Total Center Percutaneous Coronary Intervention Volume and 30-Day Mortality: A Contemporary National Cohort Study of 427 467 Elective, Urgent, and Emergency Cases

Volume-Outcome Relationships for Intra-Aortic Balloon Pump in Acute Myocardial Infarction

BACKGROUND

Acute myocardial infarction (AMI) is a major scenario for the use of an intra-aortic balloon pump (IABP), particularly when complicated by cardiogenic shock, although the utilization of mechanical circulatory support devices varies widely per hospital. We evaluated the relationship, at the hospital level, between the volume of IABP use and mortality in AMI.

METHODS AND RESULTS

Using a Japanese nationwide administrative database, 26,490 patients with AMI undergoing primary percutaneous coronary intervention (PCI) from 154 hospitals were included in this study. The primary endpoint was the observed-to-predicted in-hospital mortality ratio. Predicted mortality per patient was calculated using baseline variables and averaged for each hospital. The associations among PCI volume for AMI, observed and predicted in-hospital mortality, and observed and predicted IABP use were assessed per hospital. Of 26,490 patients, 2,959 (11.2%) were treated with IABP and 1,283 (4.8%) died during hospitalization. The annualized number of uses of IABP per hospital in AMI was 4.5. In lower-volume primary PCI centers, IABP was more likely to be underused than expected, and the observed-to-predicted in-hospital mortality ratio was higher than in higher-volume centers.

CONCLUSIONS

A lower annual number of IABP use was associated with an increased mortality risk at the hospital level, suggesting that IABP use can be an institutional quality indicator in the setting of AMI.

Volume-outcome relationships for extracorporeal membrane oxygenation in acute myocardial infarction

Acute myocardial infarction (MI) is one of the major scenarios of extracorporeal membrane oxygenation (ECMO) use. The utilization of mechanical circulatory support systems including ECMO varies widely at the hospital level, while whether ECMO volume per hospital is associated with outcomes in acute MI is unclear. Using a Japanese nationwide administrative database, a total of 26,913 patients with acute MI undergoing percutaneous coronary intervention from 154 hospitals were included. The relations among PCI volume for acute MI, observed and predicted in-hospital mortality, and observed and predicted rates of ECMO use were evaluated at the hospital level. Of 26,913 patients, 423 (1.6%) were treated with ECMO, and 1561 (5.8%) died during the hospitalization. Median ECMO use per hospital per year was 0.5. An observed rate of ECMO use was linearly correlated with the predicted probability of ECMO use and was not associated with the observed/predicted in-hospital mortality ratio. The observed/predicted mortality ratio was lowest in hospitals with the observed/predicted ECMO use ratio of around one. In conclusion, ECMO was infrequently used in a setting of acute MI at each hospital annually. An observed rate of ECMO use was not associated with observed/predicted in-hospital mortality ratio, while the observed/predicted in-hospital mortality ratio was lowest when ECMO was used as predicted, suggesting that standardized ECMO use may be an institutional quality indicator in acute MI.

Center Volumes Correlate with Likelihood of Stent Implantation in German Coronary Angiography

Aims

Literature on percutaneous coronary intervention (PCI) stated an inverse relationship between hospital volume and mortality, but the effects on other characteristics are unclear.

Methods

Using German national records, all coronary angiographies with coronary artery disease in 2017 were identified. We applied risk-adjustment to account for differences in population characteristics.

Results

Of overall 528,188 patients, 55.22% received at least one stent, with on average 1.01 stents implanted in all patients. Based on those patients who received at least one stent, this corresponds to an average number of 1.82 stents. In-hospital mortality across all patients was 2.93%, length of hospital stay was 6.46 days, and mean reimbursement was €5,531. There were comparatively more emergency admissions in low volume centers and more complex cases (3-vessel disease, left main stenosis, and in-stent stenosis) in high volume centers. In multivariable regression analysis, volume and likelihood of stent implantation (p=0.003) as well as number of stents (p=0.020) were positively correlated. No relationship was seen for in-hospital mortality (p=0.105), length of stay (p=0.201), and reimbursement (p=0.108). Nonlinear influence of volume suggests a ceiling effect: In hospitals with ≤100 interventions, likelihood and number of implanted stents are lowest (∼34% and 0.6). After that, both rise steadily until a volume of 500 interventions. Finally, both remain stable in the categories of over 500 interventions (∼60% and 1.1).

