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Health and Community Sciences

INTERPRESS-IPD: The Inter-arm blood pressure difference Individual Patient Data Collaboration

Differences in blood pressure between arms (inter-arm difference; IAD) have been associated with increased cardiovascular and all-cause mortality in varied cohort studies. There are limitations to study level meta-analyses of these findings. This project uniquely brings together international data on individuals with blood pressure measured in both arms to address key questions which study-level analyses cannot answer, by using individual patient data meta-analyses.

  • What is the independent contribution of IAD to prognostic risk estimation for cardiovascular and all-cause mortality, and cardiovascular events?
  • What minimum cut-off value for IAD defines elevated risk?
  • What is the incremental association between IAD and mortality risk?

The Collaboration has pooled data for analysis from 24 international cohorts across Europe, North America, Africa and Southeast Asia. We currently hold data on over 57,000 participants. We are addressing these questions by forming an international collaboration, the ‘INTERPRESS-IPD’, to combine individual patient data (IPD) from IAD cohort studies into a single large dataset for IPD meta-analysis.

Primary findings were published online in 2020 in Hypertension.

Core Academic Staff

  • Dr Chris Clark NIHR Clinical Lecturer in General Practice and Primary Care, UEMS – Principal Investigator

  • Prof John Campbell Professor of General Practice and Primary Care, UEMS – Principal Investigator
  • Dr Sinead McDonagh NIHR SPCR Postdoctoral Research Fellow
  • Dr Sarah Moore NIHR SPCR GP Career Progression Fellow
  • Kate Boddy Research Fellow, UEMS – Co-applicant
  • Dr Fiona Warren Senior Lecturer in Medical Statistics, UEMS – Co-applicant
  • Prof Rod Taylor Professor of Population Health Research, University of Glasgow – Co-applicant
  • Tim Eames Medical Research Data Programmer, UEMS
  • Prof Victor Aboyans Head of Dept. Of Cardiology, Dupuytren University Hospital, Limoges, France – Co-applicant
  • Prof Lyne Cloutier Professor in Nursing at Université du Québec à Trois-Rivières, Canada – Co-applicant
  • Prof Richard McManus Professor of Primary Care, University of Oxford – Co-applicant
  • Prof Angela Shore Vice-Dean Research, UEMS – Co-applicant
  • Chloe Thomas Research Administrator, UEMS

For further information, please contact the Research Administrator at

Public & Patient Involvement (PPI)

Our PPI advisory group for the INTERPRESS-IPD project comprised of Malcolm Turner, Nigel Reed, and John Goddard. See more about PPI in INTERPRESS-IPD by following the link to the right of this page.

See our SAPC 2019 contribution here, our INTERPRESS-IPD Poster Presentation, and watch our NIHR New Media Competition 2016 entry.


  • Clark CEBoddy KWarren FC, et al. Associations between interarm differences in blood pressure and cardiovascular disease outcomes: protocol for an individual patient data meta-analysis and development of a prognostic algorithm. 
  • 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. BMJ Open. 2021 Mar 19;11(3):e040481. doi: 10.1136/bmjopen-2020-040481

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

Continuing work on development and secondary research questions is supported by a NIHR School for Primary Care Research Grant (Ref: 512).

The study is registered with PROSPERO: registration number CRD42015031227.

We thank the following colleagues for contributing data to the Collaboration:

Maria Teresa Alzamora

Unitat de Suport a la Recerca Metropolitana Nord, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Mataró, Spain

Rafel Ramos Blanes

Unitat de Suport a la Recerca Girona. Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Institut d’Investigació Biomèdica de Girona (IdIBGi), Department of Medical Sciences, School of Medicine, University of Girona, Girona, Spain

Shao-Yuan Chuang PhD

Institute of Population Health Sciences, National Health Research Institutes (NHRI), No35. Keyan Road, Zhunan, Miaoli County 35053, Taiwan, R.O.C

Michael H Criqui

Department of Family Medicine and Public Health, University of California, San Diego, School of Medicine, 9500 Gilman Drive, La Jolla, CA, 92093-0628, USA

Marie Dahl

Vascular Research Unit, Department of Vascular Surgery, Viborg Regional Hospital, Heibergs Allé 4, 8800 Viborg, Denmark and Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, 8200 Aarhus N, Denmark

Gunnar Engström

Department of Clinical Science in Malmö, Lund University, CRC 60:13, Box 50332, 20213 Malmö, Sweden

Raimund Erbel

Institute of Medical Informatics, Biometry and Epidemiology, University Hospital Essen, Hufelandstraße 55, D-45147 Essen, Germany

Mark Espeland

Division of Gerontology and Geriatric Medicine, Wake Forest School of Medicine, North Carolina, USA

Luigi Ferrucci

National Institute on Aging, 251 Bayview Boulevard, Baltimore MD 21224

Maëlenn Guerchet

INSERM U1094 & IRD, Tropical Neuroepidemiology, Institut d'Epidémiologie et de Neurologie Tropicale (IENT), Faculté de Médecine de l'Université de Limoges - 2 rue du Dr Marcland - 87 025 Limoges Cedex, France

Andrew Hattersley

Institute of Biomedical and Clinical Science, University of Exeter Medical School, College of Medicine and Health, RILD, Barrack Road, Exeter, Devon, England, EX2 5DW

Carlos Lahoz

Lípid and Vascular Risk Unit. Internal Medicine Service. Carlos III - La Paz Hospital. Madrid. Spain.

Robyn L McClelland

Department of Biostatistics, University of Washington, Washington, USA

Mary M McDermott

Northwestern University Feinberg School of Medicine, 750 North Lake Shore Drive, 10th floor, Chicago, IL  b60611, USA

Jackie Price

Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Scotland, EH8 9AG

Henri E Stoffers

Department of Family Medicine, CAPHRI Care and Public Health Research Institute, Maastricht University, P.O.Box 616, 6200 MD Maastricht, The Netherlands

Ji-Guang Wang

Centre for Epidemiological Studies and Clinical Trials, Shanghai Key Laboratory of Hypertension, The Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Ruijin 2nd Road 197, Shanghai 200025, China

Jan Westerink

Department of Vascular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands

James White

DECIPHer, Centre for Trials Research, College of Biomedical and Life Sciences, Cardiff University, 4th Floor, Heath Park, Cardiff, CF14 4YS

Further research questions being addressed by the INTERPRESS-IPD Collaboration include:

  • Which arm should be used to measure blood pressure?
  • Impact of inter-arm blood pressure difference on cardiovascular risk estimation in primary care
  • The association of inter-arm difference and cognitive decline
  • The aetiology of an inter-arm difference in blood pressure

Additional questions to be addressed will be added here as the project evolves.

Find out more about INTERPRESS-IPD and PPI on the APEx web pages.

Risk adjustment tables

The tables below illustrate how cardiovacular risk scores may be adjusted for sequentially measured systolic inter-arm differences to take account of added risk. The data are derived from hazard ratios calculated from analyses publised in Hypertension 2021.

*Click on images for more information