Evaluating the Prognostic Accuracy of AMPREDICT in Predicting 1-Year Mortality Following Major Lower Limb Amputation.

BACKGROUND

Accurately predicting postoperative outcomes is fundamental to informed clinical decision-making, and alignment of patient and family expectations. The AMPREDICT Decision Support Tool is a predictive tool designed to assess the probability of mortality 1 year after major and minor amputations. We aimed to evaluate the prognostic accuracy of AMPREDICT in our Veteran patient population.

METHODS

Retrospective review of lower extremity amputations completed at the West Los Angeles Veterans Affairs hospital from 2000 to 2020. Staged open amputations and previous minor amputations were excluded. Using the AMPREDICT tool, the probability of mortality 1 year postsurgery for single-stage transfemoral and transtibial amputations was calculated, then compared with observed patient outcomes. Observed to predicted mortality was compared through boxplots, at 1 year after surgery, confidence intervals were calculated, and group means were compared using Student's t-test. Receiver operator curves were constructed to assess discriminatory capacity of the tool. Significance was set at P < 0.05.

RESULTS

Four hundred twenty three patients underwent 650 lower extremity amputations during our study period. Two hundred sixty seven patients underwent single-stage transfemoral or transtibial amputations comprising our study cohort. The average age at amputation was 66 years with an average age of death at 71 years. AMPREDICT tool's prognostic capability varied across the 2 amputations studied. For single-staged transfemoral amputations, prediction aligned closely with observed outcomes, as indicated by a significant P value of 0.0002 (confidence interval 12.73-36.37). For single-stage transtibial amputations, the predictions were also significant, P value 0.0017 (confidence interval 5.25-21.20), although had a wider prediction range.

CONCLUSIONS

Our study confirms the reliability of the AMPREDICT tool in predicting 1-year mortality for patients undergoing major lower limb amputations. The predictive accuracy was found to be statistically significant for both single-staged transfemoral and transtibial amputations. These findings suggest that AMPREDICT may be a valuable tool in the clinical setting for patients undergoing major lower limb amputation.