AUCTORES
Research Article | DOI: https://doi.org/10.31579/2641-0419/253
1 Geisinger Heart Institute, Danville PA
2 Biostatistics Core Center for Health Research, Geisinger Health System, Danville PA
3 University of New Mexico, Albuquerque NM
*Corresponding Author: James C Blankenship, Division of Cardiology 1 University of New Mexico MC 10 5550 Albuquerque New Mexico.
Citation: Imran Baig, Amir Eslami DO, Andrea Berger MA, Cara Nordberg MPH, James Blankenship. (2022). Readmissions in the Year After Percutaneous Coronary Intervention. J. Clinical Cardiology and Cardiovascular Interventions, 5(4); Doi:10.31579/2641-0419/253
Copyright: © 2022 James C Blankenship, This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Received: 04 March 2022 | Accepted: 21 March 2022 | Published: 29 March 2022
Keywords: coronary artery disease; percutaneous coronary intervention; re-admission
Prior studies of readmission have evaluated correlates of 30-day readmission but have not evaluated correlates of readmission after 30 days. The study sought to evaluate factors associated with re-hospitalization within one year of undergoing percutaneous coronary intervention (PCI). We analyzed 6265 patients treated at Geisinger hospitals with PCI between January 2010 and December 2015. Correlates of readmission within 1 year were identified. Sub-groups were compared based on reason for readmission (related to versus not related to ischemic heart disease) and timing of readmission (1-30 days versus 31-365 days). Mean age was 64.3 years, 70% were male, and 98.8% were Caucasian. In the first year after PCI, 2,767 patients (44.2%) were re-admitted. Within 30 days 931 patients (14.9%) were readmitted; 1836 (29.3%) were readmitted between 31 and 365 days. Nine hundred fifty (15.2%). In summary, in an unselected patient cohort treated with PCI, approximately 44% of the patients were readmitted within one year. Two-thirds of these were admitted after the first month. Efforts to prevent the need for readmission should continue beyond the first month post-discharge and center on risk factor modification.
Ischemic heart disease related healthcare costs are amongst the highest for any disease entity in the United States. Approximately one in every six US health care dollars is spent on cardiovascular disease [1]. Hospital readmission rates are variable and add to the health care costs. With the high cost of ischemic heart disease and the additional cost of revascularization for this subset of patients, there is limited data on risk factors that correlate with readmission after percutaneous coronary intervention (PCI) [2-4]. Previous studies have reviewed 30-day readmissions post PCI. However, readmissions from 30 days to one-year post-PCI have received little attention. The purpose of this analysis was to identify patient and characteristics associated with hospital readmission in the year after PCI [5].
We studied 7,228 patients undergoing PCI at our medical center between January 1, 2010 and December 31, 2015. For patients with multiple PCI encounters during the study period only the first was included. Patients were excluded if they died during their hospital stay (n = 159), if the encounter was missing the admission and discharge date/time information due to PCI database and electronic health record (EHR) matching issues (n = 24), if they died within 365 days of their procedure without a readmission prior to death (n = 110), or if they were without follow-up in
the Geisinger Health System for 730 days after the original PCI discharge (n = 670). The remaining 6265 patients composed the study cohort.
Hospital readmissions (including emergency department visits and inpatient admissions) within 365 days of the PCI encounter discharge date were identified. Observation unit stays were excluded.
Descriptive statistics are provided for all 6265 patients, and for patients readmitted within 30 days, readmitted within 31-365 days, and not readmitted. Categorical variables are characterized using frequency counts and percentages. Continuous variables are characterized using means and standard deviations (S.D.) or medians and interquartile ranges (IQR). Characteristics of patients readmitted within 365 days were compared to those who were not readmitted using two-sample t-tests, Wilcoxon rank-sum tests, and Pearson’s chi-square, or Fisher’s exact tests, as appropriate. Multinomial logistic regression modeling was used to compare patients readmitted within 30 days, those readmitted within 31-365 days, and those that were not readmitted.
Due to the large number of study variables that were significantly associated with the readmission outcomes, bootstrap resampling was used for variable selection. Starting with 64 variables (Table 1), fast step-down selection keeping factors with significance levels < 0>
| Readmit vs Not Readmitted Model | 30 Day/31 to 365/Not Readmitted Model |
Age (Quadratic) | x | x |
Sex | x | |
Body Mass Index (Piecewise with knot at 30) | x | x |
Insurance Payers | x | x |
Current/Recent Smoker | x | |
Hypertension | x | x |
Dyslipidemia | ||
Family History of Premature coronary artery disease | ||
Prior myocardial infarction | x | |
Prior Heart Failure | x | x |
Prior Valve Surgery/Procedure | x | |
Prior percutaneous coronary intervention | ||
Prior Coronary artery bypass grafting | x | |
Currently on Dialysis | x | |
Cerebrovascular Disease | x | x |
Chronic Lung Disease | x | x |
Diabetes Mellitus | x | x |
Coronary artery disease Presentation | x | x |
Angina Classification within 2 Weeks | x | |
Heart Failure Within 2 Weeks | x | x |
Cardiomyopathy or LV Systolic Dysfunction | ||
Cardiogenic Shock Within 24 Hours | x | x |
Cardiac Arrest Within 24 Hours | ||
Fluoroscopy Time (Piecewise with knot at 19) | x | x |
Contrast Volume | ||
Procedure Diagnostic | x | x |
Intra-aortic balloon pump | ||
Arterial Access Site | x | x |
Left Main | ||
Proximal left anterior descending artery | ||
Distal left anterior descending artery | ||
Circumflex | ||
Right coronary artery | x | |
Ramus | ||
PCI Scheduling Status | x | x |
Cardiogenic Shock at Start of PCI | ||
Pre Creatinine (Piecewise with knot at 0.8) | x | x |
Pre Hemoglobin (Piecewise with knot at 15) | x | x |
Low Molecular Weight Heparin (any) | x | |
Unfractionated Heparin (any) at Procedure | ||
Aspirin at Procedure | ||
Bivalirudin at Procedure | x | |
Glycoprotein IIb/IIIa Inhibitors at Procedure | ||
Clopidogrel at Procedure | x | x |
Prasugrel at Procedure | ||
Ticagrelor at Procedure | x | x |
Angiotensin converting enzyme inhibitors/angiotensin receptor blockers s at Discharge | ||
Aspirin at Discharge | ||
Beta Blockers at Discharge | x | x |
Lipid-Lowering Agents (statins and non-statins) at Discharge | ||
Clopidogrel at Discharge | ||
Prasugrel at Discharge | x | x |
Ticagrelor at Discharge | x | x |
Culprit Lesion Identification | x | x |
Pre-Stenosis Percent | x | x |
Lesion Complexity | x | |
Length (mm) | ||
Thrombus | ||
Bifurcation | ||
Systolic Blood Pressure (Piecewise with knot at 120) | x | x |
Diastolic Blood Pressure (Piecewise with knot at 70) | x | |
Year of Intervention | x | x |
Charlson Comorbidity Index on procedure Date | x | x |
Duration of Index Hospitalization | x | x |
Table 1: Variables Used in Bootstrap Resampling for Variable Selection
not readmitted, and readmitted within 31-365 days vs. not readmitted. Variables selected in 50% or more of the 1000 repetitions for readmitted versus not readmitted were retained for a final multivariable logistic regression model. Variables retained in 50% or more of either the 30-day readmission versus not readmitted or 31-365-day readmission versus not readmitted model were retained for a final multivariable multinomial logistic regression model. Odds ratio estimates, 95% confidence intervals, and p-values are reported for the results of the multivariable models.
