Impact of hospital proportion and volume on primary percutaneous coronary intervention performance in England and Wales.

AIMS: To quantify the determinants of primary percutaneous coronary intervention (PCI) performance in England and Wales between 2004 and 2007. METHODS AND RESULTS: All 8653 primary PCI cases admitted to acute hospitals in England and Wales as recorded in the Myocardial Ischaemia National Audit Project (MINAP) 2004-2007. We studied the impact of the volume of primary PCI cases (hospital volume) on door-to-balloon (DTB) times and the proportion of patients treated with primary PCI (hospital proportion) on 30-day mortality and employed regression analysis to identify reasons for DTB time variations with a multilevel component to express hospital variation. The proportion of patients receiving primary PCI increased from 5% in 2004 to 20% in 2007. Median DTB times reduced from 84 min in 2004 to 61 min in 2007. Median DTB times decreased as the number of primary PCI procedures increased. The 30-day all-cause mortality rate for hospitals performing primary PCI on >25% of ST-elevation myocardial infarction patients [5.0%; 95% confidence interval (CI): 3.9-6.1%] was almost double that of hospitals performing primary PCI on more than 75% (2.7%; 95% CI: 2.0-3.5%). Time-of-day, year of admission, sex, and diabetes significantly influenced DTB times. Hospital variation was evident by a hospital-level DTB time standard deviation of 12 min. CONCLUSIONS: There was a large variation in DTB times between the best and worst performing hospitals. Although patient-related factors impacted upon DTB times, the volume and proportion of patients undergoing primary PCI were significantly associated with delay and early mortality-hospitals with the highest proportion of primary PCI had the lowest mortality.

Multiple imputation for completion of a national clinical audit dataset.

The Myocardial Ischaemia National Audit Project (MINAP) is a register of heart attacks covering 234 acute admitting hospitals in England and Wales. It is used to assess the extent to which hospitals are attaining the government targets for patients with heart attacks (myocardial infarction). MINAP is therefore of national importance in coronary care and of potential international importance for research. As with most observational databases, there is missing data in MINAP, which has the potential to bias statistical analyses. In this paper, we use multiple imputation to reduce the impact of missing data and we give details of how our imputation scheme was implemented. The key contribution of this paper is the provision of multiply completed datasets, suited to a range of analyses, that can be used to make efficient inferences without the distractions of missing data. Our work will assist MINAP in achieving its priority goal of providing useful data with which to analyse patient care.

Evaluation of the NICE mini-GRACE risk scores for acute myocardial infarction using the Myocardial Ischaemia National Audit Project (MINAP) 2003-2009: National Institute for Cardiovascular Outcomes Research (NICOR).

OBJECTIVE: To evaluate the performance of the National Institute for Health and Clinical Excellence (NICE) mini-Global Registry of Acute Coronary Events (GRACE) (MG) and adjusted mini-GRACE (AMG) risk scores. DESIGN: Retrospective observational study. SETTING: 215 acute hospitals in England and Wales. PATIENTS: 137 084 patients discharged from hospital with a diagnosis of acute myocardial infarction (AMI) between 2003 and 2009, as recorded in the Myocardial Ischaemia National Audit Project (MINAP). MAIN OUTCOME MEASURES: Model performance indices of calibration accuracy, discriminative and explanatory performance, including net reclassification index (NRI) and integrated discrimination improvement. RESULTS: Of 495 263 index patients hospitalised with AMI, there were 53 196 ST elevation myocardial infarction and 83 888 non-ST elevation myocardial infarction (NSTEMI) (27.7%) cases with complete data for all AMG variables. For AMI, AMG calibration was better than MG calibration (Hosmer-Lemeshow goodness of fit test: p=0.33 vs p<0.05). MG and AMG predictive accuracy and discriminative ability were good (Brier score: 0.10 vs 0.09; C statistic: 0.82 and 0.84, respectively). The NRI of AMG over MG was 8.1% (p<0.05). Model performance was reduced in patients with NSTEMI, chronic heart failure, chronic renal failure and in patients aged ≥85 years. CONCLUSIONS: The AMG and MG risk scores, utilised by NICE, demonstrated good performance across a range of indices using MINAP data, but performed less well in higher risk subgroups. Although indices were better for AMG, its application may be constrained by missing predictors.

An assessment of composite measures of hospital performance and associated mortality for patients with acute myocardial infarction. Analysis of individual hospital performance and outcome for the National Institute for Cardiovascular Outcomes Research (NICOR).

AIM: To investigate whether a hospital-specific opportunity-based composite score (OBCS) was associated with mortality in 136,392 patients with acute myocardial infarction (AMI) using data from the Myocardial Ischaemia National Audit Project (MINAP) 2008-2009. METHODS AND RESULTS: For 199 hospitals a multidimensional hospital OBCS was calculated on the number of times that aspirin, thienopyridine, angiotensin-converting enzyme inhibitor (ACEi), statin, ß-blocker, and referral for cardiac rehabilitation was given to individual patients, divided by the overall number of opportunities that hospitals had to give that care. OBCS and its six components were compared using funnel plots. Associations between OBCS performance and 30-day and 6-month all-cause mortality were quantified using mixed-effects regression analysis. Median hospital OBCS was 95.3% (range 75.8-100%). By OBCS, 24.1% of hospitals were below funnel plot 99.8% CI, compared to aspirin (11.1%), thienopyridine (15.1%), ß-blockers (14.7%), ACEi (19.1%), statins (12.1%), and cardiac rehabilitation (17.6%) on discharge. Mortality (95% CI) decreased with increasing hospital OBCS quartile at 30 days [Q1, 2.25% (2.07-2.43%) vs. Q4, 1.40% (1.25-1.56%)] and 6 months [Q1, 7.93% (7.61-8.25%) vs. Q4, 5.53% (5.22-5.83%)]. Hospital OBCS quartile was inversely associated with adjusted 30-day and 6-month mortality [OR (95% CI), 0.87 (0.80-0.94) and 0.92 (0.88-0.96), respectively] and persisted after adjustment for coronary artery catheterization [0.89 (0.82-0.96) and 0.95 (0.91-0.98), respectively]. CONCLUSIONS: Multidimensional hospital OBCS in AMI survivors are high, discriminate hospital performance more readily than single performance indicators, and significantly inversely predict early and longer-term mortality.