title: The burden of hypertension in sub-Saharan Africa: a four-country cross sectional study.
abstract: BACKGROUND
  Hypertension, the leading single cause of morbidity and mortality worldwide, is a growing public health problem in sub-Saharan Africa (SSA). Few studies have estimated and compared the burden of hypertension across different SSA populations. We conducted a cross-sectional analysis of blood pressure data collected through a cohort study in four SSA countries, to estimate the prevalence of pre-hypertension, the prevalence of hypertension, and to identify the factors associated with hypertension.
  
  
  METHODS
  Participants were from five different population groups defined by occupation and degree of urbanization, including rural and peri-urban residents in Uganda, school teachers in South Africa and Tanzania, and nurses in Nigeria. We used a standardized questionnaire to collect data on demographic and behavioral characteristics, injuries, and history of diagnoses of chronic diseases and mental health. We also made physical measurements (weight, height and blood pressure), as well as biochemical measurements; which followed standardized protocols across the country sites. Modified Poison regression modelling was used to estimate prevalence ratios (PR) as measures of association between potential risk factors and hypertension.
  
  
  RESULTS
  The overall age-standardized prevalence of hypertension among the 1216 participants was 25.9%. Prevalence was highest among nurses with an age-standardized prevalence (ASP) of 25.8%, followed by school teachers (ASP = 23.2%), peri-urban residents (ASP = 20.5%) and lowest among rural residents (ASP = 8.7%). Only 50.0% of participants with hypertension were aware of their raised blood pressure. The overall age-standardized prevalence of pre-hypertension was 21.0%. Factors found to be associated with hypertension were: population group, older age, higher body mass index, higher fasting plasma glucose level, lower level of education, and tobacco use.
  
  
  CONCLUSIONS
  The prevalence of hypertension and pre-hypertension are high, and differ by population group defined by occupation and degree of urbanization. Only half of the populations with hypertension are aware of their hypertension, indicating a high burden of undiagnosed and un-controlled high blood pressure in these populations.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda. dguwatudde@musph.ac.ug.
authors.forename: David
authors.initials: D
authors.lastname: Guwatudde
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda. eron.jm@hotmail.com.
authors.forename: Joan
authors.initials: J
authors.lastname: Nankya-Mutyoba
authors.affiliation: Department of Medicine, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda. rkalyes@yahoo.com.
authors.forename: Robert
authors.initials: R
authors.lastname: Kalyesubula
authors.affiliation: Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa. carienl@sun.ac.za.
authors.forename: Carien
authors.initials: C
authors.lastname: Laurence
authors.affiliation: Institute of Human Virology, Abuja, Nigeria. adebamowo@outlook.com.|Greenbaum Cancer Center and Institute of Human Virology, University of Maryland, School of Medicine, Baltimore, MD, USA. adebamowo@outlook.com.
authors.forename: Clement
authors.initials: C
authors.lastname: Adebamowo
authors.affiliation: Institute of Human Virology, Abuja, Nigeria. ikeajayi2003@yahoo.com.|Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria. ikeajayi2003@yahoo.com.
authors.forename: IkeOluwapo
authors.initials: I
authors.lastname: Ajayi
authors.affiliation: Department of Community Health, Mbarara University Of Science and Technology, Mbarara, Uganda. fbaj@yahoo.com.
authors.forename: Francis
authors.initials: F
authors.lastname: Bajunirwe
authors.affiliation: Department of Physiology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania. madaula@yahoo.com.
authors.forename: Marina
authors.initials: M
authors.lastname: Njelekela
authors.affiliation: Department of Physiology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania. fschiwanga@yahoo.com.
authors.forename: Faraja S
authors.initials: FS
authors.lastname: Chiwanga
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. reid1001@gmail.com.
authors.forename: Todd
authors.initials: T
authors.lastname: Reid
authors.affiliation: Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa. jvolmink@sun.ac.za.|The South African Cochrane Centre, South African Medical Research Council, Cape Town, South Africa. jvolmink@sun.ac.za.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Volmink
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. hadami@hsph.harvard.edu.|Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden. hadami@hsph.harvard.edu.
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. michelle.holmes@channing.harvard.edu.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. michelle.holmes@channing.harvard.edu.
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Holmes
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. shonadalal@gmail.com.
authors.forename: Shona
authors.initials: S
authors.lastname: Dalal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001794:Blood Pressure; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D009726:Nurses; D009790:Occupations; D058246:Prehypertension / Q000453:epidemiology / Q000209:etiology; D015995:Prevalence; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D013636:Tanzania / Q000453:epidemiology; D013663:Teaching; D014454:Uganda / Q000453:epidemiology; D014505:Urban Population; D014507:Urbanization; D055815:Young Adult