A goal-driven modular neural network predicts parietofrontal neural dynamics during grasping.

One of the primary ways we interact with the world is using our hands. In macaques, the circuit spanning the anterior intraparietal area, the hand area of the ventral premotor cortex, and the primary motor cortex is necessary for transforming visual information into grasping movements. However, no comprehensive model exists that links all steps of processing from vision to action. We hypothesized that a recurrent neural network mimicking the modular structure of the anatomical circuit and trained to use visual features of objects to generate the required muscle dynamics used by primates to grasp objects would give insight into the computations of the grasping circuit. Internal activity of modular networks trained with these constraints strongly resembled neural activity recorded from the grasping circuit during grasping and paralleled the similarities between brain regions. Network activity during the different phases of the task could be explained by linear dynamics for maintaining a distributed movement plan across the network in the absence of visual stimulus and then generating the required muscle kinematics based on these initial conditions in a module-specific way. These modular models also outperformed alternative models at explaining neural data, despite the absence of neural data during training, suggesting that the inputs, outputs, and architectural constraints imposed were sufficient for recapitulating processing in the grasping circuit. Finally, targeted lesioning of modules produced deficits similar to those observed in lesion studies of the grasping circuit, providing a potential model for how brain regions may coordinate during the visually guided grasping of objects.

Socioeconomic disparities in abdominal aortic aneurysm repair rates and survival.

BACKGROUND: Abdominal aortic aneurysm (AAA) is more prevalent in socioeconomically disadvantaged areas. This study investigated socioeconomic disparities in AAA repair rates and survival. METHODS: The study used ecological and cohort study designs, from 31 672 census areas in England (April 2006 to March 2018), the Index of Multiple Deprivation 2010 as the area-level deprivation indicator, and Poisson, logistic and Cox regression. RESULTS: Some 77 606 patients (83.4 per cent men) in four age categories (55-64, 65-74, 75-84, 85 or more years) were admitted with AAA from a population aged at least 55 years of 14.7 million. Elective open and endovascular repair rates were 41 (95 per cent c.i. 23 to 61) and 60 (36 to 89) per cent higher respectively among men aged 55-64 years in the most versus least deprived areas by quintile. This differences diminished and appeared to reverse with increasing age, with 26 (-1 to 45) and 25 (13 to 35) per cent lower rates respectively in men aged 85 years or more in the most deprived areas. Men admitted from more deprived areas were more likely to die in hospital without aneurysm repair. Among those who had aneurysm repair, this was more likely to be for a ruptured aneurysm than among men from less deprived areas. For intact aneurysm repair, they were relatively more likely to have this during an emergency admission. The mortality rate after repair was higher for men from more deprived areas, although the hazard diminished with age. Patterns were unclear for women. CONCLUSION: There were clear socioeconomic disparities in operation rates, mode of presentation, and outcome for AAA surgery. Policies are needed to address these disparities.

Value assessment frameworks: who is valuing the care in healthcare?

Many healthcare agencies are producing evidence-based guidance and policy that may determine the availability of particular healthcare products and procedures, effectively rationing aspects of healthcare. They claim legitimacy for their decisions through reference to evidence-based scientific method and the implementation of just decision-making procedures, often citing the criteria of 'accountability for reasonableness'; publicity, relevance, challenge and revision, and regulation. Central to most decision methods are estimates of gains in quality-adjusted life-years (QALY), a measure that combines the length and quality of survival. However, all agree that the QALY alone is not a sufficient measure of all relevant aspects of potential healthcare benefits, and a number of value assessment frameworks have been suggested. I argue that the practical implementation of these procedures has the potential to lead to a distorted assessment of value. Undue weight may be ascribed to certain attributes, particularly those that favour commercial or political interests, while other attributes that are highly valued by society, particularly those related to care processes, may be omitted or undervalued. This may be compounded by a lack of transparency to relevant stakeholders, resulting in an inability for them to participate in, or challenge, the decisions. The makes it likely that costly new technologies, for which inflated prices can be justified by the current value frameworks, are displacing aspects of healthcare that are highly valued by society.

