The objective of our study was to assess patients with end-stage liver disease undergoing percutaneous coronary intervention (PCI) and determine the rates and trend of complications and in-hospital outcomes. Data were obtained from the Nationwide Inpatient Sample 2005 to 2012. We identified all PCIs performed in patients with diagnosis of cirrhosis during the study period by the International Classification of Diseases, Ninth Revision, Clinical Modification codes. Preventable procedural complications were identified by Patient Safety Indicators. Propensity scoring method was used to establish matched cohorts to control for imbalances and account for differences that may have influenced treatment outcomes. A total of 1,051,242 PCIs were performed during the study period, of these, 122,342 were done on subjects with a formal diagnosis of cirrhosis. Bare-metal stents (BMS) were more likely to be used in patients who presented with ST-elevation myocardial infarction (19.73 vs 13.58, p <0.001), in cardiogenic shock (5.58, vs 2.81, p <0.001), or required intraaortic balloon pump (4.73 vs 2.38, p <0.001). The overall rate of complications was 7.1%, whereas the overall mortality rate over these years was 3.63%. On a propensity-matched analysis the mortality rate was 2 times higher for BMS (5.18 vs 2.35, p <0.001) compared with drug-eluting stents. PCI remains a safe and plausible option for patients with cirrhosis albeit riskier than for the general population. The use of BMS is associated with increased mortality and bleeding complications compared with drug-eluting stents which likely is representative of preferential use of BMS in patients with more advanced end-stage liver disease who are also likely to experience higher postprocedural complications.
Cardiovascular disease remains one of the major causes of morbidity and mortality in end-stage liver disease (ESLD). Despite earlier reports of ESLD conferring a protective effect against coronary artery disease, more recent evidence has proved otherwise with a prevalence of up to 27% in patients with cirrhosis, and it continues to increase with age. In addition, liver disease is associated with thrombocytopenia and coagulopathy predisposing patients to bleeding complications, especially in those with esophageal varices. Studies have shown that most patients with ESLD have lower hemoglobin, higher INRs, and creatinine values than matched cohorts in average. Thus, patients with cirrhosis experience a higher frequency of peri-procedural bleeding, pseudoaneurysm formation, and the need for blood products. All these factors, increase in-hospital length of stay, cost, and patient mortality. To date, there is paucity of data on the postprocedural rate of complications in patients with cirrhosis undergoing percutaneous coronary interventions (PCIs), and more so comparing the outcomes with the use of these 2 main stent techniques in this unique population. The objective of our study was to assess the cohort of patients with ESLD undergoing PCI and determine the rates and trend of complications and in-hospital outcomes from the largest publicly available inpatient database in the United States from 2005 to 2012.
Methods
Data were obtained from the Nationwide Inpatient Sample (NIS) 2005 to 2012. NIS is a part of a family of databases developed for the Healthcare Cost and Utilization Project and is sponsored by the Agency for Healthcare Research and Quality. Data from the NIS have previously been used to identify, track, and analyze national trends in health care usage, patterns of major procedures, access, disparity of care, trends in hospitalizations, charges, quality, and outcomes. We identified all PCIs performed during the study period by International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes 36.06 for bare-metal stents (BMS) and 36.07 for drug-eluting stents (DES). Subjects with ESLD were identified using the ICD-9-CM codes 571.2, 571.5, 571.6 in any diagnostic field. Only patients aged >18 years were included, and observations with missing information were excluded. Both patient- and hospital-level variables were included in the baseline characteristics of the study population for assessment of potential confounders. Patient-level characteristics such as age, gender, race, co-morbid conditions using Deyo modification of Charlson Co-morbidity Index (CCI), median household income according to ZIP code, primary payer, admission type (urgent/emergent vs elective), day of the admission (weekdays vs weekend), and hospital-level characteristics such as hospital location (urban/rural), hospital bed size (small, medium, and large), region (Northeast, Midwest or North Central, South, and West), and teaching status were studied. We defined severity of co-morbid conditions using Deyo modification of CCI. This index contains 17 co-morbid conditions with differential weights. A higher score corresponds to greater burden of co-morbid diseases. Facilities were considered to be teaching hospitals if they had an American Medical Association approved residency program were a member of the Council of Teaching Hospitals or had a full-time equivalent intern and resident to patient ratio of 0.25 or higher.
