Clinical Outcome Trends of Type B Aortic Dissections in South Carolina

Background: Aortic dissection is the most common pathology of the aorta. Stanford type B dissections are associated with significant morbidity and mortality. The goal of this study was to evaluate the incidence, treatment, and outcome trends for patients admitted to South Carolina hospitals with Stanford type B aortic dissections.
Methods: Utilizing CPT and ICD-9 codes to identify patients admitted with type B aortic dissection, the South Carolina Office of Research and Statistics (SCORS) database and the Greenville Hospital System Department of Surgery Vascular Database was interrogated with regard to medical comorbidities, length of stay, procedures performed, hospital readmissions, and in-hospital mortality. Age-adjusted incidence rates were calculated for each year and compared using a pooled population of all 11 years.
Results: From 1997 through 2007, 890 patients were admitted to hospitals in South Carolina with type B aortic dissections. Admissions for type B aortic dissections rose from 2.41 cases per 100,000 South Carolina adults in 1997 to 2.74 cases per 100,000 South Carolina adults (p=0.004) in 2007 representing a 14% increase. Reported comorbidities included hypertension, CAD, COPD, and tobacco abuse at 79%, 22.5%, 14.4%, and 6.4%, respectively. The average length of hospital stay was 7.8 days. Hospital cost per stay trended upward from $20,519 in 1997 to $112,268 in 2007 which represents a 547% increase. Twelve month in-hospital mortality averaged 20.5% over the period studied, ranging from13% in 2007 to 29% in 1998, not a significant trend (p=0.089). The trend in the number interventions per patient per year ranged from 0.13 interventions per patient in 2000 to 0.55 interventions per patient in 2007, averaging 0.35 interventions per patient per year (p=0.055). Of the 312 interventions performed over the time period studied, 47 (15.1%) were endovascular procedures. The proportion of open surgical interventions decreased from 1997 to 2007 (p<0.001) Of the endovascular procedures, 19 (40.4%) were endovascular aortic repairs, 18 (38.3%) were percutaneous transluminal angioplasty, and 10 (21.3%) were other percutaneously placed stents. At our institution, admissions for type B aortic dissections rose by 300% from 1997 to 2007. Comorbidities included hypertension, tobacco abuse, hyperlipidemia, and CAD at 98%, 54%, 44%, and 25% respectively. Our twelve month in-hospital mortality was 15.4%. We performed a total of 8 interventions on our 52 patients, 3 of which (37.5%) were endovascular.
Conclusion: The incidence of type B aortic dissection in South Carolina is increasing. The standard medical treatment of type B aortic dissection utilizing anti-impulse therapy has not changed appreciably over the years studied, however, there is a definitely an increasing trend toward utilizing endovascular therapy. Despite this, the overall survival has remained unchanged, and the cost has steadily increased. This study questions cost effectiveness of our current approach to aortic dissection and specifically the shift toward endovascular therapy to treat this challenging clinical problem.