Potential for epistemic injustice in evidence-based healthcare policy and guidance.

The rapid development in healthcare technologies in recent years has resulted in the need for health services, whether publicly funded or insurance based, to identify means to maximise the benefits and provide equitable distribution of limited resources. This has resulted in the need for rationing decisions, and there has been considerable debate regarding the substantive and procedural ethical principles that promote distributive justice when making such decisions. In this paper, I argue that while the scientifically rigorous approaches of evidence-based healthcare are claimed as aspects of procedural justice that legitimise such guidance, there are biases and distortions in all aspects of the process that may lead to epistemic injustices. Regardless of adherence to principles of distributive justice in the decision-making process, evidential failings may undermine the fairness and legitimacy of such decisions. In particular, I identify epistemic exclusion that denies certain patient and professional groups the opportunity to contribute to the epistemic endeavour. This occurs at all stages of the process, from the generation, analysis and reporting of the underlying evidence, through the interpretation of such evidence, to the decision-making that determines access to healthcare resources. I further argue that this is compounded by processes which confer unwarranted epistemic privilege on experts in relation to explicit or implicit value judgements, which are not within their remit. I suggest a number of areas in which changes to the processes for developing, regulating, reporting and evaluating evidence may improve the legitimacy of such processes.

Neural Dynamics of Variable Grasp-Movement Preparation in the Macaque Frontoparietal Network.

Our voluntary grasping actions lie on a continuum between immediate action and waiting for the right moment, depending on the context. Therefore, studying grasping requires an investigation into how preparation time affects this process. Two macaque monkeys (Macaca mulatta; one male, one female) performed a grasping task with a short instruction followed by an immediate or delayed go cue (0-1300 ms) while we recorded in parallel from neurons in the grasp preparation relevant area F5 that is part of the ventral premotor cortex, and the anterior intraparietal area (AIP). Initial population dynamics followed a fixed trajectory in the neural state space unique to each grip type, reflecting unavoidable movement selection, then diverged depending on the delay, reaching unique states not achieved for immediately cued movements. Population activity in the AIP was less dynamic, whereas F5 activity continued to evolve throughout the delay. Interestingly, neuronal populations from both areas allowed for a readout tracking subjective anticipation of the go cue that predicted single-trial reaction time. However, the prediction of reaction time was better from F5 activity. Intriguingly, activity during movement initiation clustered into two trajectory groups, corresponding to movements that were either "as fast as possible" or withheld movements, demonstrating a widespread state shift in the frontoparietal grasping network when movements must be withheld. Our results reveal how dissociation between immediate and delay-specific preparatory activity, as well as differentiation between cortical areas, is possible through population-level analysis.SIGNIFICANCE STATEMENT Sometimes when we move, we consciously plan our movements. At other times, we move instantly, seemingly with no planning at all. Yet, it's unclear how preparation for movements along this spectrum of planned and seemingly unplanned movement differs in the brain. Two macaque monkeys made reach-to-grasp movements after varying amounts of preparation time while we recorded from the premotor and parietal cortex. We found that the initial response to a grasp instruction was specific to the required movement, but not to the preparation time, reflecting required movement selection. However, when more preparation time was given, neural activity achieved unique states that likely related to withholding movements and anticipation of movement, shedding light on the roles of the premotor and parietal cortex in grasp planning.

Analysis of clinical benefit, harms, and cost-effectiveness of screening women for abdominal aortic aneurysm.