Restricted cubic splines were used to assess non-linear relationships between continuous variables and outcomes. Non-linear relationships were included in the multivariable models as quadratic terms or piecewise linear terms, as appropriate. Missingness in variables used in the variable selection process did not exceed 1.3% for categorical variables and 5.8% for continuous variables. Missing values for categorical variables were imputed by random assignment to a category proportional to the frequencies in the non-missing observations. Missing values for continuous variables were imputed using non-missing median values by sex. Analysis was performed using R version 3.5.0, and SAS 9.4.
The study cohort included 6265 patients. Mean age was 64.3 years, 70% were male, and 98.8% were Caucasian. In the first year after PCI, 2,767 patients (44.2%) were re-admitted. Nine hundred thirty-one patients (14.9%) were readmitted within 30 days and 1836 (29.3%) were readmitted between 31 and 365 days.
Correlates of Readmission within 365 days: Factors associated with readmission within a year are listed in Table 2 and results of multivariable logistic regression modeling are in Table 3. These included co-morbidities (Charlston comorbidity score, age, body mass index, history of hypertension, heart failure, cerebrovascular disease, chronic lung disease, diabetes mellitus), status at time of percutaneous coronary intervention (i.e., clinical presentation), cardiogenic shock within 24 hours, pre-procedure creatinine, pre-procedure hemoglobin, systolic blood pressure), procedural factors (culprit lesion, pre-stenosis percentage, arterial access site), and post-procedural factors (beta-blockers at discharge, prasugrel at discharge, ticagrelor at discharge, and length of stay). Patients with Medicare were more likely to be readmitted than patients with Blue Cross/Blue Shield, Geisinger Health Plan, or other insurance.
| All Patients (n = 6265) | Readmitted within 1 Year | Not Readmitted (n = 3498) | Readmitted vs Not Readmitted P-Value | |||
| n | % | n | % | n | % |
|
Age, mean (SD) | 64.3 (12.2) | 65.3 (12.8) | 63.5 (11.7) | < 0> | |||
Male | 4401 | 70.2% | 1830 | 66.1% | 2571 | 73.5% | < 0> |
Body mass index, mean (SD) | 30.7 (6.8) | 30.3 (7.2) | 30.9 (6.4) | 0.0013 | |||
Insurance Payors |
|
|
|
|
|
| < 0> |
Blue cross/Blue Shield | 744 | 11.9% | 259 | 9.4% | 485 | 13.9% |
|
Geisinger Health | 2345 | 37.4% | 982 | 35.5% | 1363 | 39.0% |
|
Medicaid | 37 | 0.6% | 17 | 0.6% | 20 | 0.6% |
|
Medicare | 2215 | 35.4% | 1108 | 40.0% | 1107 | 31.6% |
|
Others | 924 | 14.7% | 401 | 14.5% | 523 | 15.0% |
|
Hypertension | 4908 | 78.3% | 2273 | 82.1% | 2635 | 75.3% | < 0> |
Dyslipidemia | 4746 | 75.8% | 2137 | 77.2% | 2609 | 74.6% | 0.0152 |
Family History of Premature Coronary Artery Disease | 2219 | 35.4% | 930 | 33.6% | 1289 | 36.8% | 0.0078 |
Prior Myocardial Infarction | 1410 | 22.5% | 698 | 25.2% | 712 | 20.4% | < 0> |
Prior Heart Failure | 653 | 10.4% | 389 | 14.1% | 264 | 7.5% | < 0> |
Prior Valve Surgery/Procedure | 109 | 1.7% | 68 | 2.5% | 41 | 1.2% | 0.0001 |
Prior Percutaneous Coronary Intervention | 1444 | 23.0% | 684 | 24.7% | 760 | 21.7% | 0.0052 |
Prior Coronary Artery Bypass Surgery | 871 | 13.9% | 462 | 16.7% | 409 | 11.7% | < 0> |
Currently on Dialysis | 112 | 1.8% | 86 | 3.1% | 26 | 0.7% | < 0> |
