Factors associated with elevated blood pressure or hypertension in Afro- Caribbean youth: a cross-sectional study TrevorS.Ferguson1, NovieO.M.Younger-Coleman1, MarshallK.Tulloch-Reid1, NadiaR.Bennett1, AmandaE.Rousseau1, JenniferM.Knight-Madden1, MaureenE.Samms-Vaughan2, DeannaE.Ashley3 and RainfordJ.Wilks1 1CaribbeanInstituteforHealthResearch,UniversityoftheWestIndies,Mona,Kingston,Jamaica 2DepartmentofChildHealth,UniversityoftheWestIndies,Mona,Kingston,Jamaica 3SchoolofGraduateStudiesandResearch,UniversityoftheWestIndies,Mona,Kingston,Jamaica ABSTRACT Background. Although several studies have identified risk factors for high blood pressure(BP),datafromAfro-Caribbeanpopulationsarelimited.Additionally,lessis knownabouthowputativeriskfactorsoperateinyoungadultsandhowsocialfactors influencetheriskofhighBP.Inthisstudy,weestimatedtherelativeriskforelevatedBP orhypertension(EBP/HTN),definedasBP≥120/80mmHg,amongyoungadultswith putative cardiovascular disease (CVD) risk factors in Jamaica and evaluated whether relativerisksdifferedbysex. Methods.Datafrom898youngadults,18–20yearsold,wereanalysed.BPwasmeasured with a mercury sphygmomanometer after participants had been seated for 5 min. Anthropometricmeasurementswereobtained,andglucose,lipidsandinsulinmeasured fromafastingvenousbloodsample.Dataonsocioeconomicstatus(SES)wereobtained viaquestionnaire.CVDriskfactorstatuswasdefinedusingstandardcut-pointsorthe upperquintileofthedistributionwherethenumbersmeetingstandardcut-pointswere small. Relative risks were estimated using odds ratios (OR) from logistic regression models. Submitted3October2017 Results. Prevalence of EBP/HTN was 30% among males and 13% among females Accepted 29January2018 (p<0.001forsexdifference).Therewasevidenceforsexinteractionintherelationship Published13February2018 between EBP/HTN and some of risk factors (obesity and household possessions), Correspondingauthor therefore we report sex-specific analyses. In multivariable logistic regression models, TrevorS.Ferguson, factors independently associated with EBP/HTN among men were obesity (OR 8.48, [email protected], [email protected] 95%CI[2.64–27.2],p<0.001),andhighglucose(OR2.01,CI[1.20–3.37],p=0.008), while high HOMA-IR did not achieve statistical significance (OR 2.08, CI [0.94– Academiceditor AntonioPalazón-Bru 4.58],p=0.069).Insimilarmodelsforwomen,hightriglycerides(OR1.98,CI[1.03– 3.81], p=0.040) and high HOMA-IR (OR 2.07, CI [1.03–4.12], p=0.039) were AdditionalInformationand Declarationscanbefoundon positivelyassociatedwithEBP/HTN.LowerSESwasalsoassociatedwithhigherodds page17 for EBP/HTN (OR 4.63, CI [1.31–16.4], p=0.017, for moderate vs. high household DOI10.7717/peerj.4385 possessions;OR2.61,CI[0.70–9.77],p=0.154forlowvs.highhouseholdpossessions). AlcoholconsumptionwasassociatedwithloweroddsofEBP/HTNamongfemalesonly; Copyright OR0.41(CI[0.18–0.90],p=0.026)fordrinking<1timeperweekvs.neverdrinkers, 2018Fergusonetal. and OR 0.28 (CI [0.11–0.76], p=0.012) for drinking ≥3 times per week vs. never Distributedunder drinkers. Physical activity was inversely associated with EBP/HTN in both males and CreativeCommonsCC-BY4.0 females. OPENACCESS HowtocitethisarticleFergusonetal.