Figure 1.

Framework for Functional Decline, Recovery, and Resilience. Following exposure to a stressor, patients decline from an initial level of function to a nadir, then recover. Resistance can be defined as the extent of functional loss to the nadir. Reserve can be defined as the distance between initial function and the point of no return. Resilience can be defined as the degree to which post-recovery function matches initial function. In some cases, patients can decline to a point of no return, leading to permanent disability or death.