DCDavid Leslie Cohen

David Leslie Cohen

*This is an algorithmically generated author record based on publicly available information.

David Leslie Cohen has a total of 1000 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Impact of COVID-19 on Stroke Caseload in a Major Hyperacute Stroke Unit

    by Fionn Mag Uidhir, Raj Bathula, Aravinth Sivagnanaratnam, Mudhar Abdul-Saheb, Joseph Devine, David L. Cohen


  • Robot-assisted training compared with an enhanced upper limb therapy programme and with usual care for upper limb functional limitation after stroke: the RATULS three-group RCT

    by Helen Rodgers, Helen Bosomworth, Hermano I Krebs, Frederike van Wijck, Denise Howel, Nina Wilson, Tracy Finch, Natasha Alvarado, Laura Ternent, Cristina Fernandez-Garcia, et al.

    Background: Loss of arm function is common after stroke. Robot-assisted training may improve arm outcomes.Objective: The objectives were to determine the clinical effectiveness and cost-effectiveness of robot-assisted training, compared with an enhanced upper limb therapy programme and with usual care.Design: This was a pragmatic, observer-blind, multicentre randomised controlled trial with embedded health economic and process evaluations.Setting: The trial was set in four NHS trial centres.Participants: Patients with moderate or severe upper limb functional limitation, between 1 week and 5 years following first stroke, were recruited.Interventions: Robot-assisted training using the Massachusetts Institute of Technology-Manus robotic gym system (InMotion commercial version, Interactive Motion Technologies, Inc., Watertown, MA, USA), an enhanced upper limb therapy programme comprising repetitive functional task practice, and usual care.Main outcome measures: The primary outcome was upper limb functional recovery ‘success’ (assessed using the Action Research Arm Test) at 3 months. Secondary outcomes at 3 and 6 months were the Action Research Arm Test results, upper limb impairment (measured using the Fugl-Meyer Assessment), activities of daily living (measured using the Barthel Activities of Daily Living Index), quality of life (measured using the Stroke Impact Scale), resource use costs and quality-adjusted life-years.Results: A total of 770 participants were randomised (robot-assisted training,n = 257; enhanced upper limb therapy,n = 259; usual care,n = 254). Upper limb functional recovery ‘success’ was achieved in the robot-assisted training [103/232 (44%)], enhanced upper limb therapy [118/234 (50%)] and usual care groups [85/203 (42%)]. These differences were not statistically significant; the adjusted odds ratios were as follows: robot-assisted training versus usual care, 1.2 (98.33% confidence interval 0.7 to 2.0); enhanced upper limb therapy versus usual care, 1.5 (98.33% confidence interval 0.9 to 2.5); and robot-assisted training versus enhanced upper limb therapy, 0.8 (98.33% confidence interval 0.5 to 1.3). The robot-assisted training group had less upper limb impairment (as measured by the Fugl-Meyer Assessment motor subscale) than the usual care group at 3 and 6 months. The enhanced upper limb therapy group had less upper limb impairment (as measured by the Fugl-Meyer Assessment motor subscale), better mobility (as measured by the Stroke Impact Scale mobility domain) and better performance in activities of daily living (as measured by the Stroke Impact Scale activities of daily living domain) than the usual care group, at 3 months. The robot-assisted training group performed less well in activities of daily living (as measured by the Stroke Impact Scale activities of daily living domain) than the enhanced upper limb therapy group at 3 months. No other differences were clinically important and statistically significant. Participants found the robot-assisted training and the enhanced upper limb therapy group programmes acceptable. Neither intervention, as provided in this trial, was cost-effective at current National Institute for Health and Care Excellence willingness-to-pay thresholds for a quality-adjusted life-year.Conclusions: Robot-assisted training did not improve upper limb function compared with usual care. Although robot-assisted training improved upper limb impairment, this did not translate into improvements in other outcomes. Enhanced upper limb therapy resulted in potentially important improvements on upper limb impairment, in performance of activities of daily living, and in mobility. Neither intervention was cost-effective.Future work: Further research is needed to find ways to translate the improvements in upper limb impairment seen with robot-assisted training into improvements in upper limb function and activities of daily living. Innovations to make rehabilitation programmes more cost-effective are required.Limitations: Pragmatic inclusion criteria led to the recruitment of some participants with little prospect of recovery. The attrition rate was higher in the usual care group than in the robot-assisted training or enhanced upper limb therapy groups, and differential attrition is a potential source of bias. Obtaining accurate information about the usual care that participants were receiving was a challenge.Trial registration: Current Controlled Trials ISRCTN69371850.Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 24, No. 54. See the NIHR Journals Library website for further project information.