BACKGROUND: A third of deaths in the UK from ruptured abdominal aortic aneurysm (AAA) are in women. In men, national screening programmes reduce deaths from AAA and are cost-effective. The benefits, harms, and cost-effectiveness in offering a similar programme to women have not been formally assessed, and this was the aim of this study. METHODS: We developed a decision model to assess predefined outcomes of death caused by AAA, life years, quality-adjusted life years, costs, and the incremental cost-effectiveness ratio for a population of women invited to AAA screening versus a population who were not invited to screening. A discrete event simulation model was set up for AAA screening, surveillance, and intervention. Relevant women-specific parameters were obtained from sources including systematic literature reviews, national registry or administrative databases, major AAA surgery trials, and UK National Health Service reference costs. FINDINGS: AAA screening for women, as currently offered to UK men (at age 65 years, with an AAA diagnosis at an aortic diameter of ≥3·0 cm, and elective repair considered at ≥5·5cm) gave, over 30 years, an estimated incremental cost-effectiveness ratio of £30 000 (95% CI 12 000-87 000) per quality-adjusted life year gained, with 3900 invitations to screening required to prevent one AAA-related death and an overdiagnosis rate of 33%. A modified option for women (screening at age 70 years, diagnosis at 2·5 cm and repair at 5·0 cm) was estimated to have an incremental cost-effectiveness ratio of £23 000 (9500-71 000) per quality-adjusted life year and 1800 invitations to screening required to prevent one AAA-death, but an overdiagnosis rate of 55%. There was considerable uncertainty in the cost-effectiveness ratio, largely driven by uncertainty about AAA prevalence, the distribution of aortic sizes for women at different ages, and the effect of screening on quality of life. INTERPRETATION: By UK standards, an AAA screening programme for women, designed to be similar to that used to screen men, is unlikely to be cost-effective. Further research on the aortic diameter distribution in women and potential quality of life decrements associated with screening are needed to assess the full benefits and harms of modified options. FUNDING: UK National Institute for Health Research Health Technology Assessment programme.

Outcomes of aortic aneurysm surgery in England: a nationwide cohort study using hospital admissions data from 2002 to 2015.

BACKGROUND: The United Kingdom aortic aneurysms (AA) services have undergone reconfiguration to improve outcomes. The National Health Service collects data on all hospital admissions in England. The complex administrative datasets generated have the potential to be used to monitor activity and outcomes, however, there are challenges in using these data as they are primarily collected for administrative purposes. The aim of this study was to develop standardised algorithms with the support of a clinical consensus group to identify all AA activity, classify the AA management into clinically meaningful case mix groups and define outcome measures that could be used to compare outcomes among AA service providers. METHODS: In-patient data about aortic aneurysm (AA) admissions from the 2002/03 to 2014/15 were acquired. A stepwise approach, with input from a clinical consensus group, was used to identify relevant cases. The data is primarily coded into episodes, these were amalgamated to identify admissions; admissions were linked to understand patient pathways and index admissions. Cases were then divided into case-mix groups based upon examination of individually sampled and aggregate data. Consistent measures of outcome were developed, including length of stay, complications within the index admission, post-operative mortality and re-admission. RESULTS: Several issues were identified in the dataset including potential conflict in identifying emergency and elective cases and potential confusion if an inappropriate admission definition is used. Ninety six thousand seven hundred thirty-five patients were identified using the algorithms developed in this study to extract AA cases from Hospital episode statistics. From 2002 to 2015, 83,968 patients (87% of all cases identified) underwent repair for AA and 12,767 patients (13% of all cases identified) died in hospital without any AA repair. Six thousand three hundred twenty-nine patients (7.5%) had repair for complex AA and 77,639 (92.5%) had repair for infra-renal AA. CONCLUSION: The proposed methods define homogeneous clinical groups and outcomes by combining administrative codes in the data. These methodologically robust methods can help examine outcomes associated with previous and current service provisions and aid future reconfiguration of aortic aneurysm surgery services.

Experiences of living with varicose veins: A systematic review of qualitative research.