(2018),FactorsassociatedwithelevatedbloodpressureorhypertensioninAfro-Caribbeanyouth: across-sectionalstudy.PeerJ6:e4385;DOI10.7717/peerj.4385 Conclusion.FactorsassociatedwithEBP/HTNamongJamaicanyoungadultsinclude obesity, high glucose, high triglycerides and high HOMA-IR, with some significant differencesbysex.AmongwomenlowerSESwaspositivelyassociatedwithEBP/HTN, whilemoderatealcoholconsumptionwasassociatedloweroddsofEBP/HTN. SubjectsCardiology,Epidemiology,GlobalHealth,InternalMedicine,PublicHealth Keywords Elevatedbloodpressure,Hypertension,Cardiovasculardiseaseriskfactors,Young adults,Caribbean,Blacks,Jamaica,Socioeconomicstatus,Prehypertension INTRODUCTION High blood pressure (BP) is the leading risk factor for the global burden of disease, accountingforapproximately7%ofglobaldisabilityadjustedlifeyears(Limetal.,2012). Recent studies suggest that while the prevalence of hypertension is decreasing in high- incomecountries,prevalenceisincreasinginlowandmiddle-incomecountries,withthe largestincreaseseenincountriesinsub-SaharanAfrica(Millsetal.,2016;NCDRiskFactor Collaboration,2016).TheadverseeffectofhighBP,particularlyincreasedriskofcoronary heartdiseaseandstroke,iscontinuousandgradedthroughouttherangeofsystolicblood pressure (SBP) and diastolic blood pressure (DBP), down to levels of 115 mmHg and 75 mmHg, respectively (Lewingtonetal.,2002). Additionally, it has been estimated that approximately 50% of disease burden attributable to high BP occurs at levels below the 140/90mmHgcut-offpointtraditionallyusedtodefinehypertension(Poulter,Prabhakaran &Caulfield,2015). Recently the American College of Cardiology and American Heart Association(ACC/AHA)proposednewguidelinesfortheevaluationandmanagementof high BP (Wheltonetal.,2017). In this guideline, normal BP is defined having SBP <120 mmHgandDBP<80mmHg;elevatedBPisdefinedasSBPof120-129mmHgandDBP <80mmHg;andhypertensiondefinedasSBP≥130mmHgorDBP>80mmHg.However, most of the available data on prevalence of hypertension have used the criteria from the SeventhReportoftheJointNationalCommitteeonthePrevention,Detection,Evaluation and Treatment of High Blood Pressure (JNC 7), where hypertension is defined as SBP ≥140mmHgorDBP≥90mmHg,andSBPof120-139mmHgorDBPof80-89isclassified as prehypertension (Chobanianetal.,2003). Studies reporting prevalence estimates for children or adolescents <18 years old often use criteria from The Fourth Report on the Diagnosis,Evaluation,andTreatmentofHighBloodPressureinChildrenandAdolescents by the National High Blood Pressure Education Program (NHBPEP) (NationalHigh BloodPressureEducationProgramWorkingGrouponHighBloodPressureinChildrenand Adolescents,2004). Reportedprevalenceofhypertension,usingJNC7orNHBPEPcriteria,inadolescents andyoungadultsvarywidely,withestimatesgenerallyrangingfromabout2%among15–34 year-olds in Italy up to 19% among young adults 24–34 years old in the USA (Battistoni etal.,2015).However,prehypertensionappearstobecommoninadolescentsandyoung adults,withprevalenceestimatesrangingfrom12%–45%invariousstudiesfromcountries such as India, Uganda, United States and Jamaica (Amma,Vasudevan&Akshayakumar, Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 2/26 2015;Fergusonetal.,2011b;Kayimaetal.,2015;Kinietal.,2016;Redwine&Daniels,2012). GiventhathighBPinchildhoodhasbeenshowntotrackintoadulthood(Baoetal.,1995; Chen&Wang,2008),studiesofhighBPinyouthprovideessentialinformationtoinform interventionsthatwouldreducetheadverseeffectsofhighBPoncardiovascularhealth. The aetiology of hypertension is multi-factorial, with complex interactions between genetic,environmental,behaviouralandsocialfactors(Lloyd-Jones&Levy,2013;Poulter, Prabhakaran&Caulfield,2015; Victor,2015). Established risk factors for hypertension include increasing age, higher levels of adiposity, high dietary sodium, high alcohol consumption,familyhistoryofhypertensionandlowersocioeconomicstatus(Lloyd-Jones &Levy,2013). Underlying mechanism include activation of the sympathetic nervous system, disorders of the renin-angiotensin aldosterone pathways, disorders of renal regulation of sodium balance, insulin resistance, inflammation, arterial stiffness and foetalprogramming(Acelajado,Calhoun&Oparil,2013;Victor,2015). Complications of hypertension vary with race/ethnicity and it is conceivable