  • Open Access

    Risk factors for severe disease in patients admitted with COVID-19 to a hospital in London, England: a retrospective cohort study

    by Jack W Goodall, Thomas A N Reed, Maddalena Ardissino, Paul Bassett, Ashley M Whittington, David L Cohen, Nidhi Vaid

    Summary: COVID-19 has caused a major global pandemic and necessitated unprecedented public health restrictions in almost every country. Understanding risk factors for severe disease in hospitalized patients is critical as the pandemic progresses. This observational cohort study aimed to characterize the independent associations between the clinical outcomes of hospitalized patients and their demographics, comorbidities, blood tests and bedside observations. All patients admitted to Northwick Park Hospital, London, United Kingdom between 12 March and 15 April 2020 with COVID-19 were retrospectively identified. The primary outcome was death. Associations were explored using Cox proportional hazards modelling. The study included 981 patients. The mortality rate was 36.0%. Age (adjusted hazard ratio (aHR) 1.53), respiratory disease (aHR 1.37), immunosuppression (aHR 2.23), respiratory rate (aHR 1.28), hypoxia (aHR 1.36), Glasgow Coma Score <15 (aHR 1.92), urea (aHR 2.67), alkaline phosphatase (aHR 2.53), C-reactive protein (aHR 1.15), lactate (aHR 2.67), platelet count (aHR 0.77) and infiltrates on chest radiograph (aHR 1.89) were all associated with mortality. These important data will aid clinical risk stratification and provide direction for further research.


  • Open Access

    Evaluation of the enhanced upper limb therapy programme within the Robot-Assisted Training for the Upper Limb after Stroke trial: descriptive analysis of intervention fidelity, goal selection and goal achievement

    by Helen Bosomworth, Helen Rodgers, Lisa Shaw, Leanne Smith, Lydia Aird, Denise Howel, Nina Wilson, Natasha Alvarado, Sreeman Andole, David L Cohen, et al.

    Objective: To report the fidelity of the enhanced upper limb therapy programme within the Robot-Assisted Training for the Upper Limb after stroke (RATULS) randomized controlled trial, the types of goals selected and the proportion of goals achieved. Design: Descriptive analysis of data on fidelity, goal selection and achievement from an intervention group within a randomized controlled trial. Setting: Out-patient stroke rehabilitation within four UK NHS centres. Subjects: 259 participants with moderate-severe upper limb activity limitation (Action Research Arm Test 0–39) between one week and five years post first stroke. Intervention: The enhanced upper limb therapy programme aimed to provide 36 one-hour sessions, including 45 minutes of face-to-face therapy focusing on personal goals, over 12 weeks. Results: 7877/9324 (84%) sessions were attended; a median of 34 [IQR 29–36] per participant. A median of 127 [IQR 70–190] repetitions were achieved per participant per session attended. Based upon the Canadian Occupational Performance Measure, goal categories were: self-care 1449/2664 (54%); productivity 374/2664 (14%); leisure 180/2664 (7%) and ‘other’ 661/2664 (25%). For the 2051/2664 goals for which data were available, 1287 (51%) were achieved, ranging between 27% by participants more than 12 months post stroke with baseline Action Research Arm Test scores 0–7, and 88% by those less than three months after stroke with scores 8–19. Conclusions: Intervention fidelity was high. Goals relating to self-care were most commonly selected. The proportion of goals achieved varied, depending on time post stroke and baseline arm activity limitation.