AIM: To identify the symptoms and quality of life impacts that are important from the perspective of patients with varicose veins and to compare identified themes to items in varicose vein patient-reported outcome measures (PROMs). BACKGROUND: Varicose veins are common worldwide and are considered a chronic condition with implications for quality of life. Treatment is predominantly conservative; therefore, understanding patients' experiences of living with varicose veins is important to inform the provision of clinical care. PROMs are often used to collect data about patients' quality of life. DESIGN: Thematic synthesis of qualitative research reported according to ENTREQ guidelines. METHODS: Multiple electronic databases, including MEDLINE and CINAHL, were systematically searched to identify qualitative research examining experiences of adults with varicose veins. Thematic synthesis was then conducted on the included studies. RESULTS: Three studies met the inclusion criteria; the quality of the studies was high. The range and intensity of reported symptoms and participant's experiences of living with varicose veins were varied. Five overarching themes were identified: physical, psychological and social impact of varicose veins, adapting to varicose veins and reasons for seeking treatment. The overall key theme to emerge was adaptation, with patients demonstrating how they adapted to the various impacts. CONCLUSION: This review demonstrates that varicose veins have a wide range of symptoms and may have a significant impact on quality of life; people made significant adaptations to enable them to live their lives as fully as possible. RELEVANCE TO CLINICAL PRACTICE: Healthcare professionals need to be aware of the range of symptoms and their impact on quality of life. The use of PROMs to gather information about quality of life and symptoms is well established globally; however, PROMs currently used may not capture the full extent of the impact on patient's quality of life.

Participant experiences in a feasibility trial of supervised exercise training in adults with venous leg ulcers: A qualitative study.

Exercise training can improve lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration; however, there is a lack of research on patients' views about the acceptability and feasibility of exercise interventions. The aim of this study was to explore participants' experiences of the trial "Exploring the Feasibility of Implementing a Supervised Exercise Training and Compression Hosiery Intervention in Patients with Venous Ulceration" (FISCU). Semi-structured face-to-face and telephone interviews were used to investigate participants' experiences (n = 16) of taking part in the FISCU trial. Data were analysed using thematic analysis. Three overarching themes were identified, along with 11 sub-themes: (a) sedentary cautious living (because of pain and reduced mobility, treatment and perceived control, and advice to rest and be careful), (b) key components of the exercise trial (including motivation, an individualised intervention supervised by a specialist exercise professional, and satisfaction with the intervention), and (c) benefits of exercise (physical benefits and healing, psychological well-being, positive impact on comorbidities, and an improved self-management strategy). This study found that an exercise intervention was viewed by participants as positive, acceptable, and feasible while living with a venous leg ulcer. An individualised and supervised exercise programme was key to build confidence to exercise.

Patient-Reported Outcome Measures in Carotid Artery Revascularization: Systematic Review and Psychometric Analysis.

BACKGROUND: Patient-reported outcome measures (PROMs) provide a way to measure the impact of a disease and its associated treatments on the quality of life (QoL) from the patients' perspective. The aim of this review was to identify PROMs that have been developed and/or validated in patients with carotid artery stenosis (CAS) undergoing revascularization and to assess their psychometric properties and examine suitability for research and clinical use. METHODS: Eight electronic databases including MEDLINE and CINAHL were searched using a 2-stage search approach to identify studies reporting the development and/or validation of relevant PROMs in patients with CAS undergoing revascularization. Supplementary citation searching and hand-searching reference lists of included studies were also undertaken. The COnsensus-based Standards for the selection of health Measurement INstruments and Oxford criteria were used to assess the methodological quality of the included studies, and the psychometric properties of the PROMs were evaluated using established assessment criteria. RESULTS: Five studies reporting on 6 PROMs were included: 36-Item Short Form Health Survey (SF-36), Euro-QoL-5-Dimension Scale (EQ-5D), Hospital Anxiety and Depression Scale, Dizziness Handicap Inventory, QoL for carotid artery disease scale, and a disease-specific PROM for CAS. The rigor of the psychometric assessment of the PROMs was variable with most only attempting to assess a single psychometric criterion. No study reported evidence on construct validity and test-retest reliability. Evidence for acceptability for the use of SF-36, EQ-5D, and the disease-specific PROM was rated good in most studies. Only one study reported a Cronbach alpha score >0.70 as evidence of internal consistency. Overall, the psychometric evaluation of all included PROMs was rated as poor within the CAS population undergoing revascularization. CONCLUSIONS: This review highlighted a lack of evidence in validated PROMs used for patients undergoing carotid artery revascularization. As a result, the development and validation of a new PROM for this patient population is warranted to provide data which can supplement traditional clinical outcomes (stroke<30 days post-procedural, myocardial infarction, and death) and capture changes in health status and QoL to help inform treatment decisions.

