3.2. Time trend analysis for cost and LOS among BiVAD patients: the survivors versus deceased
To explain the increase in cost and LOS among BiVAD patients despite no changes in mortality, a time trend analysis was performed. Stratification based on internal vs. external BiVADs demonstrated no significant time trends in cost and LOS for either internal or external BiVADs. Stratification based survival of the index hospitalization demonstrated no significant time trend in LOS or cost among those that survived, however, there was a significant and sizeable increase in LOS (+52.0% per year, p = 0.002, see Figure 2), as well as cost (+15% per year, p < 0.001, see Figure 3) among those that died. After controlling for known complications and comorbidities outlined in Table 2, LOS (+3.8% per year, p = 0.025) and cost (+$33,736 per year, p = 0.002) increased significantly over time among the patients who died during their hospitalization.