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Variations in knowledge, awareness and treatment of hypertension and stroke risk by country income level
  1. Martin O' Donnell1,
  2. Graeme J Hankey2,
  3. Sumathy Rangarajan3,
  4. Siu Lim Chin3,
  5. Purnima Rao-Melacini3,
  6. John Ferguson4,
  7. Denis Xavier5,
  8. Liu Lisheng6,7,
  9. Hongye Zhang7,
  10. Prem Pais8,
  11. Patricio Lopez-Jaramillo9,
  12. Albertino Damasceno10,
  13. Peter Langhorne11,
  14. Annika Rosengren12,
  15. Antonio L Dans13,
  16. Ahmed Elsayed14,
  17. Alvaro Avezum15,
  18. Charles Mondo16,
  19. Andrew Smyth4,
  20. Conor Judge17,
  21. Hans-Christoph Diener18,
  22. Danuta Ryglewicz19,
  23. Anna Czlonkowska19,
  24. Nana Pogosova20,
  25. Christian Weimar21,22,
  26. Romana Iqbal23,
  27. Rafael Diaz24,
  28. Khalid Yusoff25,
  29. Afzalhussein Yusufali26,
  30. Aytekin Oguz27,
  31. Xingyu Wang28,
  32. Ernesto Penaherrera29,
  33. Fernando Lanas30,
  34. Okechukwu Samuel Ogah31,
  35. Adensola Ogunniyi32,
  36. Helle K Iversen33,
  37. German Malaga34,
  38. Zvonko Rumboldt35,
  39. Shahram Oveisgharan36,
  40. Fawaz AlHussain37,
  41. Magazi Daliwonga38,
  42. Yongchai Nilanont39,
  43. Salim Yusuf3
  1. 1HRB-Clinical Research Facility, National University of Ireland Galway, Galway, Ireland
  2. 2Medical School, Faculty of Health and Medical Sciences, University of Western Australia, Perth, Western Australia, Australia
  3. 3Dept of Medicine, Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada
  4. 4National University of Ireland Galway, Galway, Ireland
  5. 5St John's Research Insitiute, Bangalore, Karnataka, India
  6. 6National Center for Cardiovascular Diseases China, Xicheng District, Beijing, China
  7. 7Beijing Hypertension League Institute, Beijing, China
  8. 8St John's National Academy of Health Sciences, Bangalore, Karnataka, India
  9. 9Instituto de Investigaciones MASIRA, Universidad de Santander, Bucaramanga, Colombia
  10. 10Faculty of Medicine, Eduardo Mondlane University, Maputo, Mozambique
  11. 11Academic Section of Geriatric Medicine, Glasgow Royal Infirmary, University of Glasgow, Glasgow, UK
  12. 12Department of Molecular and Clinical Medicine, University of Gothenburg and Region Västra Götaland, Sahlgrenska University Hospital, Goteborg, Sweden
  13. 13University of the Philippines Manila College of Medicine, Manila, Metro Manila, Philippines
  14. 14Alzaiem Alazhari University, Khartoum, Sudan
  15. 15International Research Center, Hospital Alemão Oswaldo Cruz, São Paulo, Brazil
  16. 16Kiruddu National Referral Hospital, Kampala, Uganda
  17. 17Medicine, National University of Ireland Galway, Galway, Galway, Ireland
  18. 18Department of Neurology, University Hospital Essen, Essen, Nordrhein-Westfalen, Germany
  19. 19Military Institute of Aviation Medicine, Warsaw, Poland
  20. 20National Medical Research Center of Cardiology, Moscow, Russia, Moskva, Russian Federation
  21. 21Neurology, Institute for Medical Informatics, Biometry and Epidemiology, University of Duisburg-Essen, Essen, Germany
  22. 22BDH-clinic Elzach, Elzach, Germany
  23. 23Department of Community Health Sciences and Medicine, Aga Khan University, Karachi, Pakistan
  24. 24Estudios Clínicos Latino America (ECLA), Instituto Cardiovascular de Rosario (ICR), Rosario, Argentina
  25. 25Universiti Teknologi MARA, Selayang, Selangor and UCSI University, Kuala Lumpur, Malaysia
  26. 26Hatta Hospital, Dubai Health Authority/Dubai Medical College, Dubai, UAE
  27. 27Department of Internal Medicine, Istanbul Medeniyet University, Istanbul, Istanbul, Turkey
  28. 28Laboratory of Human Genetics, Beijing Hypertension League Institute, Beijing, China
  29. 29Department of Cardiology, Luis Vernaza General Hospital, Guayaquil, Guayas, Ecuador
  30. 30Internal Medicine, Universidad de La Frontera, Temuco, Chile
  31. 31Division of Cardiology, University of Ibadan, Ibadan, Oyo, Nigeria
  32. 32Neurology Unit, Department of Medicine, University College Hospital Ibadan, Ibadan, Oyo, Nigeria
  33. 33Department of Neurology, University of Copenhagen, Rigshospitalet, Denmark
  34. 34School of Medicine, Universidad Peruana Cayetano Heredia, Lima, Peru
  35. 35Department of Medicine, University of Split, Split, Splitsko-dalmatinska, Croatia
  36. 36Rush University Medical Center, Chicago, Illinois, USA
  37. 37King Saud University, Riyadh, Riyadh Province, Saudi Arabia
  38. 38Department of Medicine, University of Limpopo, Sovenga, Limpopo, South Africa
  39. 39Division of Neurology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
  1. Correspondence to Dr Martin O' Donnell, Clinical Research Facility, National University of Ireland Galway, Galway, Ireland; martin.odonnell{at}