Conclusion

In PCI, lower volume centers contribute to emergency care. Higher volume centers treat more complex cases and show a higher likelihood of stent implantations, with a stable safety.

Volume-outcome relationship in complication-related mortality after percutaneous coronary interventions: an analysis on the failure-to-rescue rate in the Japanese Nationwide Registry

In-hospital mortality following percutaneous coronary intervention (PCI) varies across institutions with different annual PCI volumes. The failure to rescue (FTR) rate, defined as the mortality rate following PCI-related complications, may account for the volume-outcome relationship. The Japanese Nationwide PCI Registry, a consecutive, nationally mandated registry between 2019 and 2020, was queried. The FTR rate is defined as 'the number of patients who died following PCI-related complications' divided by 'the number of patients who experienced at least one PCI-related complication.' Multivariate analysis was used to calculate the risk-adjusted odds ratio (aOR) of the FTR rates among hospitals stratified into tertiles as low (≤ 236/year), medium (237-405/year), and high (≥ 406/year). A total of 465,716 PCIs and 1007 institutions were included. A volume-outcome relationship was observed for in-hospital mortality, and the medium-volume (aOR 0.90, 95% confidence interval [CI] 0.85-0.96), as well as high-volume (aOR 0.84, 95% CI 0.79-0.89) hospitals, had significantly lower in-hospital mortality than low-volume hospitals. Complication rates were lower at high-volume centers (1.9%, 2.2%, and 2.6% for high-, medium-, and low-volume centers, respectively; p < 0.001). The overall FTR rate was 19.0%. The FTR rates for the low-, medium-, and high-volume hospitals were 19.3%, 17.7%, and 20.6%, respectively. The medium-volume hospitals had a lower FTR rate (aOR 0.82, 95% [CI] 0.68-0.99), whereas the FTR rate was similar at the high-volume hospitals compared with that of the low-volume hospitals (aOR 1.02, 95% CI 0.83-1.26). In-hospital mortality was low after PCI in high-volume hospitals. However, the FTR rate in high-volume hospitals was not necessarily lower than that in low-volume hospitals. The FTR rate did not account for the volume-outcome relationship in PCI.

Association between operator volume and mortality in primary percutaneous coronary intervention

Background

There is a paucity of real-world data assessing the association of operator volumes and mortality specific to primary percutaneous coronary intervention (PPCI).

Methods

Demographic, clinical and outcome data for all patients undergoing PPCI in Leeds General Infirmary, UK, between 1 January 2009 and 31 December 2011, and 1 January 2013 and 31 December 2013, were obtained prospectively. Operator volumes were analysed according to annual operator PPCI volume (low volume: 1–54 PPCI per year; intermediate volume: 55–109 PPCI per year; high volume: ≥110 PPCI per year). Cox proportional hazards regression analyses were undertaken to investigate 30-day and 12-month all-cause mortality, adjusting for confounding factors.

Results

During this period, 4056 patients underwent PPCI, 3703 (91.3%) of whom were followed up for a minimum of 12 months. PPCI by low-volume operators was associated with significantly higher adjusted 30-day mortality (HR 1.48 (95% CI 1.05 to 2.08); p=0.02) compared with PPCI performed by high-volume operators, with no significant difference in adjusted 12-month mortality (HR 1.26 (95% CI 0.96 to 1.65); p=0.09). Comparisons between low-volume and intermediate-volume operators, and between intermediate and high-volume operators, showed no significant differences in 30-day and 12-month mortality.

Conclusions

Low operator volume is independently associated with higher probability of 30-day mortality compared with high operator volume, suggesting a volume–outcome relationship in PPCI at a threshold higher than current recommendations.

Annual operator volume among patients treated using percutaneous coronary interventions with rotational atherectomy and procedural outcomes: Analysis based on a large national registry

BACKGROUND

Low operator and institutional volume are associated with poorer procedural and long-term clinical outcomes in the general population of patients treated with percutaneous coronary interventions (PCI).

AIM

To assess the relationship between operator experience and procedural outcomes of patients treated with PCI and rotational atherectomy (RA).

METHODS

Data for conducting the current analysis were obtained from the national registry of percutaneous coronary interventions (ORPKI) maintained in cooperation with the Association of Cardiovascular Interventions (AISN) of the Polish Cardiac Society. The study covers data from January 2014 to December 2020.