Effects of supervised exercise training on lower-limb cutaneous microvascular reactivity in adults with venous ulcers.

PURPOSE: To investigate the effects of a 12-week supervised exercise programme on lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration. METHODS: Thirty-eight adults with unilateral venous ulceration who were being treated with lower-limb compression therapy (58% male; mean age 65 years; median ulcer size 5 cm2) were randomly allocated to exercise or control groups. Exercise participants (n = 18) were invited to attend thrice weekly sessions of lower-limb aerobic and resistance exercise for 12 weeks. Cutaneous microvascular reactivity was assessed in the gaiter region of ulcerated and non-ulcerated legs at baseline and 3 months using laser Doppler fluxmetry coupled with iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous vascular conductance (CVC) was calculated as laser Doppler flux (AU)/mean arterial pressure (mmHg). RESULTS: Thirty-seven participants completed follow-up assessments. Median session attendance was 36 (range 2-36). Analyses of covariance revealed greater peak CVC responses to ACh in the exercise group at 3 months in both the ulcerated (adjusted difference = 0.944 AU/mmHg; 95% CI 0.504-1.384) and non-ulcerated (adjusted difference = 0.596 AU/mmHg; 95% CI 0.028-1.164) legs. Peak CVC responses to SNP were also greater in the exercise group at 3 months in the ulcerated leg (adjusted difference = 0.882 AU/mmHg; 95% CI 0.274-1.491), but not the non-ulcerated leg (adjusted difference = 0.392 AU/mmHg; 95% CI - 0.377 to 1.161). CONCLUSION: Supervised exercise training improves lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration.

A systematic review of qualitative research into people's experiences of living with venous leg ulcers.

AIM: To systematically identify, evaluate and synthesize qualitative research that examined the symptoms and health-related quality of life themes that are important from the perspective of patients with venous leg ulceration. BACKGROUND: Venous leg ulceration is a common chronic condition; the symptoms and associated treatments have a negative effect on health-related quality of life. Qualitative research methods can provide insight into the personal experiences of patients with venous leg ulceration. DESIGN: Qualitative evidence synthesis (using framework synthesis). DATA SOURCES: Multiple electronic databases including MEDLINE, EMBASE, PsycINFO and CINAHL were comprehensively searched from inception to November 2015. REVIEW METHODS: Systematic identification, quality assessment and synthesis of existing qualitative research were performed; framework synthesis was conducted on included studies. An inductive approach was used and emergent themes were identified. The final stage in the synthesis involved the development of new interpretations. RESULTS: Thirteen studies met the inclusion criteria; the overall quality of the included studies was good. Four overarching themes were identified; physical impact, psychological impact, social impact and treatment and, in these, further subthemes were identified. Ulcer and treatment-related pain, as well as odour and exudate appeared to have significant and direct negative effects on quality of life, with additional and cumulative effects on sleep, mobility and mood. CONCLUSION: The themes identified in this review should be considered by professionals providing services, care and treatment for venous leg ulcer patients and in the selection, or development, of patient-reported outcome measures for use with this population.

Exercise fidelity and progression in a supervised exercise programme for adults with venous leg ulcers.

Despite exercise being included in the recommended advice for patients with venous leg ulcers, there is a fear shared by clinicians and patients that exercise may be either inappropriate or harmful and actually delay rather than promote healing. Therefore, before implementing a larger-scale study exploring the effects of a supervised exercise programme in patients with venous ulcers being treated with compression therapy, it is important to assess exercise safety as well as fidelity and progression in a feasibility study. Eighteen participants randomised in the exercise group were asked to undertake 36 (3 times/week for 12 weeks) 60-min exercise sessions, each comprising moderate-intensity aerobic, resistance, and flexibility exercise components. For the purposes of this paper, we analysed the data collected during the exercise sessions. The overall session attendance rate was 79%, with 13 of 18 participants completing all sessions. No in-session adverse events were reported; 100% aerobic components and 91% of resistance components were completed within the desired moderate-intensity target. Similarly, 81% of aerobic components and 93% of flexibility components were completed within the prescribed duration targets. Our data showed that patients with venous ulcers could safely follow a supervised exercise programme incorporating moderate-intensity aerobic, resistance, and flexibility components.

