Development of Comorbidity Index for in-hospital mortality for patients who underwent coronary artery revascularization

BACKGROUND

For myocardial revascularization, coronary artery bypass grafting (CAGB) and percutaneous coronary intervention (PCI) are two common modalities but with high in-hospital mortality. A Comorbidity Index is useful to predict mortality or can be used with other covariates to develop point-scoring systems. This study aimed to develop specific comorbidity indices for patients who underwent coronary artery revascularization.

METHODS

Patients who underwent CABG or PCI were identified in the National Inpatient Sample database between Q4 2015-2020. Patients of age <40 were excluded for congenital heart defects. Patients were randomly sampled into experimental (70%) and validation (30%) groups. Thirty-eight Elixhauser comorbidities were identified and included in multivariable regression to discriminate in-hospital mortality. Weight for each comorbidity was assigned and single indices, Li CABG Mortality Index (LCMI) and Li PCI Mortality Index (LPMI), were developed.

RESULTS

Mortality discrimination by LCMI approached adequacy (c-statistic=0.691, 95% CI=0.682-0.701) and was comparable to multivariable regression with comorbidities (c-statistic=0.685, 95% CI=0.675-0.694). LCMI discrimination performed significantly better than Elixhauser Comorbidity Index (ECI) (c-statistic=0.621, 95% CI=0.611-0.631) and can be further improved by adjusting age (c-statistic=0.721, 95% CI=0.712-0.730). All models were well-calibrated (Brier score=0.021-0.022). LPMI moderately discriminated in-hospital mortality (c-statistic=0.666, 95% CI=0.660-0.672) and performed significantly better than ECI (c-statistic=0.610, 95% CI=0.604-0.616). LPMI performed better than the all-comorbidity multivariable regression (c-statistic=0.658, 95% CI=0.652-0.663). After age adjustment, LPMI discrimination was significantly increased and was approaching adequacy (c-statistic=0.695, 95% CI=0.690-0.701). All models were well-calibrated (Brier score=0.025-0.026).

CONCLUSIONS

LCMI and LPMI effectively discriminated and predicted in-hospital mortality. These indices were validated and performed superior to ECI. These indices can standardize comorbidity measurement as alternatives to ECI to help replicate and compare results across studies.

Clinical and Administrative Data on the Research of Acute Coronary Syndrome in Spain. Minimum Basic Data Set Validity

INTRODUCTION AND OBJECTIVES

Health outcomes research is done from clinical registries or administrative databases. The aim of this work was to evaluate the concordance of the Minimum Basic Data Set (MBDS) with the DIOCLES (Descripción de la Cardiopatía Isquémica en el Territorio Español) registry and to analyze the implications of use of the MBDS in the study of acute coronary syndrome in Spain.

METHODS

Through indirect identifiers, DIOCLES was linked with MBDS and unique matches were selected. Some of most relevant variables for risk adjustment of in-hospital mortality due to acute myocardial infarction were considered. Kappa coefficient was used to evaluate the concordance; sensitivity, specificity and positive and negative predictive values to measure the validity of the MBDS, and the area under ROC (receiver operating characteristic) curve to calculate its discrimination. The results were compared among hospitals quintiles according to their contribution to DIOCLES. The influence of unmatched episodes on results was assessed by a sensitivity analysis, using looser linking criteria.

RESULTS

Overall, 1539 (60.85%) unique matches were achieved. The prevalence was higher in DIOCLES (acute myocardial infarction: 71.09%; Killip 3-4: 9.17%; cerebrovascular accident: 0.97%; thrombolysis: 8.64%; angioplasty: 61.92% and coronary bypass: 1.75%) than in the MBDS (P < .001). The agreement level observed was almost perfect (κ = 0.863). The MBDS showed a sensitivity of 85.10% and a specificity of 98.31%. Most results were confirmed by using sensitivity analysis (79.95% episodes matched).

CONCLUSIONS

The MBDS can be a useful tool for outcomes research of acute coronary syndrome in Spain. The contrast of DIOCLES and MBDS with medical records could verify their validity.

In-hospital mortality rates after CABG by autonomous regions in Spain

PURPOSE

The paper's purpose is twofold: to provide a predictive model for estimating in-hospital mortality rates after coronary artery bypass grafting (CABG) in Spanish autonomous regions (AR) after adjusting relevant factors; and to determine whether there is a difference between expected and observed mortality rates.

DESIGN/METHODOLOGY/APPROACH

All patients registered in a minimum basic data set (MSBD) undergoing CABG between 2000 and 2004 were selected. After bivariate analysis to explore associations between in-hospital death and other variables, a multivariate analysis using logistic regression was conducted. The predictive model was evaluated using calibration and discrimination techniques. Standardized mortality ratios by AR were calculated.

FINDINGS

The expected Spanish in-hospital mortality rate after CABG was 7.68 and the observed rate was 7.69 deaths per 100 operations. Discrimination obtained with the model resulted in an area under the curve of 0.70 (95 per cent CI, 0.69-0.71). When each AR's mortality rate is calculated and compared with the observed rate, some ARs present an observed mortality rate higher or lower than the expected rate according to adjusted variables in the model.

RESEARCH LIMITATIONS/IMPLICATIONS

The MSBD registry does not contain patients' critical data, such as arterial damage severity, or in which hospital procedures were performed.

PRACTICAL IMPLICATIONS

There are factors related to individual patient variation, financial resources or healthcare quality in different ARs, which should be investigated in follow-up studies.

ORIGINALITY/VALUE

The paper shows that, although the global expected mortality rate is almost the same as the observed Spanish mortality rate, this similarity disappears when AR rates are compared.

Survival, clinical status and quality of life five years after coronary surgery. The ARCA study

INTRODUCTION AND OBJECTIVES

Little is known about the long-term outcomes of coronary surgery and their determinants in Spain. The objectives of this study were to evaluate clinical outcomes, quality of life and survival in a cohort of patients 5 years after undergoing a first aortocoronary bypass operation without any other associated procedure.

METHODS

Patients who survived the operation and whose pre- and postoperative data had been collected prospectively were followed up by telephone interview after 5 years.

RESULTS

Information was available after 5 years on 1,300 (85.2%) of the 1,525 patients who survived until hospital discharge. Of these, 13.6% had died, while 24% had either died, undergone revascularization or were readmitted because of a cardiac complaint. The cumulative survival rate (excluding the period of hospitalization) was 0.87 (95% confidence interval, 0.85-0.89). Mortality varied significantly with the level of preoperative risk (i.e. the EuroSCORE), to the extent that mortality in the low-risk group was equivalent to that in the general reference population.

CONCLUSIONS

Three-quarters of patients who survived until hospital discharge after coronary surgery did not experience a major cardiac event within 5 years and their level of functioning and quality of life were good. The survival rate after the immediate postoperative period varied according to the patient's preoperative risk profile and, in low-risk patients, was equivalent to that in the general reference population.