Figure 2. Mortality at 30, 90, and 180 Days Stratified by Frailty and Number of Complications.

The categories of Operative Stress Score are defined as follows: 1, very low stress; 2, low stress; 3, moderate stress; 4, high stress; and 5, very high stress. The Risk Analysis Index (RAI) is based on the accumulation of deficits model of frailty and uses 14 variables to generate a score from 0 to 81, with higher scores indicating more frailty.