The PIII CLI risk score (previously published) is a simple tool for estimating AFS in CLI patients considered for infrainguinal bypass (IB). The current study sought to validate this risk stratification model using the prospective Vascular Study Group of Northern New England (VSGNNE) database.
Method
We calculated the PIII CLI risk score for 1579 patients receiving IB by 59 surgeons at 11 hospitals. Each patient's score (dialysis 4 pts, tissue loss 3 pts, age≥75 2 pts, CAD 1 pt) was calculated to stratify patients into low (≤3 pts), med (4-7 pts), and high (≥8 pts) risk categories. Baseline hematocrit was not included due to a large proportion of missing values. Kaplan-Meier method was used to calculate AFS for the 3 risk groups. Log rank test was used for intergroup comparisons. To assess validation, comparison to the PIII derivation and validation sets was performed.
Result
Stratification of the VSGNNE patients by risk category yielded three significantly different estimates for 1-year AFS (84.7%, 73.5%, and 54.5%, for low, med, and high risk groups, Fig). Intergroup comparison demonstrated precise discrimination (p<.0001). For a given risk category (low, med, high), the 1-year AFS estimates were consistent between the VSGNNE dataset and the PIII derivation set (85.9%, 73.0%, 44.6%), PIII validation set (87.7%, 63.7%, 45.0%), and the retrospective validation set (86.3%, 70.1%, 47.8%) (Fig).
The PIII CLI risk score has now been tested in 3699 CLI patients at 94 institutions by a diverse array of physicians. This tool provides a simple and reliable method to risk stratify CLI patients being considered for IB. At initial consultation, patients with a 50% chance of death or major amputation at 1 year can be identified.
1University of Massachusetts Medical School, Worcester, MA
FULL TEXT
00392-9/journalimage?img=PIIS0741521409003929.gr1.lrg.gif&fig=fig1&kwhquery=&issn=0741-5214&ishighres=false&allhighres=false&free=yes','journalimage');)
