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.

Abstract 2746: Preclinical activity and manufacturing feasibility of genetically modified PDCD-1 knockout (KO) tumor-infiltrating lymphocyte (TIL) cell therapy

Background: Adoptive cell therapy with autologous TIL has demonstrated an objective response rate (ORR) of 36% in the post-immune checkpoint inhibitor (ICI) setting in patients (pts) with advanced/unresectable melanoma (Sarnaik JCO 2021), while in ICI-naïve pts who received early-line combination of TIL and pembrolizumab, the ORR was 60%, with a 30% CR rate (O’Malley SITC 2021). Although effective, anti-PD-1 therapy is limited by poor penetration into the tumor, internalization, and endocytic clearance, in contrast with TIL, which overcome this inherent limitation. PDCD-1 gene inactivation (PD-1 KO) may enhance TIL cell therapy efficacy in the post-ICI setting and abrogate the need for systemic anti-PD-1 therapy in ICI-naïve pts. In preclinical studies, PD-1 KO TIL maintain robust effector function and phenotypic markers indicative of functional TIL (Ritthipichai ESMO 2020). We describe preclinical activity, clinical-scale manufacturing process development, and characterization of IOV-4001, an autologous PD-1 KO TIL cell product.

Methods: hIL-2 NOG mice engrafted with melanoma tumor cells received adoptive transfer of autologous PD-1 KO TIL (developed with TALEN® gene editing technology in collaboration with Cellectis), mock TIL (electroporation without TALEN), mock TIL + anti-PD-1 antibody, or no adoptive transfer (n=14 each). Tumor size was measured 2×/wk for 39 days. A 22-day clinical-scale manufacturing process was established, including pre-rapid expansion protocol (pre-REP), activation, electroporation, resting, and REP, for the generation of PD-1 KO TIL. Final PD-1 KO TIL product was characterized for total viable cells (TVC), purity (% viability), identity (% CD45+CD3+), and function (PD-1 KO efficiency).

Results: Day 39 mean ± SEM tumor size (mm2) for mice treated with PD-1 KO TIL (6 ± 2.8) showed superior tumor control relative to mock TIL (26 ± 8.5, P<0.05), mock TIL + anti-PD-1 (33 ± 8.8, P<0.01), and no adoptive TIL transfer (112 ± 8.4, P<0.0001). Product attributes from 6 clinical-scale manufacturing runs for PD-1 KO TIL were acceptable, with a median (range) TVC, purity, and identity of 8.3 × 109 (0.9×109-35.7×109), 94% (91%-99%), and 99% (98%-99%), respectively. Median (range) PD-1 KO efficiency was 48% (31%-84%). PD-1 KO TIL function and phenotype (differentiation, memory, activation, and exhaustion) were comparable to mock TIL.

Conclusions: Anti-tumor activity of PD-1 KO TIL was superior to mock TIL suggesting that endogenous PD-1 inhibition may confer a functional advantage to the TIL over an antibody combination. PD-1 KO TIL clinical manufacturing was feasible and the TIL product quality attributes and phenotype were acceptable; importantly, lack of complete PD-1 KO may spare other PD-1-dependent in vivo cellular functions. Together, these data support clinical investigation of IOV-4001, an autologous PD-1 KO TIL cell therapy.

Citation Format: Arvind Natarajan, Anand Veerapathran, Adrian Wells, Kenneth Onimus, Marcus Machin, Seth Wardell, Jamie L. Blauvelt, Madan Jagasia, Rafael Cubas. Preclinical activity and manufacturing feasibility of genetically modified PDCD-1 knockout (KO) tumor-infiltrating lymphocyte (TIL) cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2746.

180 Systematic Review and Meta-Analysis of Exercise Therapy for Venous Leg Ulcer Healing and Recurrence

Aim

National guidelines recommend regular exercise for individuals with venous leg ulceration, yet data for the effect of exercise on ulcer healing and recurrence are sparse. This study aimed to quantify the evidence for exercise in venous ulcer healing with the primary outcomes of proportion of healed ulcers and rate of ulcer recurrence. Secondary outcomes were compliance and adverse events.

Method

The review followed PRISMA guidelines using a registered protocol (CRD42021220925). Medline, Embase and Cochrane Databases were searched on 15th March 2021 and included articles comparing exercise to compression therapy. Meta-analysis was performed to pool the data.