Neural Population Dynamics during Reaching Are Better Explained by a Dynamical System than Representational Tuning.

Recent models of movement generation in motor cortex have sought to explain neural activity not as a function of movement parameters, known as representational models, but as a dynamical system acting at the level of the population. Despite evidence supporting this framework, the evaluation of representational models and their integration with dynamical systems is incomplete in the literature. Using a representational velocity-tuning based simulation of center-out reaching, we show that incorporating variable latency offsets between neural activity and kinematics is sufficient to generate rotational dynamics at the level of neural populations, a phenomenon observed in motor cortex. However, we developed a covariance-matched permutation test (CMPT) that reassigns neural data between task conditions independently for each neuron while maintaining overall neuron-to-neuron relationships, revealing that rotations based on the representational model did not uniquely depend on the underlying condition structure. In contrast, rotations based on either a dynamical model or motor cortex data depend on this relationship, providing evidence that the dynamical model more readily explains motor cortex activity. Importantly, implementing a recurrent neural network we demonstrate that both representational tuning properties and rotational dynamics emerge, providing evidence that a dynamical system can reproduce previous findings of representational tuning. Finally, using motor cortex data in combination with the CMPT, we show that results based on small numbers of neurons or conditions should be interpreted cautiously, potentially informing future experimental design. Together, our findings reinforce the view that representational models lack the explanatory power to describe complex aspects of single neuron and population level activity.

The Relationship between Hospital or Surgeon Volume and Outcomes in Lower Limb Vascular Surgery in the United Kingdom and Europe.

BACKGROUND: Peripheral vascular disease is a major cause of death and disability. The extent to which volume influences outcome of lower limb (LL) vascular surgery remains unclear. This review evaluated the relationship between hospital/surgeon volume and outcome in LL surgery. METHODS: Electronic databases-MEDLINE, Embase, the Cochrane Library Databases, Science Citation Index, and CINAHL-proceedings from conferences, citations, and references of included studies were searched. Studies from Europe, of adults undergoing LL vascular surgery reporting outcomes by hospital or surgeon volume were included. The quality of studies was assessed using a modified Cochrane Risk Of Bias Assessment Tool: for Non-Randomized Studies of Interventions (Robins1) tool. The association between hospital/surgeon volume and outcome was summarized using tables. RESULTS: Nine studies from different European countries, comprising 67,445 patients who had undergone diverse LL surgeries were included. The increase in hospital/surgeon volume was associated with a decrease in post-operative amputations (hospital at 30 days [odds ratio {OR}: 0.20, 95% confidence interval {CI} 0.29-0.45, P = 0.01; OR: 0.67, 95% CI 0.44-0.9, P = 0.05; OR: 0.96, 95% CI 0.92-1.00, P = 0.06], at 1 year [OR: 0.96, 95% CI 0.93-0.98, P = 0.002; OR: 0.66, 95% CI 0.52-0.84, P < 0.001; OR: 2.05, 95% CI 1.24-3.42, P = 0.01], surgeon at 30 days [OR: 0.53, 95% CI 0.36-0.87, P = 0.01; OR: 0.40, 95% CI 0.18-0.91, P = 0.03; OR: 0.41, 95% CI 0.24-0.69, P = 0.0006]). The evidence on an association between hospital/surgeon volume and mortality was contradictory, but mortality and amputations may covary by hospital volume. There were an insufficient number of studies reporting on the other variables to draw firm conclusions, but their results suggest that high-volume hospitals may undertake more repeated surgeries/revascularizations and limb salvage. The impact of hospital/surgical volume on adverse events and length of hospitalization could not be determined. CONCLUSIONS: High-volume hospitals/surgeons may undertake fewer amputations and mortality and amputations may covary. The finding that hospital and surgeon volume affected the number of secondary amputations has implications on reorganization of vascular surgery services. However, due to the small number and poor quality of some of the included studies, decisions on reorganization of LL vascular surgery services should be supplemented by results from clinical audits. There is need for standardization of definition of volume stratification of outcomes by patient's clinical conditions.

