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July 2016
Mitral valve disease in the United States: retrospective analysis of hospitalizations and surgical procedures using the National Inpatient Sample (World Congress on Heart Disease abstract)

Mark Stuntz
World Congress on Heart Disease
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a b s t r a c t

Introduction
Valvular heart disease (VHDs), of which the mitral valve is frequently implicated, are collectively responsible for more than 20,000 annual deaths in the United States and the economic burden on the public health system due to VHDs is estimated in the billions of dollars.

Objective
The aim of this study was to assess the number of mitral valve disease hospitalizations and surgical procedures in the United States during the period 2010-2013. 

Materials and Methods
Patient data were extracted from the Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample (NIS). The NIS is the largest publicly available all-payer inpatient healthcare database in the United States, containing a 20% stratified systematic random sample of discharges from all US community hospitals. The most recent 4 years of available data, 2010-2013, were used for this analysis. Patients diagnosed with mitral valve disease were identified using the appropriate International Classification of Diseases 9th revision (ICD-9) diagnosis codes. ICD-9 procedure codes were used to identify surgeries to repair or replace the mitral valve, including transcatheter mitral valve repair (TMVR), open repair, tissue graft, and synthetic replacement. Categorical variables were analyzed using the chi-squared test, while continuous variables were analyzed using a one-way analysis of variance (ANOVA) or independent samples t-test.

Results
There were 174,2587 discharge records in 2013 with a diagnosis of mitral valve disease. Using HCUP’s sampling weights, this extrapolates to 871,290 hospitalizations in the United States. This is a slight decrease from 2010, when there were 883,933 estimated hospitalizations. The mean age of patients hospitalized for mitral valve disease increased from 71.15 (95% CI: 71.08-71.23) years in 2010 to 71.68 (95% CI: 71.61-71.76) years in 2013 (p<0.0001). 61.7% of mitral valve hospitalizations were females in 2010 compared with 59.2% in 2013 (p<0.0001). Mitral valve surgical procedures increased from 35,111 procedures in 2010 to 38,030 procedures in 2013. Concurrently, the proportion of mitral valve disease patients that underwent a surgical procedure to repair or replace the mitral valve increased from 3.5% in 2010 to 3.9% in 2013 (p<0.0001). Among elderly patients ≥80 years of age, mitral valve disease represented an increasing proportion of all hospitalizations, increasing from 6.0% in 2010 to 6.6% in 2013. Patients with a primary diagnosis of mitral valve disease who underwent a mitral valve surgical procedure were younger on average than those with a primary diagnosis of mitral valve disease who did not undergo a surgical procedure: 64.50 (95% CI: 64.31-64.69) years vs. 70.73 (95% CI: 70.51-70.95) years (p<0.0001).

Conclusions
This study reveals that mitral valve disease is a considerable public health problem in the United States, particularly among older adults. During 2010-2013, an increasing proportion of hospitalized patients with mitral valve disease underwent surgical procedures to repair or replace the valve. Overall, the volume of mitral valve surgical procedures increased approximately 8.3% from 2010 to 2013.