Results

After screening 994 articles, six reports were included with 109 participants allocated to exercise and 113 to compression. All articles were randomised-controlled trials and reported ulcer healing at 12 weeks, with a pooled relative risk of 1.35 ulcers for exercise versus compression (95% CI 1.07 – 1.71). Only one article reported on recurrence and data pooling was not performed, but no difference between exercise and usual care was demonstrated. Adverse events were inadequately reported and seen to be more frequent in the exercise arm. Compliance with exercise ranged from 33–81%.

Conclusions

There is increasing evidence for exercise as an adjunct to ulcer healing, however, trials were low quality with high risk of bias. This is a crucial innovation as many ulcers recur or fail to heal in spite of surgical correction of underlying venous insufficiency. There is paucity of evidence examining leg ulcer recurrence after exercise programmes and currently no evidence of benefit.

331 The Role of Prophylactic and Therapeutic Fasciotomy in Acute Limb Presentations

Introduction

Acute compartment syndrome is a surgical emergency that can be of traumatic or non-traumatic nature. Missed or delayed diagnosis can cause significant morbidity. The aim of this systematic review was to assess outcomes following prophylactic and therapeutic fasciotomies performed for acute limb presentations.

Method

This systematic review was undertaken following a predefined protocol registered with PROSPERO, in accordance with PRISMA guidelines. Searches of MEDLINE and Embase databases retrieved 623 articles; 19 articles were included in the study. A qualitative synthesis was performed due to heterogeneity between the studies.

Results

Overall mortality rates of 0–19 % were reported for traumatic causes and 24.5–27% for non-traumatic causes. In general, comparative studies reported lower amputation rates (0–21.7% vs 6.6–50%) and neurological deficit rates in the prophylactic versus therapeutic fasciotomy arms (8.8–18% vs 12.5–42%). Complication rates of up to 42% and 35% were reported in traumatic and non-traumatic cases respectively, which included wound infection, nerve injury and ischaemic contractures.

Conclusions

Prophylactic fasciotomies appear to have superior outcomes than therapeutic ones. There is insufficient evidence for a specific time cut-off for the performance of therapeutic fasciotomies; retrospective analysis of outcomes via a fasciotomy registry may help to guide future practice.

Systematic review of inframalleolar endovascular interventions and rates of limb salvage, wound healing, restenosis, rest pain, reintervention and complications

Objectives

Peripheral artery disease is estimated to affect 237 million individuals worldwide. Critical limb ischaemia, also known as chronic limb threatening ischaemia is a consequence of the progression of peripheral artery disease which occurs in ∼21% of patients over a five-year period. The aim of this systematic review is to assess the use of additional below-the-ankle angioplasty in comparison to the use of above-the-ankle angioplasty alone, and the subsequent rates of amputation, wound healing, restenosis, rest pain, reintervention and complications.

Methods

This systematic review was undertaken in accordance with PRISMA guidelines following a registered protocol (CRD42019154893). Online databases were searched using a search strategy of 20 keywords. Included articles reported the outcome for inframalleolar (pedal artery, pedal arch, plantar arteries) angioplasty with additional proximal angioplasty in comparison to proximal angioplasty alone. GRADE assessment was applied to assess the quality of the evidence.

Results

After screening 1089 articles, 10 articles met the inclusion criteria. Comparative performance assessment of below-the-ankle with above-the-ankle versus above-the-ankle angioplasty alone was undertaken in 3 articles, with the remaining 7 articles reporting outcomes of below-the-ankle with above-the-ankle angioplasty with no distinct comparator group. Significant decrease in major lower limb amputation at the last follow-up in the below-the-ankle group when compared with the above-the-ankle angioplasty alone group was observed in a single study (3.45% vs. 14.9%, p < 0.05). Improved wound healing rate at follow-up in the below-the-ankle group versus above-the-ankle angioplasty alone group was also reported in a single study (59.3% vs. 38.1%, p < 0.05). Subsequent rate of amputation after below-the-ankle angioplasty has been estimated as 23.5%.

Conclusion

To date, there is a lack of studies assessing inframalleolar interventions and their use in improving limb salvage, wound healing and symptomatology. Prospective RCTs should be undertaken with adequate participant numbers to be sufficiently powered and report clinically important end-points.

