Decreasing In-hospital Mortality of Patients Undergoing Percutaneous Coronary Intervention with Persistent (FULL TITLE BELOW)

ABSTRACT: Background. Advances in interventional techniques have been dramatic in the last 10 years. The goal of this study was to evaluate the age-adjusted in-hospital mortality rate in patients undergoing percutaneous coronary intervention (PCI) using a large database. Methods. The Nationwide Inpatient Sample (NIS) database was utilized to calculate the age-adjusted mortality rate for PCI from 1988 to 2004 in patients over the age of 40 retrospectively. Specific ICD-9-CM codes for PCI were used for this study. Demographic data were also analyzed and adjusted for age. Results. The mean age for these patients was 71.56 ± 10.59 years (53.55% male). From 1988 to 1995, the age-adjusted mortality rate was stable. However, after 1995 the age-adjusted mortality rate showed persistent decline to the lowest level in 2004. (In 1988, age-adjusted mortality rate was 75.43 per 100,000 [95% CI = -7.88–158.76], in 1995, 66.83 per 100,000 [95% CI = 24.62–109.050] and in 2004, 38.38 per 100,000 [95% CI 19.53–57.22]; p

J INVASIVE CARDIOL 2010;22:58–60

Key words: angioplasty; stent; epidemiology; cardiovascular disease; coronary artery disease; incident; prevalence
Percutaneous coronary intervention (PCI) is the most common interventional procedure for coronary artery revascularization. The number of PCI procedures has increased in recent years due to increased awareness and improved outcomes compared to fibrinolytic therapy for coronary artery disease (CAD).^1,2 Meta-analyses of randomized clinical trials have reported that primary PCI is more cost-effective compared to fibrinolysis and reduces the incidence of death, reinfarction, and stroke.^3–5 Furthermore, in stable patients and in patients with multivessel disease, PCI has become the preferred procedure in the United States,⁶ with declining mortality in patients undergoing multivessel PCI.⁷ Despite increasing utilization of PCI in the United States,⁸ the mortality trends from PCI based on race and gender have not been studied in recent years. We sought to identify the temporal trends of in-hospital PCI-related mortality in a large patient cohort from 1998 to 2004 in the United States based on gender and ethnicity.

Methods

The Nationwide Inpatient Sample (NIS)9 is a set of longitudinal hospital inpatient databases included in the Healthcare Cost and Utilization Project (HCUP). These databases are created by Agency for Healthcare Research and Quality (AHRQ) through a Federal-State-Industry partnership. HCUP data informs decision making at the national, state and community levels. Researchers and policymakers use the NIS to identify, track and analyze national trends in health-care utilization, access, charges, quality and outcomes. The NIS is the largest all-payer inpatient care database and contains data from approximately 8 million hospital stays each year in the U.S. NIS data are available from 1988 to 2006, allowing analysis of trends over time. The NIS is a national hospital database containing charge information on all patients regardless of payer, including persons covered by Medicare, Medicaid, private insurance and the uninsured. It also contains primary and secondary diagnoses, primary and secondary procedures, demographics, admission and discharge status with safeguards to protect the privacy of individual patients, physicians and hospitals. The NIS database was used to calculate the age-adjusted mortality rate for PCI from 1988 to 2004 in patients over the age of 40 years retrospectively based on gender and race. Specific ICD-9-CM codes for PCI were used to compile the data as follows: 36.01, 36.02, 36.05, 36.6 and 36.07 (Table 1). Patient demographic data were also analyzed and age-adjusted. The average age-adjusted mortality rates for PCI and the 95% confidence intervals (95% confidence interval [CI]) for each year were calculated by multiplying the age-specific mortality rates of PCI by age-specific weights in patients over the age of 40. The weights were the proportion of the year 2000 standard U.S. population within each age group used in the age-adjustment of the data. The weighted rates were for each year from 1988 to 2004 then summed among different age groups for the age-adjusted rate calculation. We used Statistical Package for the Social Sciences (SPSS) software for data analysis (SPSS, Inc., Chicago, Illinois).¹³ Quantitative variables were expressed as means ± standard deviation (SD). Trend statistics were performed using ANOVA for age-adjusted and total death analysis. A p-value less than 0.05 was deemed to be statistically significant.