Cerebrovascular Disease | 645 | 10.3% | 387 | 14.0% | 258 | 7.4% | < 0> |
Chronic Lung Disease | 701 | 11.2% | 387 | 14.0% | 314 | 9.0% | < 0> |
Diabetes Mellitus | 2123 | 33.9% | 1088 | 39.3% | 1035 | 29.6% | < 0> |
CAD Presentation |
|
|
|
|
|
| < 0> |
No Symptoms, No Angina | 289 | 4.6% | 152 | 5.5% | 137 | 3.9% |
|
Non-STEMI | 1455 | 23.2% | 664 | 24.0% | 791 | 22.6% |
|
STEMI or Equivalent | 1542 | 24.6% | 660 | 23.9% | 882 | 25.2% |
|
Stable Angina | 917 | 14.7% | 332 | 12.0% | 585 | 16.7% |
|
Symptom Unlikely to be Ischemic | 58 | 0.9% | 21 | 0.8% | 37 | 1.1% |
|
Unstable Angina | 1998 | 31.9% | 933 | 33.8% | 1065 | 30.5% |
|
Missing | 6 | 0.1% | 5 | 0.2% | 1 | 0.0% |
|
Heart Failure Within 2 Weeks | 539 | 8.6% | 333 | 12.1% | 206 | 5.9% | < 0> |
Cardiomyopathy or LV Systolic Dysfunction | 626 | 10.0% | 331 | 12.0% | 295 | 8.4% | < 0> |
Cardiogenic Shock Within 24 Hours | 121 | 1.9% | 75 | 2.7% | 46 | 1.3% | < 0> |
Contrast Volume, mean (SD) | 177.3 (77.8) | 173.3 (77.8) | 180.4 (77.7) | 0.0005 | |||
Intra-aortic Balloon Pump | 160 | 2.6% | 96 | 3.5% | 64 | 1.8% | < 0> |
Arterial Access Site |
|
|
|
|
|
| < 0> |
Femoral | 2938 | 46.9% | 1413 | 51.1% | 1525 | 43.6% |
|
Radial | 3307 | 52.8% | 1345 | 48.6% | 1962 | 56.1% |
|
Brachial/Others | 18 | 0.3% | 8 | 0.3% | 10 | 0.3% |
|
Missing | 2 | 0.0% | 1 | 0.0% | 1 | 0.0% |
|
PCI Status |
|
|
|
|
|
| < 0> |
Elective | 1762 | 28.4% | 682 | 25.0% | 1080 | 31.1% |
|
Emergency | 1609 | 25.9% | 691 | 25.3% | 918 | 26.4% |
|
Salvage | 58 | 0.9% | 28 | 1.0% | 30 | 0.9% |
|
Urgent | 2777 | 44.7% | 1332 | 48.7% | 1445 | 41.6% |
|
Missing | 59 | 0.9% | 34 | 1.2% | 25 | 0.7% |
|
Cardiogenic Shock at Start of PCI | 126 | 2.0% | 69 | 2.5% | 57 | 1.6% | 0.0138 |
Pre PCI Creatinine, median (IQR) (n missing = 297) | 0.9 (0.8, 1.1) | 1.0 (0.8, 1.2) | 0.9 (0.8, 1.1) | < 0> | |||
Pre PCI Hemoglobin, mean (STD) | 13.7 (1.9) | 13.3 (2.0) | 14.0 (1.7) | < 0> | |||
Discharge Medication |
|
|
|
|
|
|
|
Aspirin | 6071 | 96.9% | 2665 | 96.3% | 3406 | 97.4% | 0.0165 |
Clopidogrel | 5191 | 82.9% | 2228 | 80.5% | 2963 | 84.7% | < 0> |
Ticagrelor | 486 | 7.8% | 247 | 8.9% | 239 | 6.8% | 0.0021 |
Lesions Characteristic |
|
|
|
|
|
|
|
Thrombus | 1916 | 30.6% | 792 | 28.6% | 1124 | 32.1% | 0.0028 |
Previous Analysis |
|
|
|
|
|
|
|
Year of Intervention |
|
|
|
|
|
| < 0> |
2010 | 1156 | 18.5% | 450 | 16.3% | 706 | 20.2% |
|
2011 | 1029 | 16.4% | 425 | 15.4% | 604 | 17.3% |
|
2012 | 933 | 14.9% | 370 | 13.4% | 563 | 16.1% |
|
2013 | 1061 | 16.9% | 523 | 18.9% | 538 | 15.4% |
|
2014 | 1098 | 17.5% | 524 | 18.9% | 574 | 16.4% |
|
2015 | 988 | 15.8% | 475 | 17.2% | 513 | 14.7% |
|
Charlson Comorbidity Index on Procedure Date |
|
|
|
|
|
| < 0> |
0 | 368 | 5.9% | 144 | 5.2% | 224 | 6.4% |
|
1 to 2 | 2159 | 34.5% | 802 | 29.0% | 1357 | 38.8% |
|
≥ 3 | 3738 | 59.7% | 1821 | 65.8% | 1917 | 54.8% |
|
Duration of Index Hospitalization |
|
|
|
|
|
| < 0> |
0 to 3 Days | 4472 | 71.4% | 1780 | 64.3% | 2692 | 77.0% |
|
4 to 7 Days | 1387 | 22.1% | 720 | 26.0% | 667 | 19.1% |
|
> 7 Days | 406 | 6.5% | 267 | 9.6% | 139 | 4.0% |
|
Table 2: Summary of patient and encounter characteristics overall and by readmitted and not readmitted, excluding those not used in bootstrap variable selection an excluding those without significant differences between those readmitted and not readmitted.
