We investigated the incidence and characteristics of 14,996 patients with aortic stenosis (AS) who were hospitalized in New Jersey between the years 1995 to 2015. The average age was 72, the majority were Caucasian males and common co-morbidities were hypertension, coronary artery disease and hypercholesterolemia. Hospital admission for AS declined between 1995 to 2007, to 10/100,000 patients, and increased to 15/100,000 patients in 2015 (p for trend <0.001). During the study period, the percentage of patients who received aortic valve replacement (AVR) increased (p <0.001). All-cause and cardiovascular mortality were higher among patients who did not undergo AVR at 1-year (HR 1.98 CI 1.75 to 2.23, p <0.001 and HR 1.82 CI 1.57 to 2.11, p <0.001, respectively) and 3-years (HR 2.16 CI 1.96 to 2.38, p <0.001 and HR 2.16 CI 1.90 to 2.45, p <0.001, respectively). The probability for readmission for AS was higher in patients who did not receive AVR compared to patients who had AVR at 1 year (HR 92.95 CI 57.85 to 149.35, p <0.001) and 3 years (HR 70.36 CI 47.18 to 104.95, p <0.001). These data imply that earlier diagnosis of AS and AVR when indicated will improve outcomes.
Aortic stenosis (AS) is the most common valvular disease in developed countries, and its impact on healthcare utilization will increase as a result of the aging of the population. The estimated prevalence of AS among persons older than 75 is 12.4%, and severe AS is present in 3.4% , , in this age group. Previous studies have shown a rising trend in hospitalizations of patients with aortic valve disease as well as an increase in the prevalence of the disease. , , , There are knowledge gaps on the population-based prevalence, demographics and management of AS and how these have changed in recent years with the continued evolution of the treatment and diagnosis of AS. Furthermore, as the management strategies of AS continues to evolve, more evidence is required in order to determine the optimal timing of intervention for patients with AS. The goal of this investigation is to examine the prevalence of AS hospitalizations, surgical management, morbidity, mortality and the risk of hospital re-admission for myocardial infarction, cerebrovascular accident and heart failure in New Jersey for the years 1995 to 2015. We also aimed to identify differences in outcomes of AS patients who underwent aortic valve replacement (AVR) or did not have a surgical procedure. Data were obtained from the Myocardial Infarction Data Acquisition System (MIDAS) that includes all hospitalizations for cardiovascular (CV) disease in New Jersey with longitudinal follow up for up to 30 years.
Methods
This study was conducted using the MIDAS data repository that includes information on all patients admitted to non-federal hospitals in NJ from 1995 to 2015. The study included men and women, aged 18 years and older, with a primary diagnosis of AS defined by International Classification of Diseases, Ninth Revision codes 395.0, 395.2, 424.1, and 746.3. Co-morbid conditions were identified using the following International Classification of Diseases, Ninth Revision codes: coronary artery disease (CAD) (414.00-414.9), hypertension (HTN) (401.00, 401.1, 401.9, 402.00, 402.01, 402.10, 402.90, 403.00, 403.01, 403.10, 403.11, 403.90, 403.91), hyperlipidemia (HLD) (272.00-272.9), diabetes mellitus (DM) (250.00-250.93), congestive heart failure (HF) (428.00-428.9), myocardial infarction (MI) (410.01-410.91), cerebrovascular accident (CVA) (430.00-436.00, 997.02), cancer (199.00-199.2), anemia (285.00-285.9), liver disease (573.00-573.9), chronic kidney disease (CKD) (585.1-585.9), chronic obstructive pulmonary disease (COPD) (490.00-496.00), cardiomyopathy (425.00-425.9) and coronary artery bypass graft (CABG) (36.10-36.19). Patients with valvular disorders other than AS and patients who underwent transcatheter aortic valve replacement (TAVR) prior to or during the first AS admission were excluded from the analysis. The patients who underwent TAVR during first AS admission were excluded due to methodological drift.
Trend analysis on the incidence rate of hospitalized AS per 100,000 NJ residence was analyzed by fitting a piecewise linear model and assessing the slope and breakpoint for statistical significance. Trend analysis on the rate of AVR during hospitalization by year was done by fitting a logistic regression model with admission year as a continuous variable, adjusting for demographics (age, sex, race, Hispanic ethnicity, and insurance type) and comorbid conditions including cancer, CAD, DM, HTN, anemia, liver disease, CKD, CVA, HF, HLD, MI, COPD, cardiomyopathy and CABG. Differences in demographics and comorbid conditions between those receiving AVR and those who did not have AVR surgery were evaluated using chi-squared test for categorical variables and t-test for continuous variables. AVR surgery includes only surgical AVR and not TAVR.
Study outcomes included 1 and 3 years all-cause and CV case fatality and re-hospitalization for AS, HF, CVA or MI for patients who underwent AVR and those who did not. Also, differences in death during hospitalization between patients with AVR and those who did not have surgery for AS were assessed using logistic regression adjusting for demographics, comorbidities, and admission year. Kaplan-Meier curves for those with and without AVR were generated for both re-hospitalization at 1 and 3 years and survival at 1 and 3 years and compared through the log-rank test and cox proportional hazard models adjusting for demographics, comorbidities, and stratifying by admission year.
