Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

Developmental changes in plasma angiotensin-converting enzyme concentration in fetal and neonatal lambs

Relationships between plasma angiotensin-converting enzyme (ACE) and cortisol, and blood pressure were examined in chronically catheterized ewes and their fetuses during late gestation (111-141 days, term 145 +/- 2 days). Plasma ACE was also measured in non-pregnant adult ewes and in lambs over the first 5 weeks of life. In fetuses near term (136-141 days), plasma ACE was greater than in those studied earlier in gestation; overall, plasma ACE correlated with gestational age (r = 0.72). The ontogenic rise in plasma ACE was associated with prepartum increases in plasma cortisol (r = 0.67) and blood pressure (r = 0.66). No relationship was observed between plasma ACE and partial pressure of oxygen in utero. Peak plasma ACE concentration observed in fetuses near term was maintained in newborn lambs for 3 days after birth. By 2 weeks of postnatal age, plasma ACE had decreased to the value seen in non-pregnant adult ewes. Maternal plasma ACE was similar at all gestational ages studied, and was lower than that observed in non-pregnant ewes. Therefore, in the sheep fetus, plasma ACE increased towards term in association with the prepartum cortisol surge. Developmental changes in ACE activity may be partly responsible for the ontogenic rise in fetal blood pressure.