STEMI = ST elevation myocardial infarction, PCI = Percutaneous Coronary Intervention, SD = standard deviation, IQR = Inter-quartile range, CK-MB = Creatine Kinase-Myocardial Band
Readmission within 365 Days (n = 6265) | OR | 95% CI Upper, Lower | P-Value | |
Age Quadratic- Age 55 (Q1) one year increase | 0.974 | 0.965 | 0.983 | < 0> |
Age Quadratic- Age 64 (Median)one year increase | 0.991 | 0.984 | 0.998 | |
Age Quadratic- Age 73 (Q3) one year increase | 1.008 | 0.999 | 1.016 | |
Body Mass Index (1 unit increase for BMI < 30> | 0.958 | 0.939 | 0.978 | 0.0001 |
Body Mass Index (1 unit increase for BMI ≥ 30) | 1.007 | 0.995 | 1.020 | |
Insurance: Geisinger vs Blue Cross/Blue Shield | 1.181 | 0.980 | 1.422 | 0.0014 |
Insurance: Medicaid vs Blue Cross/Blue Shield | 1.397 | 0.689 | 2.832 | |
Insurance: Medicare vs Blue Cross/Blue Shield | 1.447 | 1.191 | 1.758 | |
Insurance: Others vs Blue Cross/Blue Shield | 1.198 | 0.969 | 1.480 | |
Hypertension | 1.350 | 1.174 | 1.552 | < 0> |
Prior Heart Failure | 1.328 | 1.086 | 1.624 | 0.0057 |
Cerebrovascular Disease | 1.663 | 1.390 | 1.989 | < 0> |
Chronic Lung Disease | 1.258 | 1.060 | 1.493 | 0.0085 |
Diabetes Mellitus | 1.268 | 1.120 | 1.434 | 0.0002 |
Coronary Disease Presentation: No Symptoms/No Angina vs Unlikely Ischemic | 1.754 | 0.943 | 3.262 | 0.0023 |
Coronary Disease Presentation: Non-STEMI vs Unlikely Ischemic | 1.477 | 0.825 | 2.645 | |
Coronary Disease Presentation: STEMI vs Unlikely Ischemic | 1.428 | 0.746 | 2.732 | |
Coronary Disease Presentation: Stable Angina vs Unlikely Ischemic | 1.327 | 0.738 | 2.386 | |
Coronary Disease Presentation: Unstable Angina vs Unlikely Ischemic | 1.815 | 1.022 | 3.223 | |
Cardiogenic Shock within 24 Hours | 1.593 | 1.030 | 2.464 | 0.0363 |
Fluoroscopy Time (1 minute increase for time ≥ 19) | 1.004 | 0.997 | 1.011 | |
Procedure Diagnostic | 1.288 | 1.048 | 1.583 | 0.0161 |
Arterial Access: Radial vs Femoral | 0.815 | 0.725 | 0.916 | 0.0024 |
Arterial Access: Brachial/Others vs Femoral | 1.095 | 0.417 | 2.874 | |
PCI Scheduling Status: Emergency vs Elective | 1.464 | 1.050 | 2.042 | 0.0062 |
PCI Scheduling Status: Salvage vs Elective | 0.933 | 0.482 | 1.805 | |
PCI Scheduling Status: Urgent vs Elective | 1.299 | 1.099 | 1.535 | |
Creatinine Pre-Procedure (0.1 increase for < 0> | 0.896 | 0.828 | 0.969 | 0.0005 |
Creatinine Pre-Procedure (0.1 increase for ≥ 0.8) | 1.017 | 1.007 | 1.027 | |
Hemoglobin Pre-Procedure (1 unit increase for < 15> | 0.906 | 0.867 | 0.946 | < 0> |
Hemoglobin Pre-Procedure (1 unit increase for ≥ 15) | 0.976 | 0.874 | 1.090 | |
Beta Blockers at Discharge | 0.822 | 0.688 | 0.983 | 0.0316 |
Prasugrel at Discharge | 1.317 | 1.033 | 1.679 | 0.0263 |
Ticagrelor at Discharge | 1.519 | 1.052 | 2.193 | 0.0257 |
Culprit Lesion Identification vs Unknown | 0.760 | 0.641 | 0.901 | 0.0016 |
Pre-Stenosis Percent (1 unit increase) | 0.993 | 0.987 | 0.999 | 0.0152 |
Systolic Blood Pressure (1 unit increase < 120> | 0.989 | 0.981 | 0.997 | 0.0269 |
Systolic Blood Pressure (1 unit increase ≥ 120) | 1.003 | 0.999 | 1.007 | |
Procedure Year: 2011 vs 2010 | 1.135 | 0.946 | 1.361 | < 0> |
Procedure Year: 2012 vs 2010 | 1.130 | 0.934 | 1.367 | |
Procedure Year: 2013 vs 2010 | 1.796 | 1.489 | 2.166 | |
Procedure Year: 2014 vs 2010 | 1.653 | 1.367 | 1.999 | |
Procedure Year: 2015 vs 2010 | 1.773 | 1.447 | 2.172 | |
Charlson Comorbidity Index on Cath Date (3 vs 0) | 1.359 | 1.000 | 1.848 | |
Length of Stay: (4-7 Days vs 0 to 3 Days) | 1.258 | 1.094 | 1.446 | < 0> |
Length of Stay: (> 7 Days vs 0 to 3 Days) | 1.712 | 1.331 | 2.201 |
Table 3: Multivariable Binary Logistic Regression Results for Outcome of Readmitted within 365 Days and Not Readmitted
STEMI = ST elevation myocardial infarction, PCI = Percutaneous Coronary Intervention, SD = standard deviation, BMI = Body Mass Index
Acute coronary syndrome patients were more likely to be readmitted compared to patients with stable or unlikely ischemic presentations. Radial access patients were less likely to be readmitted compared to femoral access patients. Emergency and urgent procedure patients had higher odds of readmission compared to elective procedure patients. A non-linear association between systolic blood pressure and readmission was observed - as systolic pressure increased for patients with systolic pressure < 120>
Correlates of readmission Days 1-30 days versus Days 31 -334: Most characteristics associated with 1 to 30-day readmission by multivariable nominal logistic regression were also associated with admission from 31-334 days, but some differences were observed (Tables 4,5).
