3.1. Time trends in utilization, mortality, cost, and LOS among BiVAD patients
Between 2009 and 2015, there was an overall decline in the utilization of all BiVADs (-4.8% per year, p < 0.001, see Figure 1). There was a significant increase in the use of internal BiVADs (+10.0% per year, p < 0.001, see Figure 1) and a significant decrease in the use of external BiVADs (-9.4% per year,p < 0.001, see Figure 1). There were no significant changes in mortality for all BiVADs, internal BiVADs, or external BiVADs (see Appendix A). The costs associated with BiVAD implantation increased significantly (+23.0% per year, p <0.001). The LOS also had an increasing trend, although not significant (p = 0.083, see Figure 2). Among complications associated with BiVAD implantations, the rates of hemoperitoneum (p = 0.003), gastrointestinal (GI) bleed (p = 0.001), and acute renal failure (p = 0.008) increased significantly over time (see Table 2). Among known comorbidities, CAD (p = 0.006), MI (p = 0.010), fluid and electrolyte disorders (p = 0.043), and history of renal failure (p = 0.011) increased over time (see Table 2).