Predicting Reaction Time from the Neural State Space of the Premotor and Parietal Grasping Network.

Neural networks of the brain involved in the planning and execution of grasping movements are not fully understood. The network formed by macaque anterior intraparietal area (AIP) and hand area (F5) of the ventral premotor cortex is implicated strongly in the generation of grasping movements. However, the differential role of each area in this frontoparietal network is unclear. We recorded spiking activity from many electrodes in parallel in AIP and F5 while three macaque monkeys (Macaca mulatta) performed a delayed grasping task. By analyzing neural population activity during action preparation, we found that state space analysis of simultaneously recorded units is significantly more predictive of subsequent reaction times (RTs) than traditional methods. Furthermore, because we observed a wide variety of individual unit characteristics, we developed the sign-corrected average rate (SCAR) method of neural population averaging. The SCAR method was able to explain at least as much variance in RT overall as state space methods. Overall, F5 activity predicted RT (18% variance explained) significantly better than AIP (6%). The SCAR methods provides a straightforward interpretation of population activity, although other state space methods could provide richer descriptions of population dynamics. Together, these results lend support to the differential role of the parietal and frontal cortices in preparation for grasping, suggesting that variability in preparatory activity in F5 has a more potent effect on trial-to-trial RT variability than AIP. SIGNIFICANCE STATEMENT: Grasping movements are planned before they are executed, but how is the preparatory activity in a population of neurons related to the subsequent reaction time (RT)? A population analysis of the activity of many neurons recorded in parallel in macaque premotor (F5) and parietal (AIP) cortices during a delayed grasping task revealed that preparatory activity in F5 could explain a threefold larger fraction of variability in trial-to-trial RT than AIP. These striking differences lend additional support to a differential role of the parietal and premotor cortices in grasp movement preparation, suggesting that F5 has a more direct influence on trial-to-trial variability and movement timing, whereas AIP might be more closely linked to overall movement intentions.

Patient-reported outcome measures in patients with peripheral arterial disease: a systematic review of psychometric properties.

BACKGROUND: Peripheral arterial disease (PAD) is generally associated with considerable morbidity and reduced quality of life. Patient-reported outcome measures (PROMs) provide important information about the burden of disease and impact of treatment in affected patients. OBJECTIVES: The objective of the review was to identify and appraise studies reporting the psychometric evaluation of PROMs administered to a specified population of patients with PAD with a view to recommending suitable PROMs. METHODS: A systematic review of peer-reviewed English language articles was undertaken to identify primary studies reporting psychometric properties of PROMs in English-speaking patients with various stages of PAD. Comprehensive searches were completed up until January 2015. Study selection, data extraction and quality assessment were undertaken independently by at least two researchers. Findings were presented as tabular and narrative summaries based on accepted guidance. RESULTS: Psychometric evaluation of 6 generic and 7 condition-specific PROMs reported in 14 studies contributed data to the review. The frequently reported measure was the SF-36 (n = 11 studies); others included the Walking Impairment Questionnaire (n = 8 studies), EQ-5D (n = 5 studies) and the Vascular Quality of Life Questionnaire (n = 3 studies). Studies included a diverse PAD population and varied in methodology, including approach to validation of PROMs. CONCLUSIONS: Various PROMs have been validated in patients with PAD but no study provided evidence of a full psychometric evaluation in the patient population. Careful selection is required to identify reliable and valid PROMs to use in clinical and research settings.

The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.