Results

The mean age for these patients was 71.56 ± 10.59 years (53.55% male). From 1988 to 1995, the age-adjusted mortality rate was stable. However, after 1995, the age-adjusted mortality rate showed a persistent decline to the lowest level in 2004. In 1988, the age-adjusted mortality rate was 75.43 per 100,000 (95% CI= -7.88–158.76), in 1995, 66.83 per 100,000 (95% CI = 24.62–109.050) and in 2004, 38.38 per 100,000 (95% CI = 19.53–57.22); p Discussion After myocardial infarction (MI) an early invasive management such as PCI results in an improvement in long-term survival and reduction in late MI.¹⁰ Although fibrinolysis is an effective treatment for MI,¹¹ meta-analysis of the clinical trials have demonstrated that regardless of delay in treatment, primary PCI was associated with a reduction in 30-day mortality.⁴ Improved survival among PCI patients has been documented recently in England. It was demonstrated that among the PCI patients experiencing a 2-year event-free survival of 83% in the latter period (2001–2004), compared to just 73% in the earlier period (1995–1998).¹² Similarly, a retrospective cohort study on patients receiving PCI, 30-day mortality was significantly reduced in the recent period (1996 and 2004) compared with that in the early period, consistent with our results.¹³ Recently published data from the National Cardiovascular Data Registry confirmed our findings, also reporting a lower in-hospital mortality rate from PCI in recent years.¹⁴ Our study demonstrates that the age-adjusted inpatient’s mortality rate from PCI procedures was steady until 1995 and declined to the lowest level in 2004 regardless of gender and ethnicity, except for Asians. This may be attributed to the major improvements achieved in the management of patients before, during and after PCI. Increasing utilization of glycoprotein IIb/IIIa inhibitors has been shown to improve outcomes.^15–18 Smaller sheath size for coronary intervention may have been contributed to lower bleeding rates. Technical advancement in PCI equipments such as improvement in stent and balloon design with lower crossing profile may have contributed to lower procedural related complications.^19–21 Preloading with clopidogrel^22,33 and greater utilization of bivalirudin^24,25 in patients undergoing PCI procedures are other important factors that could have contributed to better PCI-related outcomes. Despite improving downward trends in PCI-related mortality, women and minorities had higher mortality rates in comparison to men or Caucasians during the entire study period. The cause of this disparity, which has been observed in many cardiovascular disease outcomes including MI-related mortality,^2,26 is not known. Women at the same age in comparison to men have higher comorbidities, which may explain our finding. In a large study adjusting for baseline characteristics, female gender was not associated with higher PCI-related mortality.¹³ Race-related mortality from PCI has not been studied previously. The reason for a higher persistent mortality rate in minorities is not known. Furthermore, we cannot explain the increasing trend toward PCI-related mortality in the Asian population, and thus warrants further investigation. Our study utilized administrative database with ICD-9 coding. This has inherent diagnostic inaccuracy limiting our data. We used primary diagnosis for PCI. However, we cannot exclude that PCI procedures were coded as the secondary procedure, thus not capturing all PCI cases. Changes in diagnostic coding over the years may have influenced the accuracy of our data. We did not have any data in regard to medications used during or after PCI, thereby limiting our results.

References

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From the ^*Division of Cardiology, The Southern Arizona VA Health Care System, Tucson, Arizona; the ^§Division of Cardiology, University of Arizona Sarver Heart Center, Tucson, Arizona; and ^†VA Long Beach Health Care System, Long Beach, California. The authors report no conflicts of interest regarding the content herein. Manuscript submitted August 13, 2009, provisional acceptance given September 8, 2009, final version accepted November 3, 2009. Address for correspondence: Mohammad-Reza Movahed, MD, PhD, Associate Professor of Medicine, The Southern Arizona VA Health Care System and University of Arizona Sarver Heart Center, 1501 North Campbell Avenue, Tucson, AZ 85724. E-mail: rmova@aol.com