The GermanVasc Score: A Pragmatic Risk Score Predicts Five Year Amputation Free Survival in Patients with Peripheral Arterial Occlusive Disease

Objective: Patients with peripheral arterial occlusive disease (PAOD) face an increased risk of both lower limb amputation and death. To date, it has been challenging to predict the long term outcomes for PAOD. The aim was to develop a risk score to predict worse five year amputation free survival (AFS). Methods: In this retrospective analysis of claims data, symptomatic PAOD patients were split into training and validation sets. Variables in the model were patient age and sex, Elixhauser comorbidities, and the 190 most common secondary diagnoses. Penalised Cox regression (least absolute shrinkage and selection operator [LASSO]) with tenfold cross validation for variable selection was performed and patients were categorised into five risk groups using the ten most important variables. All analyses were stratified by intermittent claudication (IC) and chronic limb threatening ischaemia (CLTI). Results: In total, 87 293 patients with PAOD (female 45.3%, mean age 71.4 +/- 11.1 years) were included in the analysis. The most important variable predicting worse five year AFS was patient age >80 years. The GermanVasc score exhibited good predictive accuracy both for IC (c statistic = 0.70, 95% confidence interval [CI] 0.69-0.71) and CLTI (c statistic = 0.69, 95% CI 0.68-0.70) with adequate calibration due largely to alignment of observed and expected risk. Depending on the cumulative point score, the five year risk of amputation or death ranged from 9% (low risk) to 48% (high risk) for IC, and from 25% to 88% for CLTI. Conclusion: The GermanVasc score predicts worse five year AFS stratified for inpatients suffering from IC and CLTI, with good predictive accuracy. By separating low from high risk patients, the GermanVasc score may support patient centred consent.