The primary outcome was in-hospital all-cause mortality, and the secondary outcome was individual periprocedural complications. Preventable procedural complications were identified by Patient Safety Indicators (PSIs), which have been established by the Agency for Healthcare Research and Quality to monitor preventable adverse events during hospitalization. These indicators are based on ICD-9-CM codes and Medicare Severity Diagnosis-Related Groups, and each PSI has specific inclusion and exclusion criteria. PSI individual technical specifications were used to identify and define preventable procedural complications viz. postprocedure respiratory failure, postprocedure physiologic and metabolic derangement with acute renal failure requiring dialysis, postprocedure pulmonary embolism or deep vein thrombosis, and accidental puncture or laceration.
Other procedure-related complications including hemorrhage requiring blood transfusion, iatrogenic cardiac complications, pericardial complications, requiring open heart surgery, procedural stroke or transient ischemic attack, and vascular complications were identified using ICD-9-CM codes in any secondary diagnosis field. To prevent classification of a preexisting condition (e.g., stroke) as a complication, cases with the ICD-9-CM code for a complication listed as the principal diagnosis (DX1) were excluded. Vascular complications were defined as PSI code for accidental puncture or ICD-9-CM codes for injury to blood vessels, creation of arteriovenous fistula, injury to the retroperitoneum, vascular complications requiring surgery, and other vascular complications not elsewhere classified. “Any complication” was defined as occurrence of one or more procedural complications (listed in Supplementary Table 1 , which can be accessed online). This method has been used in previous studies.
Stata IC 11.0 (StataCorp, College Station, Texas) and SAS 9.3 (SAS Institute Inc, Cary, North Carolina) were used for analyses, which accounted for the complex survey design and clustering. For categorical variables such as in-hospital mortality and complications, the chi-square test of trend for proportions was used using the Cochrane–Armitage test through the “ptrend” command in Stata. For continuous variables, nonparametric test for trend by Cuzick (which is similar to Wilcoxon rank-sum test) using the “nptrend” command in Stata was used.
Differences in outcomes between drug-eluting and BMS were tested using the chi-square test. p Value of <0.05 was considered significant. We used propensity scoring method to establish matched cohorts to control for imbalances of patients’ and hospitals’ characteristics between the 2 different treatment groups (BMS vs DES), which may have influenced treatment outcome ( Table 4 ). A propensity score was assigned to each hospitalization based on multivariate logistic regression model that examined the impact of 12 variables (patient demographics, co-morbidities, and hospital characteristics) on the likelihood of treatment assignment. Patients with similar propensity score in the 2 treatment groups were matched using a 1 to 1 scheme without replacement using greedy algorithm.
Results
A total number of 1,051,242 PCIs were performed from 2005 to 2012. Of these procedures, 12,342 were done on subjects with a formal diagnosis of cirrhosis. Table 1 lists the baseline characteristics of the studied population. The distribution of procedures remained homogeneous during these years, with no significant overall trend of variation. The mean age of the study population was 63 ± 10.2 (mean ± SD) years. Majority of the patients were men (66%) and of non-Hispanic white ethnicity (63%). 63.7% of patients had a CCI score of 3 or more. Hypertension, diabetes, chronic pulmonary disease, and congestive heart failure were the most common co-morbidities. However, noteworthy, a history of coagulopathy (26%) and anemia (20.5%) was also predominant in this population. Acute myocardial infarction was identified in 44.2% of the patients (14.6% and 29.6% non–ST-elevation myocardial infarction [STEMI]), cardiogenic shock in 4%, and need for percutaneous hemodynamic support device placement in 4% of the patients. Most of these PCIs were performed at urban, large, teaching institutions, and in the South US. Furthermore, 3 quarters were on an emergent, or urgent, basis on weekdays, and most patients were discharged home at the end of hospitalization.