that the mechanisms underlying both aetiology and complications could vary similarly (Jones& Hall,2006; Lackland,2014). Additionally, less is known about how these factors operate in young African origin populations and how social factors, particularly in a developing countrycontext,influencetheriskofhighBP. In Jamaica, the prevalence of hypertension (using the JNC 7 criteria) among persons 15–74 years old was estimated at 20% in 2001, and 25% in 2008 (Fergusonetal.,2011a). The prevalence of prehypertension was 30% in 2001 and 35% in 2008, and was shown to be associated with other cardiovascular disease (CVD) risk factors and high rates of progression to hypertension (Fergusonetal.,2011a; Fergusonetal.,2010c; Fergusonetal., 2008). Among 15–19 year-old youth, the prevalence of prehypertension in 2006 was 29%(Fergusonetal.,2011b).Morerecently,theModelingtheEpidemiologicalTransition StudyreportedprevalenceofhypertensionamongurbanJamaicans25–45yearsold,with prevalence estimates of 6.8% among men and 10% among women (Cooperetal.,2015). ThisstudyalsofoundthattheprevalenceofCVDriskfactorswasnotalwaysconsistentwith thatexpected,withJamaicanwomenhavinglowerdiabetesprevalencedespitehighobesity prevalenceandSouthAfricanmenhavinghigherprevalenceofhypertensiondespitelower adiposity(Dugasetal.,2017).Giventhehighburdenofhypertensionandprehypertension inJamaica,studiesevaluatingtherelativecontributionofvariousriskfactorswouldprovide necessaryinformationtodirectpublichealthinterventions.Thispaperthereforeevaluates theassociationbetweenputativeriskfactorsandelevatedBPorhypertension(EBP/HTN), defined as BP ≥120/80 mmHg, among Afro-Caribbean youth. Specifically, we aimed to estimatetherelativeriskforhavingEBP/HTNamongparticipantswithputativeCVDrisk factors, and to evaluate whether there were significant sex differences in risk factors for EBP/HTN. METHODS Data sources Weconductedacross-sectionalanalysisusingdatafromthethirdfollowupoftheJamaica 1986 Birth Cohort Study (Fergusonetal.,2010a; McCaw-Binnsetal.,2011). This study Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 3/26 is a longitudinal study of persons, born in Jamaica in September and October of 1986, and who were a part of the Jamaica Perinatal Mortality Survey (Ashley,McCaw-Binns& Foster-Williams,1988).Detailsonthiscohorthavebeenpreviouslypublished(Bennettet al.,2014;McCaw-Binnsetal.,2011).Forthisanalysis,weuseddatafrom409malesand489 females,18–20yearsold,collectedinthethirdfollowupofthecohortbetweenMarch2005 andFebruary2007.ThestudywasapprovedbytheUniversityoftheWestIndies/Faculty of Medical Sciences Ethics Committee. Participants provided written informed consent priortomeasurementsbeingdone. Measurements and definitions Alldatacollectionandmeasurementsweredonebytrainedresearchnurses.Weobtained data on demographic characteristics, general health, medical history, behavioural health risk factors and socioeconomic status via questionnaire. Additionally, we obtained anthropometricandBPmeasurementsandperformedvenepunctureforanalysisofblood glucose,lipids,insulinandcreatinine.Atimedurinesamplewasobtainedformeasurement ofurinaryalbuminexcretion. BP was measured with a mercury sphygmomanometer after the participant had been seated for 5 min. BP measurement followed a standardized protocol developed for the InternationalCollaborativeStudyofHypertensioninBlacks(Atamanetal.,1996).Three BPmeasurementsweretakenat1-minuteintervals,withthemeanofthesecondandthird measurements being used for analysis. EBP/HTN was defined as SBP ≥120 mmHg or DBPof≥80mmHg,correspondingtotheprehypertensionandhypertensioncategoriesof JNC7andtheelevatedBPandhypertensioncategoriesofthe2017ACC/AHAguidelines (Chobanianetal.,2003;Wheltonetal.,2017).Noneoftheparticipantswereonmedication