Long-term risk prediction after major lower limb amputation: 1-year results of the PERCEIVE study

Abstract

Background: Decision-making when considering major lower limb amputation is complex and requires individualized outcome estimation. It is unknown how accurate healthcare professionals or relevant outcome prediction tools are at predicting outcomes at 1-year after major lower limb amputation.

Methods: An international, multicentre prospective observational study evaluating healthcare professional accuracy in predicting outcomes 1 year after major lower limb amputation and evaluation of relevant outcome prediction tools identified in a systematic search of the literature was undertaken. Observed outcomes at 1 year were compared with: healthcare professionals' preoperative predictions of death (surgeons and anaesthetists), major lower limb amputation revision (surgeons) and ambulation (surgeons, specialist physiotherapists and vascular nurse practitioners); and probabilities calculated from relevant outcome prediction tools.

Results: A total of 537 patients and 2244 healthcare professional predictions of outcomes were included. Surgeons and anaesthetists had acceptable discrimination (C-statistic = 0.715), calibration and overall performance (Brier score = 0.200) when predicting 1-year death, but performed worse when predicting major lower limb amputation revision and ambulation (C-statistics = 0.627 and 0.662 respectively). Healthcare professionals overestimated the death and major lower limb amputation revision risks. Consultants outperformed trainees, especially when predicting ambulation. Allied healthcare professionals marginally outperformed surgeons in predicting ambulation. Two outcome prediction tools (C-statistics = 0.755 and 0.717, Brier scores = 0.158 and 0.178) outperformed healthcare professionals' discrimination, calibration and overall performance in predicting death. Two outcome prediction tools for ambulation (C-statistics = 0.688 and 0.667) marginally outperformed healthcare professionals.

Conclusion: There is uncertainty in predicting 1-year outcomes following major lower limb amputation. Different professional groups performed comparably in this study. Two outcome prediction tools for death and two for ambulation outperformed healthcare professionals and may support shared decision-making.

Fig. 1

Flow diagram of patients in the study PERCEIVE, PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE study.

Fig. 2

Receiver operating characteristic curves for healthcare professionals (a) and outcome prediction tools (b); and calibration curves for healthcare professionals (c) and outcome prediction tools (d) in predicting 1-year death after major lower limb amputation AKA, above knee amputation; BKA, below knee amputation; TKA, through knee amputation; NZRISK-VASC, The New Zealand Vascular Surgical Risk Tool; NZRISK, The New Zealand Surgical Risk Tool.

Fig. 3

Receiver operating characteristic curves for healthcare professionals (a) and outcome prediction tools (b); and calibration curves for healthcare professionals (c) and outcome prediction tools (d) in predicting 1-year major lower limb amputation revision after major lower limb amputation AKA, above knee amputation; BKA, below knee amputation.

Fig. 4

Sensitivity analyses comparing healthcare professionals (HCP) using an outcome prediction tool to inform predictions with those not using an outcome prediction tool a receiver operating characteristic curve for anaesthetists using/not using a tool to predict death. b receiver operating characteristic curve for allied healthcare professionals using/not using a tool to predict ambulation. c calibration curve for anaesthetists using/not using a tool to predict death.