| Variables | Overall n=12342 |
|---|---|
| Age in years | |
| 18-49 | 8.39% |
| 50-59 | 31.79% |
| 60-69 | 33.11% |
| 70-79 | 20.41% |
| >=80 | 6.31% |
| Male | 66.21% |
| Female | 33.79% |
| White | 62.82% |
| Non-white | 20.05% |
| Missing | 17.13% |
| STEMI | 14.58% |
| Cardiogenic shock | 3.99% |
| IABP | 3.31% |
| PVAD | 0.4% |
| Comorbidities | |
| Charlson comorbidity index ∗ | |
| 1 | 11.26% |
| 2 | 25.04% |
| >=3 | 63.7% |
| Obesity | 11.26% |
| Hypertension | 62.82% |
| Diabetes Mellitus | 47.84% |
| Congestive Heart Failure | 27.52% |
| Chronic Pulmonary Disease | 24.52% |
| Pulmonary Circulatory Disorder | 0.92% |
| Peripheral Vascular Disease | 12.86% |
| Renal Failure | 18.85% |
| Neurological Disorder | 4.79% |
| Anemia | 20.49% |
| Coagulopathy | 25.96% |
| Hematological/ Oncological malignancy | 3.91% |
| Hepatorenal Syndrome | 0.84% |
| Median house hold income † (Quartile) | |
| 1st | 32.23 |
| 2nd | 25.29 |
| 3rd | 23.7 |
| 4th | 18.79 |
| Primary Insurance | |
| Medicare | 53.52 |
| Medicaid | 12.67% |
| Private Including Health Maintenance Organization | 25.5% |
| Uninsured/Self-Pay | 8.31% |
| Hospital Bed Size | |
| Small | 5.99% |
| Medium | 18.09% |
| Large | 75.91% |
| Hospital location | |
| Rural | 4.78% |
| Urban | 95.22% |
| Hospital Teaching Status | |
| Non-Teaching | 42.14% |
| Teaching | 57.86% |
| Hospital Region | |
| Northeast | 18% |
| Midwest | 21.28% |
| South | 41.62% |
| West | 19.1% |
| Type of Admission | |
| Emergent or Urgent | 76.77% |
| Elective | 23.23% |
| Type of Stents | |
| Bare Metal Stents | 44.76% |
| Drug Eluting Stents | 55.24% |
| Admission Day | |
| Weekdays | 84.07% |
| Weekend | 15.93% |
| Disposition Status | |
| Home | 77.32% |
| Acute care hospital | 1.6% |
| Nursing home | 8.43% |
| Home health care | 7.99% |
| Against medical advice | 0.96% |
| Died | 3.63% |
| Discharge alive, destination unknown | 0.08% |
∗ Charlson/Deyo Co-morbidity Index was calculated as per Deyo classification 1. Comorbidities were identified by ICD-9-CM code mentioned in any of the diagnostic fields.
† This represents a quartile classification of the estimated median household income of residents in the patient’s zip code. These values are derived from zip code-demographic data obtained from Claritas. The quartiles are identified by values of 1 to 4, indicating the poorest to wealthiest populations. Because these estimates are updated annually, the value ranges vary by year. STEMI = ST-elevation myocardial infarction; IABP = intraaortic balloon counterpulsation; PVAD = percutaneous ventricular assist devise. Anemia definition is contingent with that of the Healthcare Cost and Utilization Project, sponsored by the Agency for Healthcare Research and Quality ( http://www.hcup-us.ahrq.gov/db/vars/zipinc_qrtl/nisnote.jsp ).
There were significant differences in the baseline characteristics of the BMS versus DES groups ( Supplementary Table 2 , which can be accessed online). BMS were more likely to be used in patients who presented with STEMI, in cardiogenic shock, or required intraaortic balloon pump. Furthermore, BMS was more used for patients with a history of anemia, coagulopathy, or hematologic or oncological malignancy.