Objective Hypertension is the most important modifiable risk factor for stroke globally. We hypothesised that country-income level variations in knowledge, detection and treatment of hypertension may contribute to variations in the association of blood pressure with stroke.

Methods We undertook a standardised case-control study in 32 countries (INTERSTROKE). Cases were patients with acute first stroke (n=13 462) who were matched by age, sex and site to controls (n=13 483). We evaluated the associations of knowledge, awareness and treatment of hypertension with risk of stroke and its subtypes and whether this varied by gross national income (GNI) of country. We estimated OR and population attributable risk (PAR) associated with treated and untreated hypertension.

Results Hypertension was associated with a graded increase in OR by reducing GNI, ranging from OR 1.92 (99% CI 1.48 to 2.49) to OR 3.27 (2.72 to 3.93) for highest to lowest country-level GNI (p-heterogeneity<0.0001). Untreated hypertension was associated with a higher OR for stroke (OR 5.25; 4.53 to 6.10) than treated hypertension (OR 2.60; 2.32 to 2.91) and younger age of first stroke (61.4 vs 65.4 years; p<0.01). Untreated hypertension was associated with a greater risk of intracerebral haemorrhage (OR 6.95; 5.61 to 8.60) than ischaemic stroke (OR 4.76; 3.99 to 5.68). The PAR associated with untreated hypertension was higher in lower-income regions, PAR 36.3%, 26.3%, 19.8% to 10.4% by increasing GNI of countries. Lifetime non-measurement of blood pressure was associated with stroke (OR 1.80; 1.32 to 2.46).

Conclusions Deficits in knowledge, detection and treatment of hypertension contribute to higher risk of stroke, younger age of onset and larger proportion of intracerebral haemorrhage in lower-income countries.

  • stroke
  • hypertension
  • epidemiology

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  • Contributors All authors contributed to the collection of data, discussions and interpretation of the data, and to the writing of the report. All authors reviewed and approved the manuscript for submission. The study was designed, the analyses were planned and the manuscript was drafted by MO’D and SY. Statistical analyses were performed by PR-M and JF. MO’D and SY wrote the first draft of the manuscript.

  • Funding The INTERSTROKE study is funded by the Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland, and through unrestricted grants from several pharmaceutical companies with major contributions from Astra Zeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MERCK, Sharp and Dohme], Swedish Heart and Lung Foundation, UK Chest, and UK Heart and Stroke.

  • Disclaimer No medical writer or other people were involved in the design, analysis or writing of this manuscript.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the ethics committees in all participating centres.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement No additional data are available.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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