forelevatedbloodpressureatthetimeofassessment. Weightwasmeasuredusingaportabledigitalscale,whichwascalibrateddaily.Height wasmeasuredusingaportablestadiometer.Waistandhipcircumferenceweremeasured using a non-stretchable nylon tape measure. Body mass index (BMI) was calculated as weight in kilograms divided by the square of height in metres and BMI categories definedusingtheWorldHealthOrganizationcategories:underweight(BMI<18.5kg/m2), normal weight (BMI 18.5–24.9 kg/m2), overweight (BMI 25.0–29.9 kg/m2), obese (BMI ≥30 kg/m2) (WorldHealthOrganization, 1995). The normal weight category was used as the reference group. Central obesitywas defined as a waist circumference≥80 cm for womenand≥94cmformenasrecommendedforAfricanOriginpopulationsinthe2009 Consensus Criteria for the Metabolic Syndrome (Albertietal.,2009). Waist-to-hip ratio was calculated by dividing waist circumference by hip circumference. High waist-to-hip ratiowasdefinedusingcut-pointsrecommendedbyLean,Han&Morrison(1995)as≥0.95 formalesand≥0.80forfemales. Venousbloodwascollectedafteranovernightfastofatleasteighthours.Sampleswere analysed using standard laboratory protocols for measurement of fasting glucose, lipids, fastinginsulinandserumcreatinine.WhitebloodcellcountandhighsensitivityC-reactive protein(hsCRP)weremeasuredasmarkersofinflammation. Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 4/26 Details of laboratory procedures have been previously published (Bennettetal.,2014; Fergusonetal.,2010a; Rockeetal.,2015; Tulloch-Reidetal.,2010). In brief, glucose was measured using the glucose oxidase method (Alcyon, Analyzer); total cholesterol, triglycerides,andhighdensitylipoproteincholesterol(HDL)weremeasureddirectlyusing enzymaticmethods(AbbottSpectrumAnalyzer),whilelowdensitylipoproteincholesterol (LDL)wascalculatedusingtheFriedewaldequation(totalcholesterol−HDL−[TG/2.18], with all concentrations given in mmol/L). Serum creatinine was measured using Jaffe’s reactionontheAlcyon300ChemistryAnalyser(Abbott,Chicago,IL,USA),whilefasting insulin was measured using a chemiluminescent immunoassay (IMMULITE; Diagnostic ProductsCorporation,LosAngeles,CA,USA);hsCRPwasmeasuredusinganIMMULITE immunoassay (Siemens Medical Solution Diagnostics, Los Angeles, CA). Microalbumin was measured from a timed urine specimen using a chemiluminescent immunoassay methodusingtheIMMULITEImmunoassaySystem(Siemens,LosAngeles,CA). Elevatedglucose(≥5.6mmol/L),elevatedtriglycerides(≥1.7mmol/L)andlowlevelsof highdensitylipoproteincholesterol[HDL](<1.0mmol/Lformalesand<1.3mmol/Lfor females)weredefinedusingthemetabolicsyndromecriteria(Albertietal.,2009).Hightotal cholesterol (≥5.2 mmol/L) and high levels of low density lipoprotein [LDL] cholesterol (≥4.1 mmol/L) were defined using the National Cholesterol Education Program Adult TreatmentPanelIII(ATPIII)criteria(ExpertPanelonDetectionEvaluationandTreatment ofHighBloodCholesterolinAdults,2001).Foranalysesincludingglucoseandtriglycerides values in the upper quintile of the distribution were defined as elevated, because the proportion of participants meeting the metabolic syndrome cut-points was very small, thusresultingintoofewparticipantsformultivariableanalyses.HighhsCRPwasdefined as >3.0 mg/L, with values >10 mg/L set to missing, as recommended by the American HeartAssociationandCentersforDiseaseControl(Pearsonetal.,2003).Insulinresistance wasestimatedusingtheHomeostasisModelAssessment(HOMA-IR)equations(Matthews etal.,1985). Values for HOMA-IR were log transformed to account for non-normal distribution. Elevated HOMA-IR was classified as being in the upper quintile of the log-HOMA-IR. For this paper we chose to dichotomize these characteristics in order to