| All Patients | Readmission within 30 Days | Readmission 31-365 Days | Not Readmitted | 30 Day Readmission vs Not Readmitted | 31-365 Day Readmission vs Not Readmitted P-Value | ||||
| n | % | n | % | n | % | n | % | ||
Age, mean (SD) | 64.3 (12.2) | 65.2 (13.1) | 65.4 (12.6) | 63.5 (11.7) | 0.0002 | < 0> | ||||
Male | 4401 | 70.2% | 578 | 62.1% | 1252 | 68.2% | 2571 | 73.5% | < 0> | < 0> |
Body Mass Index, mean (SD) | 30.7 (6.8) | 30.0 (7.2) | 30.5 (7.1) | 30.9 (6.4) | 0.0001 | 0.0676 | ||||
Insurance Payors |
|
|
|
|
|
|
|
| < 0> | < 0> |
Blue cross/Blue Shield | 744 | 11.9% | 92 | 9.9% | 167 | 9.1% | 485 | 13.9% |
|
|
Geisinger Health | 2345 | 37.4% | 314 | 33.7% | 668 | 36.4% | 1363 | 39.0% |
|
|
Medicaid | 37 | 0.6% | 9 | 1.0% | 8 | 0.4% | 20 | 0.6% |
|
|
Medicare | 2215 | 35.4% | 361 | 38.8% | 747 | 40.7% | 1107 | 31.6% |
|
|
Others | 924 | 14.7% | 155 | 16.6% | 246 | 13.4% | 523 | 15.0% |
|
|
Hypertension | 4908 | 78.3% | 764 | 82.1% | 1509 | 82.2% | 2635 | 75.3% | < 0> | < 0> |
Dyslipidemia | 4746 | 75.8% | 697 | 74.9% | 1440 | 78.4% | 2609 | 74.6% | 0.8613 | 0.0018 |
Family History of Premature Coronary Artery Disease | 2219 | 35.4% | 307 | 33.0% | 623 | 33.9% | 1289 | 36.8% | 0.0288 | 0.0348 |
Prior Myocardial Infarction | 1410 | 22.5% | 199 | 21.4% | 499 | 27.2% | 712 | 20.4% | 0.4935 | < 0> |
Prior Heart Failure | 653 | 10.4% | 130 | 14.0% | 259 | 14.1% | 264 | 7.5% | < 0> | < 0> |
Prior Valve Surgery/Procedure | 109 | 1.7% | 24 | 2.6% | 44 | 2.4% | 41 | 1.2% | 0.0020 | 0.0009 |
Prior PCI | 1444 | 23.0% | 196 | 21.1% | 488 | 26.6% | 760 | 21.7% | 0.6568 | < 0> |
Prior Coronary Artery Bypass Surgery | 871 | 13.9% | 123 | 13.2% | 339 | 18.5% | 409 | 11.7% | 0.2047 | < 0> |
Currently on Dialysis | 112 | 1.8% | 30 | 3.2% | 56 | 3.1% | 26 | 0.7% | < 0> | < 0> |
Cerebrovascular Disease | 645 | 10.3% | 124 | 13.3% | 263 | 14.3% | 258 | 7.4% | < 0> | < 0> |
Chronic Lung Disease | 701 | 11.2% | 131 | 14.1% | 256 | 13.9% | 314 | 9.0% | < 0> | < 0> |
Diabetes Mellitus | 2123 | 33.9% | 354 | 38.0% | 734 | 40.0% | 1035 | 29.6% | < 0> | < 0> |
Coronary Artery Disease Presentation |
|
|
|
|
|
|
|
| < 0> | < 0> |
No Symptoms, No Angina | 289 | 4.6% | 44 | 4.7% | 108 | 5.9% | 137 | 3.9% |
|
|
Non-STEMI | 1455 | 23.2% | 233 | 25.0% | 431 | 23.5% | 791 | 22.6% |
|
|
STEMI or Equivalent | 1542 | 24.6% | 266 | 28.6% | 394 | 21.5% | 882 | 25.2% |
|
|
Stable Angina | 917 | 14.7% | 91 | 9.8% | 241 | 13.2% | 585 | 16.7% |
|
|
Symptom Unlikely to be Ischemic | 58 | 0.9% | 12 | 1.3% | 9 | 0.5% | 37 | 1.1% |
|
|
Unstable Angina | 1998 | 31.9% | 285 | 30.6% | 648 | 35.4% | 1065 | 30.5% |
|
|
Missing | 6 | 0.1% | 0 | 0.0% | 5 | 0.3% | 1 | 0.0% |
|
|
Heart Failure Within 2 Weeks | 539 | 8.6% | 118 | 12.7% | 215 | 11.8% | 206 | 5.9% | < 0> | < 0> |
Cardiomyopathy or LV Systolic Dysfunction | 626 | 10.0% | 120 | 12.9% | 211 | 11.6% | 295 | 8.4% | < 0> | 0.0002 |
Cardiogenic Shock Within 24 Hours | 121 | 1.9% | 38 | 4.1% | 37 | 2.0% | 46 | 1.3% | < 0> | 0.0492 |
Cardiac Arrest Within 24 Hours | 142 | 2.3% | 28 | 3.0% | 39 | 2.1% | 75 | 2.1% | 0.1234 | 0.9772 |
Contrast Volume, mean (SD) | 177.3 (77.8) | 171.6 (76.1) | 174.2 (78.7) | 180.4 (77.7) | 0.0028 | 0.0074 | ||||
IABP | 160 | 2.6% | 42 | 4.5% | 54 | 2.9% | 64 | 1.8% | < 0> | 0.0094 |
Arterial Access Site |
|
|
|
|
|
|
|
| 0.0005 | < 0> |
Femoral | 2938 | 46.9% | 471 | 50.6% | 942 | 51.3% | 1525 | 43.6% |
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|
Radial | 3307 | 52.8% | 456 | 49.0% | 889 | 48.4% | 1962 | 56.1% |
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Brachial/Others | 18 | 0.3% | 4 | 0.4% | 4 | 0.2% | 10 | 0.3% |
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Missing | 2 | 0.0% | 0 | 0.0% | 1 | 0.1% | 1 | 0.0% |
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PCI Status |
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|
|
|
|
|
| < 0> | 0.0001 |
Elective | 1762 | 28.4% | 174 | 18.9% | 508 | 28.0% | 1080 | 31.1% |
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Emergency | 1609 | 25.9% | 270 | 29.3% | 421 | 23.2% | 918 | 26.4% |
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Salvage | 58 | 0.9% | 16 | 1.7% | 12 | 0.7% | 30 | 0.9% |
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Urgent | 2777 | 44.7% | 460 | 50.0% | 872 | 48.1% | 1445 | 41.6% |
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Missing | 59 | 0.9% | 11 | 1.2% | 23 | 1.3% | 25 | 0.7% |
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Cardiogenic Shock at Start of PCI | 126 | 2.0% | 37 | 4.0% | 32 | 1.8% | 57 | 1.6% | < 0> | 0.7307 |