The overall rate of complications was 7.1%, whereas the overall mortality rate over these years was 3.63% ( Table 2 ). The latter initially increased and then remained constant over the past 3 years ( Table 2 ). Hemorrhagic events and need for transfusions were the most common complications ranging from 7% to 14%, respectively. Both of these were reported more commonly in the BMS group. Postprocedural sepsis was reported almost twice more frequently in the BMS group (4.34 vs 2.76, p <0.001). The comparison of outcomes between BMS and DES is reported in Table 3 .
| Complications | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | Overall |
|---|---|---|---|---|---|---|---|---|---|
| PCI in Cirrhosis | 1404 | 1477 | 1367 | 1508 | 1738 | 1384 | 1825 | 1640 | 12342 |
| Mortality | 2.1 | 3.3 | 4 | 4.56 | 4.31 | 3.3 | 3.91 | 3.35 | 3.63 |
| Vascular injury requiring surgery | 1.4 | 0.99 | 1.09 | 1.3 | 2.87 | 0.73 | 1.56 | 1.52 | 1.48 |
| Hemorrhage or acute blood loss anemia | 6.29 | 4.62 | 5.82 | 6.19 | 5.75 | 7.33 | 8.59 | 7.62 | 6.59 |
| Transfusion | 9.09 | 8.25 | 11.64 | 12.05 | 10.63 | 14.29 | 12.5 | 12.2 | 11.34 |
| Hemorrhage or acute blood loss anemia requiring transfusion | 1.75 | 1.65 | 2.18 | 2.61 | 2.01 | 2.93 | 2.86 | 3.35 | 2.44 |
| Cardiovascular complications | 2.1 | 2.31 | 2.18 | 1.95 | 1.15 | 2.56 | 1.3 | 2.13 | 1.92 |
| Requiring open heart surgery | 0.35 | 0 | 0 | 0 | 0.29 | 0.37 | 0 | 0 | 0.12 |
| Post operative respiratory failure | 2.8 | 4.95 | 4.36 | 3.26 | 2.87 | 3.3 | 6.77 | 3.05 | 3.99 |
| Post procedural stroke | 0.35 | 0 | 0 | 0 | 0 | 0.37 | 0 | 0 | 0.08 |
| Renal failure requiring dialysis | 0.35 | 0.66 | 0.73 | 0.33 | 1.15 | 1.1 | 1.04 | 1.22 | 0.84 |
| Pulmonary embolism or DVT | 0.7 | 1.32 | 1.09 | 1.95 | 0.29 | 1.47 | 0.26 | 0.3 | 0.88 |
| Sepsis | 1.4 | 3.3 | 6.55 | 3.58 | 3.16 | 2.56 | 3.91 | 3.05 | 3.43 |
| Complications | DES | BMS | P value |
|---|---|---|---|
| Overall | 6903% | 5439% | 12342 |
| Mortality | 2.35% | 5.18% | <0.001 |
| Vascular injury requiring surgery | 1.18% | 1.63% | 0.33 |
| Hemorrhage or acute blood loss anemia | 6.18% | 7.18% | 0.32 |
| Transfusion | 9.05% | 14.44% | <0.001 |
| Hemorrhage or acute blood loss anemia requiring transfusion | 1.69% | 3.36% | 0.008 |
| Cardiovascular complications | 1.99% | 1.82% | 0.76 |
| Requiring open heart surgery | 0.07% | 0.18% | 0.45 |
| Post operative respiratory failure | 3.97% | 4% | 0.98 |
| Post procedural stroke | 0.15% | 0 | 0.2 |
| Renal failure requiring dialysis | 0.81% | 0.82% | 0.98 |
| Pulmonary embolism or DVT | 0.66% | 1.18% | 0.89 |
| Sepsis | 2.72% | 4.27% | 0.04 |
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