Surgical and non-surgical approaches in the management of lower limb post-thrombotic syndrome

Introduction: Post-thrombotic syndrome (PTS) is a common lifelong condition affecting up to 50% of those suffering from deep vein thrombosis (DVT). PTS compromises function and quality of life with subsequent venous ulceration in up to 29% of those affected.Areas covered: A literature review of surgical and non-surgical approaches in the prevention and treatment of PTS was undertaken. Notable areas include the use of percutaneous endovenous interventions and the use of graduated compression stockings (GCS) after acute proximal DVT.Expert opinion: In patients with acute iliofemoral DVT, we think it is important to have a frank conversation with the patient about catheter-directed thrombolysis, aiming to reduce the severity of PTS experienced. We advocate ultrasound-accelerated thrombolysis with adjunctive procedures, such as deep venous stenting for proximal iliofemoral DVT. For patients with isolated femoral DVT, we believe that anticoagulation and GCS should be recommended. In patients with established PTS, we recommend GCS for symptomatic relief. We recommend that patients engage in regular exercise where possible with the prospect of gaining symptomatic relief. For those with severe PTS that has a significant effect on quality of life, we discuss the patient's case at a multi-disciplinary team meeting to plan for endovenous intervention.

Systematic review on the management of ileoanal pouch-vaginal fistulas after restorative proctocolectomy in the treatment of ulcerative colitis

AIM

Ileoanal pouch-vaginal fistula (PVF) is a relatively common complication of restorative proctocolectomy with ileal pouch-anal anastomosis. There are several operative approaches in the management of PVF. There is currently no consensus as to which approach is the most effective or which should be attempted first.

METHOD

A systematic review was undertaken following a publicly available protocol registered with PROSPERO (CRD42019133750) in accordance with PRISMA guidelines. Online searches of databases MEDLINE and Embase, Cochrane Library, ClinicalTrials.gov, EU Clinical Trials and ISRCTN registry were performed.

RESULTS

Twenty-seven articles met the criteria for inclusion in the study: 13 retrospective cohort studies, two prospective cohort studies, eight case series, three case reports and a case-control study. A narrative synthesis was performed due to heterogeneity between included articles. Our study included 577 PVFs, and the incidence rate was 2.1%-17.1%. Both local and abdominal approaches were used in the management of PVF. The overall success of local and abdominal procedures was 44.9% and 60.2% respectively. ROBINS-I assessment revealed a critical risk of bias. GRADE assessment indicated a very low certainty in effect size and evidence quality.

CONCLUSION

Local interventions and abdominal approaches have a high failure rate. The results of this review will aid the counselling of patients with this condition. Furthermore, we provide an algorithm for discussion on the management of PVF based on experience at our local centre. The studies available on the management of PVF are low quality; a large prospective registry and Delphi consensus are required to further this area of research.

Systematic review on the benefit of graduated compression stockings in the prevention of venous thromboembolism in low-risk surgical patients

Objectives

The aim of this systematic review is to assess the performance of graduated compression stockings (GCS) in comparison to no venous thromboembolism (VTE) prophylaxis in the prevention of hospital-acquired thrombosis in low-risk surgical patients undergoing short-stay procedures.

Methods

Aligning with PRISMA guidelines, online databases MEDLINE and EMBASE, Cochrane Library® and trial registries were searched. Eligible articles reported the VTE rate in low-risk surgical patients either receiving GCS or no VTE prophylaxis.

Results

Narrative synthesis was performed on a single eligible article. The included study arm consisted of participants undergoing knee arthroscopy with the use of GCS alone reporting a total of 29 VTE events (4.4%), 16 of which were asymptomatic DVTs (2.4%).

Conclusion

There is a complete lack of evidence to support the use of GCS in the prevention of HAT for low-risk surgical patients. An adequately powered trial is required to provide level-IA evidence to support this practice.

A systematic review of the management of synthetic mesh erosion of the rectum following urogynaecological surgery

AIM

Synthetic rectal mesh erosion is a challenging complication following urogynaecological surgery. The aim of this study was to determine the optimal management of rectal mesh erosion following urogynaecological surgery.