quantifytheeffectofbeinginanabnormal(highrisk)categoryandfacilitatethetailoring of public health messages aimed at risk reduction. Urine albumin and creatinine levels wereusedtocalculatethealbumintocreatinineratio(ACR)andelevatedurinealbumin definedasACR≥30mg/gasrecommendedbythe2012KidneyDiseaseImprovingGlobal Outcomes (KDIGO) Guidelines (KidneyDisease:ImprovingGlobalOutcomes(KDIGO) CKDWorkGroup,2013). Socioeconomic status was assessed using data collected using a locally developed questionnaire on parental education and occupation, and number of household possessions. The specific questionnaire items are included in the supplementary files availableonline.Dataoneducationwascollectedasthehighestlevelofeducationattained by either parent or guardian and then categorized as: post-secondary, secondary, or less than secondary. In Jamaica, children are required to complete a mandatory six years of elementary school (Grades 1–6) and five years of high school (Grades 7–11 or first to fifth form), after which they graduate from high school. Children may spend an extra Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 5/26 two years in sixth form (Grades 12 and 13) before going on to university or college. In this classification, post-secondary education includes persons who completed college or university and persons with vocational training obtained after completing high school. Secondaryeducationindicatespersonswhocompletedhighschool(uptograde11)and lessthansecondaryincludespersonswhodidnotcompletehighschool(i.e.,highschool education up to grade 10 or below). Occupational categories were defined using the occupation of the household head and coded using the Jamaica Standard Occupational Classification (JSOC) (StatisticalInstituteofJamaica,1995). For this report occupation categories were classified as professionals or managers, office, service or trade workers, andsemi-skilledorunskilledworkers.Forhouseholdpossessions,participantswereasked toindicatewhethertheyhaditemsfromalistof17householdpossessionsandgivenone point for each item. They were then classified in three possession score categories based on the distribution of items: low (0–9 items), moderate (10–14 items), and high (15–17 items). The list of items included in the possession score is shown Table S1. Cut-points for this classification was chosen based on the finding that the majority of participants had10–14items,sothatthegroupswith0–9itemswouldrepresentthelowerendofthe distributionand15–17itemstheupperendofthedistribution. Dataonphysicalactivity,smoking(cigarettesormarijuana)andalcoholconsumption werealsocollectedviaquestionnaire.Forsmoking,participantswereclassifiedascurrent smokers or non-smokers, while for alcohol consumption participants were classified as: ‘neverdrankalcohol’,‘rarelydrinksalcohol’(<1timeperweek),‘drinksalcohol1–2times per week’, or ‘drinks alcohol ≥3 times per week’. Physical activity was classified based on the time spent doing sports or exercise during leisure time using a locally developed questionnaire.Questionnaireitemsincludedquestionsontimespentdoingactivesports orotheractivitiessuchasbriskwalking,jogging,liftingweights,danceclasses,andworkout atagym.Thespecificquestionnaireitemsareincludedintheonlinesupplementaryfiles. Physicalactivityassessedusingthisquestionnairewasshowntobemorestronglyassociated with measures of obesity than the International Physical Activity Questionnaire (IPAQ) (Youngeretal.,2007).Participantswithnoleisuretimephysicalactivitywereclassifiedas low physical activity level, those with <3.5 h per week as moderate physical activity level andthosewith3.5hormoreperweekashighphysicalactivitylevel. Sample size and power Giventhatwehadafixedavailablesamplesizeof409malesand489femalesandthatwe