RESULTS

During the investigated period, there were 162 active CathLabs, at which 747,033 PCI procedures were performed by 851 operators (377 RA operators [44.3%]). Of those, 5188 were PCI with RA procedures; average 30 ± 61 per site/7 years (Me: 3; Q1-Q3: 0-31); 6 ± 18 per operator/7 years (Me: 0; Q1-Q3: 0-3). Considering the number of RA procedures annually performed by individual operators during the analyzed 7 years, the first quartile totaled (Q1: < =2.57), the second (Q2: < =5.57), and the third (Q3: < =11.57), while the fourth quartile was (Q4: > 11.57). The maximum number of procedures was 39.86 annually per operator. We demonstrated, through a nonlinear relationship with annualized operator volume and risk-adjusted, that operators performing more PCI with RA per year (fourth quartile) have a lower number of the overall periprocedural complications (p = 0.019).

CONCLUSIONS

High-volume RA operators are related to lower overall periprocedural complication occurrence in patients treated with RA in comparison to low-volume operators.

Volume-Outcome Relationships for Percutaneous Coronary Intervention in Acute Myocardial Infarction

Background Lower primary percutaneous coronary intervention (PCI) volume is known to be associated with worse outcomes in patients with acute myocardial infarction (MI) at hospital level. The present study aimed to evaluate the relations of primary, elective, and total PCI volume and primary/total PCI volume ratio per hospital to in-hospital mortality in patients with acute MI undergoing primary PCI. Methods and Results Using a large nationwide administrative database, we included a total of 83 076 patients from 154 hospitals in Japan undergoing PCI for either acute MI or elective cases. Relations of annual procedural volumes for primary, elective, and total PCI to in-hospital mortality after acute MI at hospital level were evaluated. The ratio of primary to total PCI volume per hospital was also assessed. The primary end point was the ratio of observed to predicted mortality. Of 83 076 patients, 26 913 (32.4%) underwent primary PCI for acute MI, among whom 1561 (5.8%) died during hospitalization. Overall, observed in-hospital mortality after acute MI and observed/predicted mortality ratio were higher in hospitals with lower primary, elective, and total PCI volumes. Observed/predicted in-hospital mortality ratio was higher in hospitals with low primary/total PCI volume ratio, even in those with high total PCI volume. Conclusions Primary, elective, and total PCI volume at hospitals were inversely associated with in-hospital mortality in patients with acute MI undergoing primary PCI. Lower ratio of primary to total PCI volume were related to higher in-hospital mortality, suggesting primary/total PCI volume ratio as an institutional indicator of quality of care for acute MI.

Risk prediction in multicentre studies when there is confounding by cluster or informative cluster size

Background

Clustered data arise in research when patients are clustered within larger units. Generalised Estimating Equations (GEE) and Generalised Linear Models (GLMM) can be used to provide marginal and cluster-specific inference and predictions, respectively.

Methods

Confounding by Cluster (CBC) and Informative cluster size (ICS) are two complications that may arise when modelling clustered data. CBC can arise when the distribution of a predictor variable (termed ‘exposure’), varies between clusters causing confounding of the exposure-outcome relationship. ICS means that the cluster size conditional on covariates is not independent of the outcome. In both situations, standard GEE and GLMM may provide biased or misleading inference, and modifications have been proposed. However, both CBC and ICS are routinely overlooked in the context of risk prediction, and their impact on the predictive ability of the models has been little explored. We study the effect of CBC and ICS on the predictive ability of risk models for binary outcomes when GEE and GLMM are used. We examine whether two simple approaches to handle CBC and ICS, which involve adjusting for the cluster mean of the exposure and the cluster size, respectively, can improve the accuracy of predictions.

Results

Both CBC and ICS can be viewed as violations of the assumptions in the standard GLMM; the random effects are correlated with exposure for CBC and cluster size for ICS. Based on these principles, we simulated data subject to CBC/ICS. The simulation studies suggested that the predictive ability of models derived from using standard GLMM and GEE ignoring CBC/ICS was affected. Marginal predictions were found to be mis-calibrated. Adjusting for the cluster-mean of the exposure or the cluster size improved calibration, discrimination and the overall predictive accuracy of marginal predictions, by explaining part of the between cluster variability. The presence of CBC/ICS did not affect the accuracy of conditional predictions. We illustrate these concepts using real data from a multicentre study with potential CBC.