METHOD

A systematic review was undertaken following a pre-defined protocol registered with PROSPERO (CRD42018112425) in accordance with PRISMA guidelines. Searches of MEDLINE online database, Cochrane Library and clinical trial registries (ClinicalTrials.gov, EU Clinical Trials, ISRCTN registry) were performed. The included articles were heterogeneous - therefore a narrative synthesis was performed.

RESULTS

Fourteen studies were included in the review: 11 case reports, one case series, one retrospective cohort and one prospective multicentre trial. Fourteen rectal mesh erosions were identified. Eight (57%) of the rectal erosions underwent major abdominal surgery. In two of these cases, the abdominal approach was used only after failure of the transanal route. Five (36%) of the mesh erosions were managed using a transanal approach. In one case, the mesh passed without intervention.

CONCLUSION

Synthetic rectal mesh erosion can be managed successfully via either a transanal or a transabdominal approach with a partial or complete excision of the mesh. An examination under anaesthetic with an attempted transanal removal of mesh should be considered the first step in the management of this condition before consideration of more invasive surgery.

Characterization of Platelet Adhesion under Flow using Microscopic Image Sequence Analysis

A method for quantitative analysis of platelet deposition under flow is discussed here. The model system is based upon perfusion of blood platelets over an adhesive substrate immobilized on a glass coverslip acting as the lower surface of a rectangular flow chamber. The perfusion apparatus is mounted onto an inverted microscope equipped with epifluorescent illumination and intensified CCD video camera. Characterization is based on information obtained from a specific image analysis method applied to continuous sequences of microscopical images. Platelet recognition across the sequence of images is based on a time-dependent, bidimensional, gaussian-like pdf. Once a platelet is located, the variation of its position and shape as a function of time (i.e., the platelet history) can be determined. Analyzing the history we can establish if the platelet is moving on the surface, the frequency of this movement and the distance traveled before its resumes the velocity of a non-interacting cell. Therefore, we can determine how long the adhesion would last which is correlated to the resistance of the platelet-substrate bond. This algorithm enables the dynamic quantification of trajectories, as well as residence times, arrest and release frequencies for a high numbers of platelets at the same time. Statistically significant conclusions on platelet-surface interactions can then be obtained. An image analysis tool of this kind can dramatically help the investigation and characterization of the thrombogenic properties of artificial surfaces such as those used in artificial organs and biomedical devices.

K+ Channel Activation Promotes Tumor infiltrating Lymphocyte (TIL) Expansion and Enhances Expression of CCR7

Only two K+ channels are known to be expressed by T-cells. Activated effector T cells express high levels of Kv1.3; activated naïve and central memory T-cell subsets express high levels of KCa3.1. Overexpression of Kv1.3 in murine T-cells increases K+ efflux, improves effector function (IFNγ production) and promotes anti-tumor activity1. Inhibition of KCa3.1 suppresses murine T-cell proliferation and cytokine production. In human PBMCs and TIL, KCa3.1 expression was relatively low with upregulation observed within 24 h following stimulation with anti-CD3 and anti-CD28. The addition of the KCa3.1 agonist SKA-31 did not alter KCa3.1 expression but enhanced CCR7 expression significantly on TIL and human PBMCs. TILs propagated in the Rapid Expansion Protocol (REP) had a 1.42-fold greater expansion (p=0.002) in the presence of SKA-31 and significant increases in the CD8+CD28+ (p=0.04), CD8+CD27+(p=0.04), and CD8+CD27+CD28+subsets (p=0.002), consistent with a less differentiated phenotype. We thus demonstrate that SKA-31 treatment enhances CCR7 expression associated with memory cells, promotes TIL expansion, and attenuates T-cell differentiation. Targeting the KCa3.1 channel is a novel strategy to expand and sustain less differentiated TILs and may improve the clinical application of adoptive T-cell therapy.

1: Eil R, Vodnala SK, Clever D, Klebanoff CA, Sukumar M, Pan JH, Palmer DC, Gros A, Yamamoto TN, Patel SJ, Guittard GC, Yu Z, Carbonaro V, Okkenhaug K, Schrump DS, Linehan WM, Roychoudhuri R, Restifo NP. Ionic immune suppression within the tumour microenvironment limits T cell effector function. Nature. 2016;537):539–543.