Pre Creatinine, median (IQR) | 0.9 (0.8, 1.1) | 0.9 (0.8, 1.2) | 1.0 (0.8, 1.2) | 0.9 (0.8, 1.1) | < 0> | < 0> | ||||
Pre Hemoglobin, mean (STD) | 13.7 (1.9) | 13.2 (2.0) | 13.4 (2.0) | 14.0 (1.7) | < 0> | < 0> | ||||
Discharge Medication |
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|
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|
|
|
|
Aspirin | 6071 | 96.9% | 901 | 96.8% | 1764 | 96.1% | 3406 | 97.4% | 0.3270 | 0.0099 |
Lipid Lowering Agents (Statins and Non-Statins) | 6028 | 96.2% | 893 | 95.9% | 1746 | 95.1% | 3389 | 96.9% | 0.1448 | 0.0012 |
Thienopyridines |
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|
|
|
|
|
|
|
|
|
Clopidogrel | 5191 | 82.9% | 735 | 78.9% | 1493 | 81.3% | 2963 | 84.7% | < 0> | 0.0015 |
Ticagrelor | 486 | 7.8% | 95 | 10.2% | 152 | 8.3% | 239 | 6.8% | 0.0006 | 0.0545 |
Lesions and Devices |
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|
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Pre-Stenosis Percent, median (IQR) | 95 (90, 100) | 95 (90, 100) | 95 (90, 100) | 95 (90, 100) | 0.8073 | 0.0326 | ||||
Thrombus | 1916 | 30.6% | 302 | 32.4% | 490 | 26.7% | 1124 | 32.1% | 0.8592 | < 0> |
Previous Analysis |
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Year of Intervention |
|
|
|
|
|
|
|
| < 0> | < 0> |
2010 | 1156 | 18.5% | 146 | 15.7% | 304 | 16.6% | 706 | 20.2% |
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|
2011 | 1029 | 16.4% | 139 | 14.9% | 286 | 15.6% | 604 | 17.3% |
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|
2012 | 933 | 14.9% | 115 | 12.4% | 255 | 13.9% | 563 | 16.1% |
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|
2013 | 1061 | 16.9% | 171 | 18.4% | 352 | 19.2% | 538 | 15.4% |
|
|
2014 | 1098 | 17.5% | 184 | 19.8% | 340 | 18.5% | 574 | 16.4% |
|
|
2015 | 988 | 15.8% | 176 | 18.9% | 299 | 16.3% | 513 | 14.7% |
|
|
Charlson Comorbidity Index on Procedure Date |
|
|
|
|
|
|
|
| < 0> | < 0> |
0 | 368 | 5.9% | 40 | 4.3% | 104 | 5.7% | 224 | 6.4% |
|
|
1 to 2 | 2159 | 34.5% | 285 | 30.6% | 517 | 28.2% | 1357 | 38.8% |
|
|
≥ 3 | 3738 | 59.7% | 606 | 65.1% | 1215 | 66.2% | 1917 | 54.8% |
|
|
Duration of Index Hospitalization |
|
|
|
|
|
|
|
| < 0> | < 0> |
0 to 3 Days | 4472 | 71.4% | 536 | 57.6% | 1244 | 67.8% | 2692 | 77.0% |
|
|
4 to 7 Days | 1387 | 22.1% | 277 | 29.8% | 443 | 24.1% | 667 | 19.1% |
|
|
> 7 Days | 406 | 6.5% | 118 | 12.7% | 149 | 8.1% | 139 | 4.0% |
|
|
Table 4: Summary of Patient and Encounter Characteristics Overall and by Readmitted Days 1-30, Readmitted Days 31 - 365, and Not Readmitted, Excluding those not use in bootstrap variable selection
STEMI = ST elevation myocardial infarction, PCI = Percutaneous Coronary Intervention, SD = standard deviation, IQR = Inter-quartile range, CK-MB = Creatine Kinase-Myocardial Band, CCS= Canadian Cardiovascular Society Class
Readmission within 30 Days, Readmssion Between 31 and 365 Days, and Not Readmitted (n = 6265) | Readmission within 30 Days vs Not Readmitted | Readmission 31-365 Days vs Not Readmitted | ||||||
OR | 95% CI | P-Value | OR | 95% CI | P-Value | |||
Age Quadratic- Age 55 (Q1) one year increase | 0.966 | 0.953 | 0.978 | < 0> | 0.981 | 0.971 | 0.992 | < 0> |
Age Quadratic- Age 64 (Median) one year increase | 0.986 | 0.976 | 0.995 | 0.995 | 0.987 | 1.003 | ||
Age Quadratic- Age 73 (Q2) one year increase | 1.006 | 0.994 | 1.018 | 1.010 | 1.000 | 1.019 | ||
BMI (1 unit increase for BMI < 30> | 0.949 | 0.924 | 0.976 | 0.0001 | 0.964 | 0.943 | 0.986 | 0.0056 |
BMI (1 unit increase for BMI ≥ 30) | 0.995 | 0.978 | 1.014 | 1.012 | 0.998 | 1.025 | ||
Insurance: Geisinger vs Blue Cross/Blue Shield | 1.105 | 0.840 | 1.453 | 0.0838 | 1.213 | 0.980 | 1.502 | 0.0026 |
Insurance: Medicaid vs Blue Cross/Blue Shield | 2.014 | 0.836 | 4.850 | 1.034 | 0.432 | 2.479 | ||
Insurance: Medicare vs Blue Cross/Blue Shield | 1.333 | 1.003 | 1.771 | 1.482 | 1.187 | 1.851 | ||
Insurance: Others vs Blue Cross/Blue Shield | 1.301 | 0.960 | 1.762 | 1.139 | 0.892 | 1.454 | ||
Recent Smoker | 0.949 | 0.786 | 1.146 | 0.5874 | 1.158 | 1.001 | 1.340 | 0.0485 |
Hypertension | 1.550 | 1.259 | 1.907 | < 0> | 1.249 | 1.065 | 1.464 | 0.0062 |
Prior Myocardial Infarction | 0.943 | 0.773 | 1.150 | 0.5628 | 1.174 | 1.012 | 1.362 | 0.0344 |
Previous Coronary Bypass Surgery | 0.951 | 0.735 | 1.230 | 0.6993 | 1.222 | 1.012 | 1.474 | 0.0369 |
Cerebrovascular Disease | 1.576 | 1.232 | 2.016 | 0.0003 | 1.665 | 1.370 | 2.024 | < 0> |
Diabetes Mellitus | 1.237 | 1.036 | 1.478 | 0.0188 | 1.271 | 1.107 | 1.459 | 0.0007 |
