusted cost. Modified Poisson regression models were used to assess adjusted in-hospital mortality and early hospital readmission by transplant center volume. There were 3,128 Medicare lung transplant recipients identified. Unadjusted transplant cost was lower at high-volume centers (mean, $131,352 [SD, ±$106,165]; median, $90,177; interquartile range [IQR], $79,165-$137,915) than at intermediate-volume (mean, $138,792 [SD, ±$106,270]; median, $93,024; IQR, $82,700-$154,857) or low-volume (mean, $143,609 [SD, ±$123,316]; median, $95,234; IQR, $83,052-$152,149) centers (P < 0.0001). After adjusting for recipient health risk, low-volume centers had an 11.66% greater transplant admission cost (P = 0.040), a 41% greater risk for in-hospital mortality (P = 0.015), and a 14% greater risk for early hospital readmission (P = 0.033) compared with high-volume centers. There was no significant difference in transplant cost, in-hospital mortality, or early hospital readmission between intermediate- and high-volume centers. Lung transplant admission cost, in-hospital mortality, and early hospital readmission rate are lower at high-volume centers compared with low-volume centers.

HIGH CENTER VOLUME IS ASSOCIATED WITH LOWER IN-HOSPITAL MORTALITY IN HEART FAILURE PATIENTS: A NEW YORK STATE WIDE ANALYSIS OF 300,000 ADMISSIONS

Center volume is a determinant of outcomes in patients requiring complex medical treatments. We evaluated the effect of center volume on in-hospital mortality in patients with a primary discharge diagnosis of heart failure (HF). A retrospective analysis of adult patients with a primary discharge

The Effect of Center Volume on In-Hospital Mortality After Aortic and Mitral Valve Surgical Procedures: A Population-Based Study

We aimed to determine the relationship between hospital volume and use of dual aortic and mitral valve surgical procedures. Patients who underwent both aortic and mitral valve repair or replacement during the same hospital stay were identified from the Nationwide Inpatient Sample (NIS). We compared patients' characteristics and in-hospital outcomes by the average annual center volume for multiple-heart valve surgical procedures, grouped into tertiles of patients with low (1 to 8), medium (9 to 18), and high (19+) volume categories using χ(2) tests and adjusted hierarchical logistic regression models. From 1998 to 2011 an estimated total of 87,675 patients underwent combined aortic and mitral valve surgical procedures across the United States. Although most patients' characteristics were similar across volume groups, high-volume centers were more likely to treat older patients with coronary artery disease and to perform concomitant tricuspid valve operations. Low-volume centers replaced the aortic and mitral valves concomitantly more frequently with mechanical valves compared with high-volume centers (66.1% vs 45.5%), and this difference persisted across age groups. Compared with low-volume centers, the risk-adjusted odds ratios for in-hospital mortality at medium- and high-volume centers were 0.85 (95% confidence interval [CI]: 0.74 to 0.99) and 0.66 (95% CI: 0.55 to 0.80), respectively. No significant interaction was found between overall facility major cardiac surgery volume and multiple-valve procedure volume with respect to mortality (p = 0.143). Hospital volume remains an important factor influencing risk-adjusted mortality after combined aortic and mitral valve surgical procedures. Hospitals that perform more than eight combined aortic and mitral heart valve operations demonstrate a superior statistical hospital survival compared with those that perform less than eight multiple-heart valve operations a year. Further policy interventions aimed to lower hospital mortality in low-volume centers may offer possibilities for quality improvement in the field of valve surgery.

(687) - Effect of Center Volume on Survival After Lung Re-Transplantation

(687) - Effect of Center Volume on Survival After Lung Re-Transplantation

Survival in pediatric lung transplantation: The effect of center volume and expertise

Institutional operative volume has been shown to impact outcomes of various procedures including lung transplantation (LTx). We sought to determine whether this holds true with pediatric LTx by comparing outcomes of adult centers (with larger overall volume) to those of pediatric centers (with smaller volume but more pediatric-specific experience). A retrospective analysis of the Organ Procurement and Transplant Network data was performed. Centers were categorized as either adult (LTx volume predominantly in adult patients), high-volume pediatric (HVP, ≥4 LTxs/year), or low-volume pediatric (LVP, <4 LTxs/year). Outcomes were compared in "younger children" (<12 years) and "older children and adolescents" (12 to 17 years). In total, 1,046 pediatric LTxs were performed between 1987 and 2012 at 62 centers (adult 51 [82%], HVP 3 [5%], LVP 8 [13%]). Although adult centers had larger overall LTx volume, their pediatric experiences were severely limited (median 1/year). In younger children, HVP centers were significantly better than LVP centers for patient survival (half-life: 7.3 vs 2.9 years, p = 0.002). Similarly, in older children and adolescents, HVP centers were significantly better than adult centers for patient survival (half-life: 4.6 vs 2.5 years, p = 0.001). Of note, even LVP centers tended to have longer patient survival than adult centers (p = 0.064). Multivariable analysis identified adult centers as an independent risk factor for graft failure (hazard ratio: 1.5, p < 0.001) as with LVP (hazard ratio: 1.3, p = 0.0078). Despite larger overall clinical volume, outcomes among pediatric LTx recipients in adult centers are not superior to those of pediatric centers. Not only center volume but pediatric-specific experience has an impact on outcomes in pediatric LTx.