Affective instability prior to and after thoughts about self-injury in individuals with and at-risk of psychosis: a mobile phone based study

It has been proposed that affective instability may be associated with thoughts about self-injury. The aim of this study was to test the hypotheses that instability in feelings of depression, but not anxiety, guilt, or hostility, would predict greater concurrent and subsequent thoughts about self-injury. Thirty-six individuals with psychosis completed questions on touch-screen mobile phones at semi-random times each day for one week. The instability of depression predicted greater concurrent and subsequent levels of thoughts about self-injury, even when controlling for depression level. Conversely, self-injurious thoughts predicted more stable depression. The instability of guilt, anxiety, and hostility did not significantly predict levels of thoughts about self-injury. Results indicate that a variable depressive state may trigger the onset of thoughts about self-injury, which increases the risk of its subsequent recurrence. The onset of self-injurious thoughts may, however, have a stabilizing effect on subsequent depression.

A quality assurance programme for cell salvage in cardiac surgery

At the same time as cell salvage was introduced into our institution for all patients undergoing cardiac surgery with cardiopulmonary bypass, we established a supporting programme of quality assurance to reassure clinicians regarding safety and efficacy. Data collected in patients operated on between 2001 and 2007 included pre- and post-wash heparin concentration, haemoglobin concentration and free haemoglobin concentration. Cell salvage was used in 6826 out of a total of 7243 patients (94%). Post-wash heparin concentration was consistently low (always < 0.4 IU.ml(-1)). There was a significant decrease in post-wash haemoglobin concentration in 2003 compared to 2001, from a median (IQR [range]) of 19.6 (16.7-22.2 [12.9-25.5]) g.dl(-1) to 17.5 (13.6-20.8 [12.6-23.7]) g.dl(-1) (p < 0.015). In addition, there was a significant increase in free plasma haemoglobin in 2006 compared to 2001, from 0.5 (0.3-0.8 [0.1-2.6]) g.l(-1) to 0.8 (0.3-1.4 [0.3-5.2]) g.l(-1) (p < 0.001). This programme led to the detection of a change in operator behaviour in 2003 and progressive machine deterioration resulting in appropriate fleet replacement in 2006. You can respond to this article at http://www.anaesthesiacorrespondence.com.

Quantitative tissue characterisation in pancreatic disease using magnetic resonance imaging

Twenty-nine patients, 27 of whom had either inflammatory disease of the pancreas or pancreatic tumour, were studied by magnetic resonance imaging (MRI) and computed tomography (CT). Six healthy volunteers were studied by MRI alone. The pancreatic T1 and T2 relaxation times were calculated using a multipoint iterative method with data from seven total saturation recovery and six spin echo sequences. Magnetic resonance imaging can demonstrate the normal pancreas and a variety of pathological processes greater than 1-2 cm in size, but with less spatial resolution than CT. The relaxation-time results indicated no significant discrimination between chronic pancreatitis and pancreatic tumour. A significant elevation in the relaxation times was observed, however, in those patients with calcific chronic pancreatitis compared with the non-calcific chronic pancreatitic group and normal controls, suggesting a different pathophysiology for the two subgroups of chronic pancreatitis. The active phase of acute pancreatitis was associated with significantly elevated relaxation times, which returned to normal levels during the resolved phase of the disease. Associated extrapancreatic fluid collections were characterised by their very long relaxation times. The problems associated with spatial resolution, respiratory motion and lack of quantitative tissue characterisation suggest that MRI of the pancreas, using present methods, is unlikely to contribute to the overall management of patients with exocrine pancreatic disease.

MR imaging of the intervertebral disc: a quantitative study

The T1 and T2 relaxation times and the proton density of the nucleus pulposus have been measured in 107 normal and 18 surgically proven degenerate intervertebral discs. Data from total saturation recovery and spin echo sequences have been utilised in a robust multi-point method and relaxation times and proton density calculated. The results show that both the T1 and T2 values of the normal nucleus pulposus decrease with age. There was no significant correlation between proton density and age in normal discs. At all ages there was a highly significant difference between the T1 values of normal and degenerate discs. With T2 a highly significant difference in the younger age groups reduced to no distinction in the seventh decade. The observed change in the T1 and T2 values of the nucleus is in agreement with the reduction of water content known to occur with age. Our results indicate that quantitative MR imaging may assist in the diagnosis of intervertebral disc degeneration.