Coronary disease Presentation: No Symptoms/No Angina vs Unlikely Ischemic | 0.950 | 0.416 | 2.168 | 0.0725 | 2.916 | 1.277 | 6.659 | 0.0012 |
Coronary disease Presentation: Non-STEMI vs Unlikely Ischemic | 0.792 | 0.374 | 1.676 | 2.189 | 0.998 | 4.800 | ||
Coronary disease Presentation: STEMI vs Unlikely Ischemic | 0.936 | 0.401 | 2.182 | 1.934 | 0.827 | 4.520 | ||
Coronary disease Presentation: Stable Angina vs Unlikely Ischemic | 0.632 | 0.296 | 1.349 | 1.998 | 0.912 | 4.378 | ||
Coronary disease Presentation: Unstable Angina vs Unlikely Ischemic | 0.988 | 0.472 | 2.068 | 2.767 | 1.271 | 6.024 | ||
Cardiogenic Shock within 24 Hours | 1.818 | 1.076 | 3.070 | 0.0254 | 1.414 | 0.855 | 2.338 | 0.1769 |
Fluoroscopy Time (1 minute increase for time < 19> | 0.977 | 0.961 | 0.994 | 0.0258 | 0.987 | 0.974 | 1.000 | 0.1376 |
Fluoroscopy Time (1 minute increase for time ≥ 19) | 1.007 | 0.997 | 1.017 | 1.002 | 0.994 | 1.009 | ||
Procedure Diagnostic | 1.461 | 1.094 | 1.950 | 0.0101 | 1.298 | 1.042 | 1.616 | 0.0201 |
Arterial Access: Radial vs Femoral | 0.886 | 0.745 | 1.054 | 0.1919 | 0.812 | 0.710 | 0.930 | 0.0104 |
Arterial Access: Brachial/Others vs Femoral | 1.947 | 0.580 | 6.540 | 0.770 | 0.233 | 2.543 | ||
PCI Scheduling Status: Emergency vs Elective | 1.690 | 1.049 | 2.723 | 0.0039 | 1.437 | 0.986 | 2.093 | 0.0352 |
PCI Scheduling Status: Salvage vs Elective | 1.361 | 0.597 | 3.103 | 0.681 | 0.303 | 1.534 | ||
PCI Scheduling Status: Urgent vs Elective | 1.609 | 1.241 | 2.085 | 1.213 | 1.004 | 1.465 | ||
Creatinine Pre-Procedure (0.1 increase for < 0> | 0.965 | 0.858 | 1.084 | 0.3804 | 0.890 | 0.812 | 0.976 | 0.0156 |
Creatinine Pre-Procedure (0.1 increase for ≥ 0.8) | 1.011 | 0.995 | 1.027 | 1.013 | 0.999 | 1.027 | ||
Hemoglobin Pre-Procedure (1 unit increase for < 15> | 0.898 | 0.844 | 0.954 | 0.0015 | 0.926 | 0.880 | 0.973 | 0.0036 |
Hemoglobin Pre-Procedure (1 unit increase for ≥ 15) | 1.001 | 0.850 | 1.179 | 0.970 | 0.854 | 1.100 | ||
Prasugrel at Discharge | 1.358 | 0.959 | 1.924 | 0.0849 | 1.331 | 1.014 | 1.745 | 0.0392 |
Ticagrelor at Discharge | 1.636 | 0.989 | 2.704 | 0.0550 | 1.519 | 1.001 | 2.306 | 0.0496 |
Culprit Lesion Identification vs Unknown | 0.743 | 0.580 | 0.952 | 0.0188 | 0.765 | 0.634 | 0.922 | 0.0050 |
Pre-Stenosis Percent (1 unit increase) | 0.992 | 0.983 | 1.000 | 0.0604 | 0.992 | 0.986 | 0.999 | 0.0219 |
Diastolic Blood Pressure (1 unit increase ≥ 70) | 1.005 | 0.992 | 1.018 | 1.006 | 0.996 | 1.016 | ||
Procedure Year: 2011 vs 2010 | 1.140 | 0.870 | 1.493 | < 0> | 1.155 | 0.941 | 1.417 | < 0> |
Procedure Year: 2012 vs 2010 | 1.085 | 0.816 | 1.444 | 1.160 | 0.936 | 1.437 | ||
Procedure Year: 2013 vs 2010 | 1.812 | 1.379 | 2.382 | 1.761 | 1.426 | 2.175 | ||
Procedure Year: 2014 vs 2010 | 1.703 | 1.282 | 2.263 | 1.507 | 1.207 | 1.882 | ||
Procedure Year: 2015 vs 2010 | 1.861 | 1.361 | 2.545 | 1.515 | 1.182 | 1.941 | ||
Charlson Comorbidity Index on Cath Date (1 to 2 vs 0) | 1.631 | 1.086 | 2.448 | 0.0180 | 0.945 | 0.703 | 1.270 | 0.2158 |
Charlson Comorbidity Index on Cath Date (3 vs 0) | 1.945 | 1.226 | 3.085 | 1.102 | 0.782 | 1.552 | ||
Length of Stay: (4-7 Days vs 0 to 3 Days) | 1.467 | 1.210 | 1.779 | < 0> | 1.157 | 0.988 | 1.355 | 0.0186 |
Length of Stay: (> 7 Days vs 0 to 3 Days) | 2.180 | 1.590 | 2.989 | 1.449 | 1.091 | 1.923 |
Table 5: Multivariable Multinomial Logistic Regression Results for Outcome of Readmitted within 30 Days, Readmitted Between 31 and 365 Days, and Not Readmitted
STEMI = ST elevation myocardial infarction, PCI = Percutaneous Coronary Intervention, SD = standard deviation, BMI = Body Mass Index
Factors correlating with later readmission, but NOT early readmission included smoking, prior MI, prior coronary artery bypass graft surgery, radial access, and creatinine. Factors associated with early readmission, but not later readmission included male gender, insurance status, pre-procedural angina classification, acute shock, radial access, beta blocker therapy at discharge, systolic blood pressure, and Charlson Co-morbidity Index.
The most important finding of this study is that the two-fifths of patients undergoing PCI were readmitted within one year of the procedure. Of those readmitted, one-third were readmitted within the first 30 days and two-thirds were readmitted over the next 11 months. Most studies of readmission after PCI focus only on 30-day re-admissions. Our study shows that a 30-day assessment is limited and under-estimates the burden of morbidity in post-PCI patients. Care of post-PCI patients beyond 30 days should be of interest to the interventionalist.
