Figure 2.

Comorbidity and illness burden correlate with increasing complication rates. A) The mean comorbidity score has increased over time from an average 1.25 per patient in 2002 to 2.29 in 2011. B) The overall in-hospital complication rate has also increased over time from 4.5% in 1998 to 12.7% in 2011. (red) Mortality rate over this same period has remained stable from 2.29% in 1998 to 2.79% in 2011. (blue) C) Illness burden predictors of disease severity (red) and pre-operative mortality risk predictors (blue), which were also initiated in the NIS database beginning in 2002, have also increased from 1.9 and 1.51 respectively in 2002 to 2.45 and 2.21 in 2011.