Center Volume Impacts Survival in Pediatric Lung Transplantation

<h3>Purpose</h3> The effect of center volume on adult lung transplantation (LTx) survival has been reported. Although other institutional and patient factors play a role in determining the overall survival rates, the center volume as a surrogate of experience has also been shown to directly impact the outcomes of LTx. However, this effect has not been demonstrated for pediatric LTx. The purpose of this study was to analyze the effect of center volume on pediatric LTx using a national database. <h3>Methods and Materials</h3> Query of United Network of Organ Sharing database through 06/2012 yielded 1044 pediatric (≤18y) LTx. Multiorgan Tx were excluded. The effect of center volume was analyzed as cumulative experience and yearly median number of LTx, and divided into high and low volume centers ensuring equal division of LTx in both groups. For excluding the era-effect, a sub-analysis of LTx was also performed (2000-2012). Cox-regression was used to calculate the risk of failure related to center volume. <h3>Results</h3> The graft and patient LTx survival was better in high-volume centers (3 centers, 517 LTx) than the low-volume centers (59 centers, 527 LTx) (p<0.006) (figure). The 1y-conditional graft and patient survival was also better for high-volume centers (p<0.001). Sub-analysis of the recent era showed a better graft (p=0.008) and patient (p=0.006) survival for high-volume centers. The yearly median LTx cut-off for improved survival was 4 LTx/year. There was a 40% increased risk of LTx graft failure for low-volume centers (p=0.022). <h3>Conclusions</h3> Center volume has an impact on patient and graft survival in pediatric lung transplantation. Further detailed risk-factor analysis will help in determining the extent of this impact.

Abstract 6: Relationship between Center-Volume and Complication Rates in the Carotid Revascularization Endarterectomy versus Stenting Trial

Background There is evidence that center-volume of cases affects outcomes for both carotid endarterectomy (CEA) and stenting (CAS). We sought to evaluate the effect of center-volume by site on complication rates in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST). Methods In CREST, the primary composite endpoint was any stroke, myocardial infarction, or death within 30 days or ipsilateral stroke in follow-up. Certification was achieved by 477 surgeons performing more than 12 procedures per year with complication rates less than 3% for asymptomatic patients and less than 5% for symptomatic patients; 224 interventionists were certified after a rigorous training and credentialing process that included a lead-in registry. CREST centers were divided into tertiles based on the number of patients enrolled into the study, with Group 1 composed of 82 sites each enrolling &lt;25 patients, Group 2 with 24 sites enrolling 25-51 patients and Group 3 with 10 sites enrolling &gt;51 patients. Differences in periprocedural event rates for the primary composite endpoint and its components were compared using logistic regression adjusting for age, sex, and symptomatic status within site-volume level. Results The safety of CAS and CEA did not vary by site-volume during the periprocedural period as indicated by occurrence of the primary endpoint (p=0.54) or by stroke and death (p=0.87). Conclusion Complication rates (as indicated by the primary endpoint and its components) were low in CREST and were not associated with center-volume. The data are consistent with the value of rigorous training and credentialing in trials evaluating endovascular devices and surgical procedures; because of ongoing entry of new interventionalists and surgeons into CREST, operator experience independent of center-volume cannot be addressed.

296: The Effect of Center Volume on Early Post Lung Transplantation Survival among Patients with Cystic Fibrosis

Caseload is associated with improved patient outcomes for many surgical procedures. Cystic fibrosis (CF) is a multi-system disease with unique post-operative challenges, and little is known about the effect of center experience on post-transplant CF outcomes. The purpose of this study is to determine whether center volume affects survival after lung transplantation in CF.

