Figure 4.

Difference in mean annual hospital costs from baseline cost in pre/post within-individual analyses in the 5-year period after discharge from index hospitalization: sensitivity analysis in varying baseline hospital cost and effect of aging on hospital costs. (A) Baseline hospital cost was varied from the mean annual hospital cost in the 1 year before index hospital admission (solid lines) and the mean annual hospital cost in the 5 years before index hospital admission (dashed lines). Lighter lines represent 95% confidence intervals. (B) In addition to varying baseline costs, the effect of aging on hospital costs was modeled, using the gradient of increasing costs during the preindex hospitalization period. The gradient was assumed to vary under three scenarios: no effect of aging on costs (X); the assumption that the cost gradient during Years –5, –4, and –3 pre–index hospitalization continued during Years 0 to 5 years posthospitalization (Y); and finally, the assumption that the cost gradient from –5 years to 0 years pre–index hospitalization continued during Years 0 to 5 years posthospitalization (Z).