performedsex-specificanalyses,weestimatedthemaximumdetectableoddsratioinstead ofsamplesize.Theseestimateswerecomputedformalesandfemales,separately,usingthe power twoproportions command available in Stata 14 (StataCorp, 2015c). We estimated theprevalenceoftheoutcomevariable(EBP/HTN),fromthesampleat30%formalesand 13%forfemales,andusedtheseandtheavailablesamplesizetocomputethemaximum detectableoddsratioforexposures,withproportionexposedrangingfrom0.1to0.5for power of 80% at the 5% significance level. For males, the given sample size of 409 had 80%powertodetectoddsratioof1.84iftheproportionexposedwas0.5and2.13ifthe Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 6/26 proportion exposed was 0.2. For females the given sample size of 489 had 80% power to detect odds ratio of 2.02 if the proportion exposed was 0.5 and 2.34 if the proportion exposedwas0.2. Statistical methods WeperformeddataanalysiswithStataversion14.1software(StataCorp.,CollegeStation, TX, USA). We obtained descriptive statistics (means and proportions) for outcome and explanatory variables within and across sex and blood pressure categories. If data were highly skewed, we reported the median and interquartile range instead of the mean and standard deviation. Proportions were compared using the Pearson’s chi-squared test or Fisher’s exact tests, as appropriate. Differences in means were compared using the unequal variance two sample t-test. Differences in medians were compared using the non-parametricequalityofmediantestavailableinStata(StataCorp,2015a). Logistic regression and two-way analysis of variance (ANOVA) models were used to determine if there was evidence for sex interaction in the relationship between BP and some of the explanatory variables. Results for analyses assessing interaction using the logisticregressionmodelsareshowninTableS2.Therewasevidenceforsexinteractionin therelationshipbetweenEBP/HTNandsomeofriskfactors(obesity,centralobesityand householdpossessions),thereforewereportsex-specificresultsforregressionanalyses. Weusedmultipleimputationbychainedequationstoaccountformissingdataforsome explanatoryvariables.Theproportionofcompletecases,i.e.,participantswithnomissing valuesforanyofthevariablesofinterest,was43%(n=384);Themajorityofincomplete cases(30%ofparticipants)hadonlyhadonemissingvalue;14%hadtwomissingvalues, 7% had three missing values and 7% had more than three missing values. Details on the number of missing values for each variable are shown in Table S3. A comparison of thecompletecasesvs.theincompletecasesrevealedonlyminordifferences.Participants with missing values were more likely to have albuminuria, fewer household possessions, lowerphysicalactivityandloweralcoholconsumption,buthadnostatisticallysignificant differencesforanyothercharacteristics.Giventheproportionofparticipantswithatleast one missing value and the observed differences between complete and incomplete cases, multipleimputationwasusedtoimprovethepowerofthestudyandreducebiasthatmay beseeninthecompletecaseanalysis(Nguyen,Carlin&Lee,2017;White,Royston&Wood, 2011).Astackedmultipleimputeddataset,consistingoftheoriginaldatasetand25data setswithimputationsformissingvalues,wascreatedusingStata’smisuiteofcommands (StataCorp,2015b).Wecomparedimputedvariablevaluestotheobservedvaluestoensure thattheimputedvalueswereplausible;thesedataareshowninTableS4. Bivariate logistic regression was used to assess the association between EBP/HTN and individual explanatory variables. These bivariate models were estimated using Stata’s mi suiteofcommandsandestimatescombinedbythesoftwareusingRubinrules(Marshall etal.,2009;StataCorp,2015b).Foruseinmodelselection,weextractedthefirstofthe25 imputeddatasetsandperformedregularbinarylogisticregressiononthesingle-imputed