Hepatic Artery Thrombosis After Adult Living Donor Liver Transplantation: The Effect of Center Volume

To investigate whether center volume impacts the rate hepatic artery thrombosis (HAT) and patient survival after adult living donor liver transplantation (ALDLT). Patients with HAT who were listed as Status 1 in the Organ Procurement Transplant Network database were included in the study. Recipients of ALDLT were compared to those who received a deceased donor liver transplant (DDLT). Recipients of ALDLT had a higher rate of HAT than recipients of DDLT. Centers that performed less than four adult ALDLT had a higher rate of HAT than other higher volume centers. "Novice" centers had a worse graft and patient survival than those with more experience in ALDLT. Recipients who had HAT experienced a worse patient survival than those who did not. Centers with higher volume have a lower rate of HAT and a better patient and graft survival in ALDLT. Clearer regulations and focus on overcoming the learning curve might be needed to increase the utilization of ALDLT.

Assessing the validity of the endoscopic shunt insertion trial: did surgical experience affect the results?

Most surgical procedures are associated with a learning curve in which the success rate is lower early in the experience before mistakes have been identified and modifications made to the procedure. Negative results obtained early in a trial's learning curve may be a matter of timing rather than a reflection of the procedure's effectiveness. The recently published results of the Endoscopic Shunt Insertion Trial (ESIT) represent the notion that endoscopically placed shunts were no more likely to survive than conventionally placed shunts. This negative result may be due to inexperience in performing endoscopic surgeries. . Surgical experience was assessed in two ways. Shunt survival rates were compared between cases treated endoscopically in the 1st and last years of the ESIT. The effect of center volume was evaluated using a Cox proportional hazard model in which the following variables were analyzed: age at registration, the diagnosis of myelomeningocele, head size, method of shunt placement (endoscopic compared with conventional), and center volume. There was no difference in survival (endurance) of the shunt between patients enrolled in the 1st and last years (log rank = 0.08, p = 0.77). Likewise, no variable in the Cox multivariate model, including center volume, was a significant factor in predicting shunt survival. The primary result of the ESIT was found to be internally valid. The fact that endoscopic shunt placement did not benefit patients evaluated in the study was not due to early timing of the trial. Any learning curve among the participating surgeons did not adversely affect the results.

The effect of center volume on pancreas transplant outcomes

BackgroundCaseload often correlates with improved outcomes for several surgical procedures, including solid organ transplantation. Given the unique nature of pancreas transplantation and large variation in transplant center volumes, this study aims to determine whether center volume affects patient and graft survival after pancreas transplantation. MethodsRegistry data on all forms of whole organ pancreas transplants performed between 1995 and 2000 were obtained from the United Network for Organ Sharing. Patient and graft survival rates were followed until 2002. Center volume then was categorized as: low (<10/year), medium (10-20/year), high (21-50/year), and very high (<50/year). Cox proportional hazard regression models were developed to evaluate factors affecting pancreas transplant outcomes. ResultsVery-high-volume centers were more likely to do pancreas after kidney transplant, pancreas transplant alone, pancreas with kidney transplant, and repeat transplants, while other centers more frequently performed simultaneous pancreas-kidney transplants (P < .001). Very-high-volume centers were more likely to transplant older recipients and less likely to transplant minority or Medicaid patients. Low-volume centers tended to accept pancreatic allografts from younger donors and had the longest waiting times. In models adjusting for differences in patient population, there were no differences in patient survival. However, low-volume centers had a slightly increased risk of graft loss compared to other centers. Early graft loss was similar among all centers, but medium-volume centers were at increased risk for late graft loss. ConclusionsLow center volume is not associated with increased mortality after pancreas transplantation. Other factors appear to be more important than center volume in determining pancreas transplant outcomes.

Effect of center volume on outcome of ventricular septal defect closure and arterial switch operation

This study evaluates the effects of surgical volume and preoperative patient characteristics on length of stay following ventricular septal defect (VSD) repair and arterial switch operation (ASO). Twenty-four centers contributed data on 16,795 consecutive surgical procedures from January 1, 1992 to December 31, 1996 to the Pediatric Cardiac Care Consortium Registry. The following variables were used in the analysis: center, center volume, age, weight, date of operation, preoperative hospital days, presence of trisomy 21, and significant coexisting heart defects (risk). For VSD, all variables were associated with length of stay in the univariate analyses; however, in the multivariate model, center volume did not retain significance. Length of stay for ASO was associated with center, center volume, and preoperative days in the univariate analysis. In the multivariate analysis for ASO, center and center volume were significant variables for predicting length of stay. These findings suggest that length of stay for uncomplicated surgical procedures is not related to surgical volume; however, for technically demanding procedures, length of stay tends to be shorter in centers with more experience.