  • Temporal variations in quality of acute stroke care and outcomes in London hyperacute stroke units: a mixed-methods study

    by Robert Simister, Georgia B Black, Mariya Melnychuk, Angus Ig Ramsay, Abigail Baim-Lance, David L Cohen, Jeannie Eng, Penny D Xanthopoulou, Martin M Brown, Anthony G Rudd, et al.

    Background: Seven-day working in hospitals is a current priority of international health research and policy. Previous research has shown variability in delivering evidence-based clinical interventions across different times of the day and week. We aimed to identify factors influencing such variations in London hyperacute stroke units. Objectives: To investigate variations in quality of acute stroke care and outcomes by day and time of admission in London hyperacute stroke units, and to identify factors influencing such variations. Design: This was a prospective cohort study using anonymised patient-level data from the Sentinel Stroke National Audit Programme. Factors influencing variations in care and outcomes were studied through interview and observation data. Setting: The setting was acute stroke services in London hyperacute stroke units. Participants: A total of 7094 patients with a primary diagnosis of stroke took part. We interviewed hyperacute stroke unit staff (n = 76), including doctors, nurses, therapists and administrators, and 31 patients and carers. We also conducted non-participant observations of delivery of care at different times of the day and week (n = 45, ≈102 hours). Intervention: Hub-and-spoke model for care of suspected acute stroke patients in London with performance standards was designed to deliver uniform access to high-quality hyperacute stroke unit care across the week. Main outcome measures: Indicators of quality of acute stroke care, mortality at 3 days after admission, disability at the end of the inpatient spell and length of stay. Data sources: Sentinel Stroke National Audit Programme data for all patients in London hyperacute stroke units with a primary diagnosis of stroke between 1 January and 31 December 2014, and nurse staffing data for all eight London hyperacute stroke units for the same period. Results: We found no variation in quality of care by day and time of admission across the week in terms of stroke nursing assessment, brain scanning and thrombolysis in London hyperacute stroke units, nor in 3-day mortality nor disability at hospital discharge. Other quality-of-care measures significantly varied by day and time of admission. Quality of care was better if the nurse in charge was at a higher band and/or there were more nurses on duty. Staff deliver ‘front-door’ interventions consistently by taking on additional responsibilities out of hours, creating continuities between day and night, building trusting relationships and prioritising ‘front-door’ interventions. Limitations: We were unable to measure long-term outcomes as our request to the Sentinel Stroke National Audit Programme, the Healthcare Quality Improvement Partnership and NHS Digital for Sentinel Stroke National Audit Programme data linked with patient mortality status was not fulfilled. Conclusions: Organisational factors influence 24 hours a day, 7 days a week (24/7), provision of stroke care, creating temporal patterns of provision reflected in patient outcomes, including mortality, length of stay and functional independence. Future work: Further research would help to explore 24/7 stroke systems in other contexts. We need a clearer understanding of variations by looking at absolute time intervals, rather than achievement of targets. Research is needed with longer-term mortality and modified Rankin Scale data, and a more meaningful range of outcomes. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 34. See the NIHR Journals Library website for further project information.


  • Open Access

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

    by Rustam Al-Shahi Salman, David P Minks, Dipayan Mitra, Mark A Rodrigues, Priya Bhatnagar, Johann C du Plessis, Yogish Joshi, Martin S Dennis, Gordon D Murray, David E Newby, et al.


  • Top Cited Papers
    Open Access

    Robot assisted training for the upper limb after stroke (RATULS): a multicentre randomised controlled trial

    by Helen Rodgers, Helen Bosomworth, Hermano I Krebs, Frederike van Wijck, Denise Howel, Nina Wilson, Lydia Aird, Natasha Alvarado, Sreeman Andole, David L Cohen, et al.


  • Top Cited Papers
    Open Access

    Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

    by Rustam Al-Shahi Salman, Dennis, Pag Sandercock, Clm Sudlow, Jm Wardlaw, Wn Whiteley, Gd Murray, J Stephen, DE Newby, N Sprigg, et al.


  • Open Access

    Masthead

    by Steven Echard, David Cohen, New York, Rohit Loomba, San Diego, Lewis R. Roberts, Hugo R. Rosen, Los Angeles, Jayant A. Talwalkar, Gianfranco Alpini, et al.