INCIDENCE OF AORTIC STENOSIS IN OBESE PATIENTS: AN ANALYSIS USINF THE NIS DATABASE
BACKGROUND/INTRODUCTION: Aortic Valve Stenosis is a thickening and/or calcification of the aortic valve which leads to Left Ventricular Hypertrophy and subsequent increased left ventricular pressures. This eventually gives rise to a number of complications, the most notable being Congestive Heart Failure. The standard of care in management of Aortic Valve Stenosis is Aortic Valve Replacement, by way of Surgical Aortic Valve Replacement (SAVR) or Transcatheter Aortic Valve Replacement (TAVR). Aortic Valve Stenosis has been associated with a number of factors (coronary artery disease, advanced age, diabetes mellitus, etc.), but its direct associations with obesity remain unclear.
STUDY PURPOSE: This study uses the National Inpatient Sample (NIS) database to assess the relationship between aortic stenosis (AS) and obesity.
METHODS: NIS database for years 2012 through 2014 was used. The incidence of AS was estimated using ICD-9 codes related to AS as a proxy. These codes were divided into surgical and percutaneous AS-related procedures. The incidence of these AS-related codes were then compared across BMI (BMI 25-30 and 30+) and age (Age <60 and 60+). Logistic regression models were used to predict percutaneous procedure, surgical procedure or both percutaneous and surgical. Percutaneous and surgical procedures were analyzed separately since surgery is typically not recommended for obese patients. Age groups were analyzed separately to differentiate AS resulting from congenital causes, which present most commonly before age 60, from AS resulting from acquired causes.
RESULTS: The analysis found that BMI, age, gender, income and bicuspid aortic stenosis are significant predictors of surgical AS-related procedure. Patients with BMI of 25-29 are 2.32 (2.05, 2.63) times more likely to undergo an AS-related surgical procedure than those with no recorded BMI, and are more likely to undergo an AS-related surgical procedure than those with BMI 30+ who are 2.00 (1.95, 2.05) times more likely to undergo an AS-related surgical procedure than those with no recorded BMI. Patients age 60+ are 4.93 (4.82, 5.05) times more likely to have a surgical AS-related procedure. The AS-related surgical procedure model including BMI, age, bicuspid aortic stenosis, gender, and income is correct nearly 75% of the time (AUC=0.745). The estimates for the odds of percutaneous AS-related procedure does not significantly differ for BMI 25-29 and 30+. Those who are 60+ are 15.49 (14.48, 16.57) times more likely to undergo a percutaneous procedure.
DISCUSSION/CONCLUSION: These findings suggest that obesity is associated with an increased risk of AS, as estimated by the increased incidence of both surgical and percutaneous AS procedures in obese patients. This is unsurprising, as many of the risk factors associated with obesity are also associated with AS. However, this relationship may have some utility as a clinical and decision-making tool in establishing a differential or performing workup related to AS. There are several limitations to this study, including the nature of the data itself (ICD codes as proxies for study parameters and outcomes), a substantial number of data missing information related to BMI (which might produce bias), and limited ability to control for known confounds. Nonetheless, establishing such a relationship is a necessary first step in our understanding of how obesity and aortic stenosis are related, and opens the door for further inquiry.