Conclusion

Ignoring CBC and ICS when developing prediction models for clustered data can affect the accuracy of marginal predictions. Adjusting for the cluster mean of the exposure or the cluster size can improve the predictive accuracy of marginal predictions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01321-x.

The relationship between procedural volume and patient outcomes for percutaneous coronary interventions: a systematic review and meta-analysis

BACKGROUND

The relationship between procedural volume and outcomes for percutaneous coronary interventions (PCI) is contentious, with previous reviews suggesting an inverse volume-outcome relationship. The aim of this study was to systematically review contemporary evidence to re-examine this relationship.

METHODS

A systematic review and meta-analysis was undertaken to examine the relationship between PCI procedural volume (both at hospital- and operator-levels) and outcomes in adults. The primary outcome was mortality. The secondary outcomes were complications, healthcare utilisation and process outcomes. Searches were conducted from 1 January 2008 to 28 May 2019. Certainty of the evidence was assessed using 'Grading of Recommendations, Assessment, Development and Evaluations' (GRADE). Screening, data extraction, quality appraisal and GRADE assessments were conducted independently by two reviewers.

RESULTS

Of 1,154 unique records retrieved, 22 observational studies with 6,432,265 patients were included. No significant association was found between total PCI hospital volume and mortality (odds ratio [OR]: 0.84, 95% confidence interval [CI]: 0.69-1.03, I 2 = 86%). A temporal trend from significant to non-significant pooled effect estimates was observed. The pooled effect estimate for mortality was found to be significantly in favour of high-volume operators for total PCI procedures (OR: 0.77, 95% CI: 0.63-0.94, I 2 = 93%), and for high-volume hospitals for primary PCI procedures (OR: 0.77, 95% CI: 0.62-0.94, I 2 = 78%). Overall, GRADE certainty of evidence was 'very low'. There were mixed findings for secondary outcomes.

CONCLUSIONS

A volume-outcome relationship may exist in certain situations, although this relationship appears to be attenuating with time, and there is 'very low' certainty of evidence. While volume might be important, it should not be the only standard used to define an acceptable PCI service and a broader evaluation of quality metrics should be considered that encompass patient experience and clinical outcomes. Systematic review registration: PROSPERO, CRD42019125288.

Procedural Volume and Outcomes After Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction in Kerala, India: Report of the Cardiological Society of India-Kerala Primary Percutaneous Coronary Intervention Registry

Background

There are limited data to inform policy mandating primary percutaneous coronary intervention (PPCI) volume benchmarks for catheterization laboratories in low‐ and middle‐income countries.

Methods and Results

This prospective state‐wide registry included ST‐segment–elevation myocardial infarction patients with symptoms of <12 hours, or with ongoing ischemia at 12 to 24 hours, reperfused with PPCI. From June 2013 to March 2016, we recruited 5560 consecutive patients. We categorized hospitals on the basis of annual PPCI volumes into low, medium, and high volume (<100, 100–199, and ≥200 PPCIs per year, respectively). Kaplan‐Meier curves and Cox regression models were used to examine the association between PPCI volume and 1‐year mortality. Among 42 recruiting hospitals, there were 24 (57.2%) low‐volume, 8 (19%) medium‐volume, and 10 (23.8%) high‐volume hospitals. The median (25th–75th percentile) TIMI (Thrombolysis in Myocardial Infarction) ST‐segment–elevation myocardial infarction risk score was 3 (2–5). Cardiac arrest before admission occurred in 4.2%, 2.1%, and 2.9% of cases at low‐, medium‐, and high‐volume hospitals, respectively (P=0.02). Total ischemic time differed significantly among low‐volume (median [25th–75th percentile], 3.5 [2.4–5.5] hours), medium‐volume (median, 3.8 [25th–75th percentile, 2.58–6.05] hours), and high‐volume hospitals (median, 4.16 [25th–75th percentile 2.8–6.3] hours) (P=0.01). Vascular access was radial in 61.5%, 71.3%, and 63.2% of cases at low‐, medium‐, and high‐volume hospitals, respectively (P=0.01). The observed 1‐year mortality rate was 6.5%, 3.4%, and 8.6% at low‐, medium‐ and high‐volume hospitals, respectively (P<0.01), and the difference did not attenuate after multivariate adjustment (low versus medium: hazard ratio [95% CI], 1.80 [1.12–2.90]; high versus medium: hazard ratio [95% CI], 2.53 [1.78–3.58]) (P<0.01).