UNLABELLED: The aim of this study was to develop and pilot a group education programme for promoting walking in people with intermittent claudication. Patient focus groups (n=24) and literature reviews were conducted to inform the development of the education programme, which involves a three-hour group-based education workshop and follow-up telephone support. A pilot study was subsequently conducted in which 23 new patients (Rutherford category 1-3) were randomly assigned to usual care (control) or usual care plus the education programme. Outcomes were assessed at baseline and six weeks including daily steps (tri-axial accelerometer), walking capacity (six-minute walk test and Gardner treadmill test), and quality of life (Intermittent Claudication Questionnaire [ICQ]). Exit interviews were conducted to assess the acceptability and usefulness of the programme. Compared with controls, the intervention group had superior walking capacity and quality of life at six weeks. Mean differences in six-minute walk distance, treadmill maximum walking distance and ICQ score were 44.9 m (95% confidence interval [CI], 6.9 to 82.9), 173 m (95% CI, 23 to 322), and -10.6 (95% CI, -18.9 to -2.3), respectively. The daily step count did not differ between groups. The exit interviews indicated that participants valued attending the programme, that it gave them a greater understanding of their condition, and that they had been walking more for exercise since attending. The results suggest that the education programme is feasible, acceptable, and potentially useful for improving walking capacity and quality of life. A fully-powered trial exploring clinical and cost effectiveness is needed. TRIAL REGISTRATION NUMBER: ISRCTN06733130 (http://www.controlled-trials.com).

Pentoxifylline for intermittent claudication.

BACKGROUND: Intermittent claudication (IC) is a symptom of peripheral arterial disease (PAD) and is associated with high morbidity and mortality. Pentoxifylline, one of many drugs used to treat IC, acts by decreasing blood viscosity, improving erythrocyte flexibility and promoting microcirculatory flow and tissue oxygen concentration. Many studies have evaluated the efficacy of pentoxifylline in treating individuals with PAD, but results of these studies are variable. This is an update of a review first published in 2012. OBJECTIVES: To determine the efficacy of pentoxifylline in improving the walking capacity (i.e. pain-free walking distance and total (absolute, maximum) walking distance) of individuals with stable intermittent claudication, Fontaine stage II. SEARCH METHODS: For this update, the Cochrane Vascular Group Trials Search Co-ordinator searched the Specialised Register (last searched April 2015) and the Cochrane Register of Studies (2015, Issue 3). SELECTION CRITERIA: All double-blind, randomised controlled trials (RCTs) comparing pentoxifylline versus placebo or any other pharmacological intervention in patients with IC Fontaine stage II. DATA COLLECTION AND ANALYSIS: Two review authors separately assessed included studies,. matched data and resolved disagreements by discussion. Review authors assessed the methodological quality of studies by using the Cochrane 'Risk of bias' tool and collected results related to pain-free walking distance (PFWD) and total walking distance (TWD). Comparison of studies was based on duration and dose of pentoxifylline. MAIN RESULTS: We included in this review 24 studies with 3377 participants. Seventeen studies compared pentoxifylline versus placebo. In the seven remaining studies, pentoxifylline was compared with flunarizine (one study), aspirin (one study), Gingko biloba extract (one study), nylidrin hydrochloride (one study), prostaglandin E1 (two studies) and buflomedil and nifedipine (one study). The quality of the evidence was generally low, with large variability in reported findings.. Most included studies did not report on random sequence generation and allocation concealment, did not provide adequate information to allow selective reporting to be judged and did not report blinding of assessors. Heterogeneity between included studies was considerable with regards to multiple variables, including duration of treatment, dose of pentoxifylline, baseline walking distance and participant characteristics; therefore, pooled analysis was not possible.Of 17 studies comparing pentoxifylline with placebo, 14 reported TWD and 11 reported PFWD; the difference in percentage improvement in TWD for pentoxifylline over placebo ranged from 1.2% to 155.9%, and in PFWD from -33.8% to 73.9%. Testing the statistical significance of these results generally was not possible because data were insufficient. Most included studies suggested improvement in PFWD and TWD for pentoxifylline over placebo and other treatments, but the statistical and clinical significance of findings from individual trials is unclear. Pentoxifylline generally was well tolerated; the most commonly reported side effects consisted of gastrointestinal symptoms such as nausea. AUTHORS' CONCLUSIONS: Given the generally poor quality of published studies and the large degree of heterogeneity evident in interventions and in results, the overall benefit of pentoxifylline for patients with Fontaine class II intermittent claudication remains uncertain. Pentoxifylline was shown to be generally well tolerated.Based on total available evidence, high-quality data are currently insufficient to reveal the benefits of pentoxifylline for intermittent claudication.