For the analysis of 1 and 3 year all cause and CV case fatality the start times for Kaplan-Meier curves for patients that received AVR was the procedure date. A cox model that included demographics and comorbid conditions as variables was used to generate a starting time for patients without AVR to make them more comparable to patients who received AVR. The cox model was fit on those who received AVR, where the response was time from admission to procedure in days, and a procedure curve for individuals who did not receive AVR was generated. The starting time for individuals without AVR was then generated by taking the inverse value of the procedure curve at the value of a randomly drawn uniform random variable.
Results
Patients with a first hospitalization of AS as the primary discharge diagnosis (n = 14,996) who did not have an additional valve disease were identified during the study period. The mean age of the AS patients was 72 years, and the majority of patients had Medicare as their primary healthcare insurance. The majority of patients were Caucasian and male ( Table 1 ). The most common co-morbid conditions were HTN, CAD, and HLD. Patients who underwent AVR were more likely to have CAD, CKD, cancer, HF, HLD, and COPD as compared to those who underwent no surgical procedure for AS. Patients who did not undergo AVR (mean age approximately 75 years old) were more likely to be older than patients who underwent AVR (mean age approximately 70 years old). A decline in the incidence of AS admissions was noted from the inception of the study and a statistically significant increase in the incidence of AS admissions was identified in 2007 from 10.0/100,000 to 14.6/100,000 in 2015 (p <0.001) ( Figure 1 ). The percentage of patients who received AVR overall increased during the 20-year study period ( Figure 2 ). Of the patients with AS with primary hospital discharge diagnosis, the majority of procedures including AVR, valvuloplasty, CABG and PCI were performed during the first hospitalization for AS.
| Variable | Combined (n = 14,996) | No AVR (n = 5,626) | AVR (n = 9,370) | p Value |
|---|---|---|---|---|
| Mean Age (SD) in Years | 72.0 (12.9) | 74.9 (14.1) | 70.2 (11.8) | <0.001 |
| White | 13,029 (86.8%) | 4,667 (83.0%) | 8,049 (85.9%) | <0.001 |
| Black | 882 (5.8%) | 452 (8.0%) | 414 (4.4%) | <0.001 |
| Other | 1,436 (9.6%) | 507 (9.0%) | 907 (9.7%) | 0.185 |
| Hispanic | 2,312 (15.4%) | 1,057 (18.8%) | 1,255 (13.4%) | <0.001 |
| Commercial Insurance | 5,152 (34.4%) | 1,575 (28.0%) | 3,577 (38.2%) | <0.001 |
| Medicaid | 198 (1.3%) | 100 (1.8%) | 98 (1.1%) | <0.001 |
| Medicare | 9,225 (61.5%) | 3,801 (67.6%) | 5,424 (57.9%) | <0.001 |
| Self-Pay | 421 (2.8%) | 150 (2.7%) | 271 (2.9%) | 0.447 |
| Men | 8,437 (56.3%) | 2,766 (49.2%) | 5,671 (60.5%) | <0.001 |
| Cancer | 1,981 (13.2%) | 832 (14.8%) | 1,149 (12.3%) | <0.001 |
| Coronary Artery Disease | 8,167 (54.5%) | 2,659 (47.3%) | 5,508 (58.8%) | <0.001 |
| Diabetes Mellitus | 3,760 (25.1%) | 1,379 (24.5%) | 2,381 (25.4%) | 0.226 |
| Hypertension | 10,315 (68.8%) | 3,876 (68.9%) | 6,439 (68.7%) | 0.837 |
| Anemia | 4,927 (32.9%) | 1,408 (25.0%) | 3,519 (37.6%) | <0.001 |
| Liver Disease | 157 (1.0%) | 72 (1.28%) | 85 (0.9%) | 0.037 |
| Chronic Kidney Disease | 1,224 (8.2%) | 586 (10.4%) | 638 (6.8%) | <0.001 |
| Cerebrovascular Accident | 1,899 (12.7%) | 809 (14.4%) | 1,090 (11.6%) | <0.001 |
| Heart Failure | 5,103 (34.0%) | 2,003 (35.6%) | 3,100 (33.1%) | 0.002 |
| Hyperlipidemia | 6,364 (42.4%) | 1,970 (35.0%) | 4,394 (46.9%) | <0.001 |
| Myocardial Infarction | 1,117 (7.5%) | 441 (7.8%) | 676 (7.2%) | 0.168 |
| Chronic Obstructive Pulmonary Disease | 2,825 (18.8%) | 1,141 (20.3%) | 1,684 (18.0%) | 0.001 |
| Cardiomyopathy | 682 (4.5%) | 292 (5.2%) | 390 (4.2%) | 0.004 |
| Coronary Bypass | 3,937 (26.3%) | 74 (1.3%) | 3,863 (41.2%) | <0.001 |
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