Health and Community Sciences

ABLE-BP

Arm based on leg blood pressures - an individual participant data meta-analysis from the INTERPRESS-IPD Collaboration

Hypertension (high blood pressure) is diagnosed and managed using blood pressures measured on the upper arm. However, this is often impractical due to injury, disability, post-surgery or even presence of vascular access devices. Leg blood pressure measurements can be used as an alternative to arm measurement, but limited data exist to guide clinicians’ interpretation of leg blood pressure values for the diagnosis and treatment of hypertension.

Using data from over 33,000 individuals who had blood pressure measured in both their arms and legs, from 14 international studies within the INTERPRESS-IPD Collaboration, we sought to answer the following questions using individual participant data meta-analysis:

  • What is the mean difference, in the absence of peripheral arterial disease, between systolic blood pressure measured in the arm and systolic blood pressure measured in the leg in the same individuals?
  • To what extent do these differences vary according to patient characteristics and methods of measurement, and what are the impacts of cerebrovascular and cardiac diseases on the difference between arm and leg pressures?
  • Can a model be developed and valIdated to predict arm systolic blood pressure, based on leg systolic blood pressure measurements and other patient characteristics, to inform interpretation of individual leg systolic blood pressure readings?
  • How does leg systolic blood pressure, in comparison with models based on arm systolic blood pressure, predict cardiovascular events and/or mortality?

Core Academic Staff

  • Dr Chris Clark NIHR Clinical Lecturer in General Practice and Primary Care, UEMS – Principal Investigator
  • Dr Sinead McDonagh NIHR SPCR Postdoctoral Research Fellow, UEMS – Research Lead and co-applicant
  • Dr James Sheppard Associate Professor, Wellcome Trust/Royal Society Sir Henry Dale Fellow, NIHR Oxford BRC Senior Fellow, University of Oxford – Co-applicant
  • Dr Fiona Warren Senior Lecturer in Medical Statistics, UEMS – Co-applicant
  • Kate Boddy Research Fellow in Patient and Public Involvement, UEMS – Co-applicant
  • Philip Lewis Senior Consultant Cardiologist and Physician - Collaborator
  • Prof Una Martin, Professor of Clinical Pharmacology, University of Birmingham – Co-applicant
  • Jayne Fordham, Practice Nurse, Mid Devon Medical Practice, Witheridge - Collaborator
  • Prof Victor Aboyans Head of Dept. Of Cardiology, Dupuytren University Hospital, Limoges, France – collaborator
  • Chloe Thomas Research Administrator, UEMS

For further information, please contact the Dr Sinead McDonagh at s.t.j.mcdonagh@exeter.ac.uk

Public and Patient Involvement

We have established a patient and public involvement (PPI) advisory group for the ABLE-BP project, led by Kate Boddy (an academic PPI facilitator), and comprising one stroke survivor, Leon Farmer, and two Thalidomide Trust beneficiaries, Helen Shore and Phil Williams; they have shaped the research by fully participating in quarterly management meetings. The group have contributed toward drafting the funding applications, study protocol and the plain English abstract - this helped ensure that the language used was clear and concise for patients and health professionals who may be interested in learning more about the relationship between arm and leg blood pressures and cardiovascular risk assessment. We are in the process of coproducing a dissemination plan to support our forthcoming peer-reviewed publication.

  • McDonagh STJ, Sheppard JP, Warren FC, et al. INTERPRESS-IPD Collaborators. Arm Based on LEg blood pressures (ABLE-BP): can systolic leg blood pressure measurements predict systolic brachial blood pressure? Protocol for an individual participant data meta-analysis from the INTERPRESS-IPD Collaboration. (2021). BMJ Open, 11(3):e040481. https://doi: 10.1136/bmjopen-2020-040481. 
  • Sheppard JP, Albasri A, Franssen M, Fletcher B, Pealing L, Roberts N, Obeid A, Pucci M, McManus RJ, Martin U; British and Irish Hypertension Society. Defining the relationship between arm and leg blood pressure readings: a systematic review and meta-analysis. (2019). Journal of Hypertension. 37(4),660-670. https://doi: 10.1097/HJH.0000000000001958.

Establishment of the INTERPRESS-IPD Collaboration and primary analyses were funded via the NIHR Research for Patient Benefit programme (PB-PG-0215-36009).

The ABLE-BP project was predominantly funded by the Stroke Association (SA PG 19/100043) and also by the Thalidomide Trust (to support patient and public involvement of Thalidomide Trust beneficiaries).

The study is registered with PROSPERO: registration number CRD42015031227.

Analyses are underway and key findings will be reported soon.

These results will provide the first evidence-based method for describing the relationship between arm and leg systolic blood pressure and estimating individual brachial systolic blood pressure and cardiovascular risk, from leg blood pressure measurements, using an individual participant data method. We will create an online calculator to support the prediction of arm blood pressure when only leg blood pressures and patient demographics are available.

Our findings will help clinicians and patients in detecting and managing hypertension more effectively, where leg measurements are required.