Conclusions

Low‐ and middle‐income countries, like India, may have a nonlinear relationship between institutional PPCI volume and outcomes, partly driven by procedural variations and inequalities in access to care.

Assessment of Equity in Access to Percutaneous Coronary Intervention (PCI) Centres in Poland

The purpose of this study is to analyse the disparities in the distribution of percutaneous coronary intervention (PCI) centres in Poland and the impact of eventual inequities on access to the invasive treatment of acute myocardial infarctions (AMI). To examine the distribution of PCI centres against population size and geographic size in Poland, the Gini coefficient calculated based on the Lorenz Curve was engaged. In addition, the regression function was employed to estimate the impact of distribution of PCI centres on access to invasive procedures (coronarographies and primary percutaneous coronary intervention). Data were collected from the public statistical system and Polish National Health Fund database for the year 2018. The relation and the level of equity was measured based on the aggregated data at a district (voivodeship) level. The results of the Gini coefficient analysis show that the distribution of invasive cardiology units measured against population size is more equitable than when measured against geographic size. In addition, the regression analysis shows the moderate size of the positive correlation between number of PCI centres per 100,000 population and the number of all categories of the invasive treatment of AMI per 100,000 population, and the lack of similar correlation in case of the number of PCI centres expressed per 1000 km2, which could be evidence of an insufficiency of PCI centres in areas where the concentration of PCI centres per 100,000 population is lower. The main implication for policy makers that results from this research is the need for a correction of PCI centres distribution per 100,000 inhabitants to ensure better access to invasive procedures.

Role of Hospital Volumes in Identifying Low-Performing and High-Performing Aortic and Mitral Valve Surgical Centers in the United States

Importance

Identifying high-performing surgical valve centers with the best surgical outcomes is challenging. Hospital surgical volume is a frequently used surrogate for outcomes. However, its ability to distinguish low-performing and high-performing hospitals remains unknown.

Objective

To examine the association of hospital procedure volume with hospital performance for aortic and mitral valve (MV) surgical procedures.

Design, Setting, and Participants

Within an all-payer nationally representative data set of inpatient hospitalizations, this study identified 682 unique hospitals performing surgical aortic valve replacement (SAVR) and MV replacement and repair with or without coronary artery bypass grafting (CABG) between 2007 and 2011. Procedural outcomes were further assessed for a 10-year period (2005-2014) to assess representativeness of study period.

Main Outcomes and Measures

In-hospital risk-standardized mortality rate (RSMR) calculated using hierarchical models and an empirical bayesian approach with volume-based shrinkage that allowed for reliability adjustment.

Results

At 682 US hospitals, 70 295 SAVR, 19 913 MV replacement, and 17 037 MV repair procedures were performed between 2007 and 2011, with a median annual volume of 43 (interquartile range [IQR], 23-76) SAVR, 13 (IQR, 6-22) MV replacement, and 9 (IQR, 4-19) MV repair procedures. Of 225 SAVR hospitals in the highest-volume tertile, 34.7% and 36.0% were in the highest-RSMR tertile for SAVR + CABG and isolated SAVR procedures, respectively, while 21.5% and 17.5% of the 228 SAVR hospitals in the lowest-volume tertile were in the lowest respective RSMR tertile. Similarly, 36.8% and 43.5% of hospitals in the highest tertile of volume for MV replacement and repair, respectively, were in the corresponding highest-RSMR tertile, and 17.4% and 11.2% of the low-volume hospitals were in the lowest-RSMR tertile for MV replacement and repair, respectively. There was limited correlation between outcomes for SAVR and MV procedures at an institution. If solely volume-based tertiles were used to categorize hospitals for quality, 44.7% of all valve hospitals would be misclassified (as either low performing or high performing) when assessing performance based on tertiles of RSMR.

Conclusions and Relevance

Hospital procedure volume alone frequently misclassifies hospital performance with regard to risk-standardized outcomes after aortic and MV surgical procedures. Valve surgery quality improvement endeavors should focus on a more comprehensive assessment that includes risk-adjusted outcomes rather than hospital volume alone.