Only two factors over which clinicians have control were associated with likelihood of readmission. First, radial access (versus femoral access) had an odds ratio of .81 (p = 0.002) of re-admission. Multiple studies have demonstrated that radial access compared to femoral access decreases vascular complications and bleeding which might explain this correlation [6]. However, use of radial access correlated with reduced rates of late but not early re-admission which is inconsistent with the hypothesis that reduced rates of procedure-related vascular access complications or bleeding are responsible for the lower re-admission rates. The association with reduced late re-admissions may be due to unknown confounders related to co-morbidities, since femoral access was often reserved for older and sicker patients.
Second, beta-blockers at discharge were associated with an odds ratio of 0.82 (p = 0.03) of any readmission. The correlation was limited to readmissions within the first 30 days (odds ratio 0.74, p = 0.02) but not after 30 days (odds ratio 0.85, p = .11). This observation has been previously reported [7], but again we cannot exclude unknown confounders since the benefit of beta-blockers is unclear in patients without MI.
Several additional findings are of interest. Urgent and emergent PCI (linked to acute coronary syndromes) status was associated with a 30-46% excess rate of re-admission compared to elective (stable) PCI status. Patients discharged on ticagrelor or prasugrel had 31-52% excess re-admission rates compared to patients discharged on clopidogrel, perhaps because these drugs were used preferentially for acute coronary syndrome patients and because they increase bleeding risk compared to clopidogrel. Finally, length of stay of 4-7 days and > 7 days correlated with 26% and 71% increased risks of readmission, respectively, compared to shorter lengths of stay, presumably because length of stay is a marker for severity of the initial hospitalization and overall clinical status.
We are aware of only 1 other study that evaluated re-admissions up to 1 year after PCI [5]. That study was conducted in Denmark, where the National Health Service guarantees free hospital access. In the Danish cohort 50% of patients were re-admitted within 1 year compared to 44% in our study. Similar to our findings, the Denmark investigators concluded that readmission is common in the year following PCI, that many of the re-admissions are due to ischemic heart disease, that co-morbidities correlate most closely with readmission, and that we could identify few modifiable correlates of readmission. Both studies point to the importance of secondary risk factor modification and careful follow-up after PCI. Differences may be due in part to our inability to identify re-admissions to hospitals outside of our 13-hospital system, although we excluded patients lost-to follow-up from our initial cohort. Half of the Denmark patients were readmitted due to angina or myocardial infarction whereas two-thirds of our patients were readmitted with ischemia-related diagnoses. Both studies identified age, Charlson Comorbidity Index </=3, and diabetes as correlates of readmission. The Denmark study identified female gender as a correlate of readmission although our study did not, perhaps because of closer association with other demographic variables that were not available to the Denmark investigators. However, our study showed a 25% increased risk of readmission for women in the first 30 days that equalized over the next 11 months.
Readmission rates after PCI within 30 days have been extensively studied, perhaps because 30 days is the time window considered by the Center for Medicare and Medicaid Services Hospital Re-admission Reduction Program (HRRP). However, this focus may result in lack of focus on care of post-PCI patients over the next 11 months. Attendance at cardiac rehabilitation sessions, adherence to medications, and control of risk factors have all been shown to decrease morbidity and/or mortality after PCI [8-9]. Close follow-up by cardiovascular specialists is important to ensure these goals are met.
Our study has several limitations. We were unable to identify re-admissions to a non-Geisinger hospital, although Geisinger operates 13 hospitals in central and northeastern Pennsylvania where the population is very stable and where most patients treated at Geisinger return to Geisinger. The population included in this study was 98