Between October 1, 2005 and September 30, 2007, at least one PCI occurred in a total of 29,784 admissions in Massachusetts licensed (non-Federal) hospitals. Among these admissions, 5,588 patients (18.8%) underwent a PCI after presenting with shock or ST segment elevation myocardial infarction (SOS cases). Within the SOS cohort of patients, a total of 96 patients (1.7% of SOS cases) were adjudicated as having qualified for compassionate use.
Compassionate use admissions were significantly more likely to have presented in cardiogenic shock (: 65.6% vs. 8.2%, p<0.001), more likely to have received an intra-aortic balloon pump (49.0% vs. 12.5%, p<0.001), and more likely to have pre-existing renal insufficiency on presentation (15.6% vs. 4.1%, p<0.001) as compared with SOS patients without compassionate use clinical features.
Patient presenting factors in the cardiogenic shock or ST segment myocardial infarction PCI cohort, overall and stratified by compassionate use.
In-hospital outcomes for compassionate use cases were dramatically worse than for the high risk SOS cohort of patients without compassionate use clinical features as a whole (). The likelihood of procedural success was significantly lower for CU cases as compared with non-CU SOS cases (79.2% vs. 94.2%, p<0.001). The CU cases were significantly more likely to suffer new post-procedural cardiogenic shock and more likely to experience bleeding and renal complications following the index procedure than non-CU cases. The unadjusted in-hospital mortality rate was 15.6 times higher for CU cases than for non CU SOS cases (69.8% vs. 4.5%, p<0.001). Although CU cases represented only 1.7% of overall SOS cases, these cases accounted for more than 21% of the overall mortality following PCI in the SOS cohort. Post-procedural death from neurologic causes was significantly more frequent in the compassionate use population as compared with the standard risk SOS cases, likely driven by the concentration of patients presenting with coma in the CU cohort. The observed mortality for CU cases with use of percutaneous ventricular support, rescucitation at the start of the procedure and coma on presentation were 50%, 84% and 70% respectively. Due to the relatively small individual sample sizes, there was no significant difference in the mortality rates between these three categories.
In-hospital complications and death, overall and stratified by compassionate use.
After adjusting for all other known predictors of in-hospital mortality, compassionate use designation was associated with an odds ratio for in-hospital death of 27.3 (95% CI:14.5–47.6) relative to the non-CU SOS patients. The final multiple logistic regression model included: patient age, pre-procedure renal insufficiency, documented pre-procedure left ventricular ejection fraction <30%, emergent or salvage procedure status, presence of left main coronary artery disease (of severity >50%), presentation with cardiogenic shock and the compassionate use indicator ().
Adjusted odds ratios of risk of in-hospital all-cause mortality following PCI in the Commonwealth of Massachusetts. Based on 5,588 PCI admissions from October 2005 through September 2007 and 312 deaths.
Among those CU patients who survived to hospital discharge, 83% (24 of 29) were alive at 30 days, while 76% (22 of 29) were alive at one year.
Inclusion of the compassionate use covariates significantly improved the inhospital mortality risk prediction model performance. The discrimination of the hierarchical mortality prediction model significantly improved from an ROC of 0.87 to 0.90 (p<0.001) with preserved goodness of fit. Individual cases were assigned to five risk strata according to predicted risk before and after incorporation of compassionate use criteria. Incorporation of the compassionate use covariate led to the reclassification of the risk by at least one risk strata for 347 SOS cases (6.2%). The NRI was 8.7% (p = 0.43), indicating that 8.7% more patients who died appropriately moved up a category of risk than down when compared with survivors. Most of the impact of inclusion of the new covariate was observed for those who died within the hospitalization ().
Impact of inclusion of compassionate use (CU) on predicted mortality
In this analysis, overall classification of hospital performance did not change significantly with the inclusion of the CU indicator variable (). However, there were measurable changes in the width and range of the estimated posterior intervals which made certain centers “closer” to a change in classification as an outlier institution. For example, the posterior interval for Hospital 1 was shifted to the left after including CU indicating a reclassification of cases which results in improved estimated quality relative to the overall State performance, as compared with the method that excluded the compassionate use indicator. In contrast, the posterior interval estimate for Hospital 12 was shifted to the right after inclusion of the CU indicator, indicating that reclassification of cases resulted in a less favorable estimate of risk adjusted mortality performance. Therefore, Hospital 12 was closer to being identified as an outlier for poorer performance after incorporation of CU indicators, than for the models that did not include CU. However, there were no changes in the posterior interval estimates that led to a change in overall classification by institution as either above, below or within expectations for risk adjusted mortality, though the observed changes in posterior intervals confirms the potential impact o inclusion of CU indicators on assessment of hospital quality.
Hospital risk adjusted mortality with and without compassionate use variable
While the impact on physician perception of the risk adjustment methods was not directly measured in this study, a temporal association was apparent after the introduction of the CU indicator in October 2005, with a substantial increase in the prevalence of cardiogenic shock among PCI admissions (). The proportion of overall PCI patients presenting in cardiogenic shock monotonically declined from 2.3% in 2003 to 1.3% in 2005. Beginning with the inclusion of compassionate use criteria in late 2005, this trend reversed with an increasing proportion of patients treated with PCI for cardiogenic shock for both 2006 and 2007, to a level of 1.7%. Of note, there was no concomitant change to the risk adjustment methodologies used for predicting mortality after coronary artery bypass graft (CABG) surgery, and the proportion of CABG cases with shock has declined steadily since the inception of public reporting of post-revascularization outcomes ().
Emergent revascularization for cardiogenic shock in MA, 2003–2007