data,asrecommendedbyWood,WhiteandRoyston(Wood,White&Royston,2008).We Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 7/26 used the backwards stepwise regression algorithm available in Stata to identify variables for inclusion in the final model. All variables hypothesized to be associated with the outcome were included in the first multivariable model and p-value > 0.2 was used to removevariablesfromthemodel.WethenusedthePearsonandHosmer-Lemeshowtests for goodness-of-fit to assess the models. Finally, we used Akaike information criterion (AIC)todeterminewhethertoincludeorexcludespecificvariablesfromthefinalmodels. Final multivariable models were then run on the multiple imputed data set with 25 imputations,usingStata’smisuiteofcommandsandestimatescombinedbythesoftware usingRubinrules(Marshalletal.,2009;StataCorp,2015b).Toassessthepotentialimpact of the imputed values on the final conclusions we also re-ran the final models without imputations(i.e.,completecaseanalysis);theseresultsareshowninTableS5. RESULTS SummarystatisticsfordemographicandbiomedicalmeasurementsareshowninTable1. Mean age at the time of the study was 18.8 years (SD = 0.61), with no sex difference. Comparedtofemales,maleshadhighermeanweight,height,SBP,DBP,fastingglucose, triglycerides and creatinine, while females had higher mean total cholesterol, LDL and HDL cholesterol. Females also had higher median hsCRP, fasting insulin concentration andHOMA-IR.Comparisonsofparticipants’characteristicsbyBPcategoriesareshownin TableS6.Overall,participantswithEBP/HTNtendedtohavehighermeanvaluesofCVD riskfactors. Proportions of participants with EBP/HTN and other CVD risk factors, expressed as categoricalvariables,areshownisTable2.OverallprevalenceofEBP/HTNwas21%and wastwiceashighinmencomparedtowomen(30%vs.13%,p<0.001).Theprevalenceof elevatedBP(SBP120–129mmHg,DBP<80mmHg)was9%(13%amongmalesand5% amongfemales,p<0.001),whilehypertension(BP≥130/80mmHg)prevalencewas12% (17%amongmalesand8%amongfemales,p<0.001).Prevalenceofobesitywas8%(6% amongmalesand10%amongfemales,p=0.008).Themajorityofparticipantswerefrom middle-income households, with the household head having completed secondary level educationandworkingasoffice,service,ortradeworkers.Lowphysicalactivitylevelwas reportedby34%ofparticipantsandhighphysicalactivityby24%.Thereweresignificant sex differences in physical activity among males compared to females (p<0.001) with 47%offemalesreportinglowphysicalactivitylevelscomparedto18%amongmales,while high physical activity was reported by 38% of males compared to 13% among females. Cigarette smoking was reported by 14% of males and 6% of females (p<0.001), while 31% of males and 7% of females smoked marijuana (p<0.001). Males also reported higherlevelsofmoderate(≥3times/week)alcoholconsumption(38%vs.19%,p<0.001). SimilaranalysesstratifiedbyBPcategoryareshowninTableS7.Significantdifferenceby blood pressure category were seen for BMI categories, central obesity and waist-to-hip ratioamongmales,andfornumberofhouseholdpossessionsamongfemales. Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 8/26 Table1 Meanormedianvaluesforparticipantcharacteristicsandputativehypertensionriskfactors formales,femalesandbothsexes. Characteristic Male Female Bothsexes n=409 n=489 N =898 Mean±SD Mean±SD Mean±SD Age(years) 18.8±0.59 18.8±0.62 18.8±0.61 Weight(kg)*** 71.1±14.2 62.4±15.5 66.4±15.5 Height(cm)*** 176.8±6.5 163.6±6.1 169.6±9.1 Bodymassindex(kg/m2) 22.7±4.3 23.3±5.6 23.0±5.0 Systolicbloodpressure(mmHg)*** 113.9±10.4 107.4±8.8 110.3±10.1 Diastolicbloodpressure(mmHg)*** 69.2±10.3 66.9±9.2 67.9±9.8 Waistcircumference(cm) 75.2±10.8 73.9±12.1 74.5±11.5 Hipcircumference(cm)** 94.4±8.9 96.5±11.0 95.5±10.2 Waist-to-Hipratio*** 0.80±0.08 0.77±0.14 0.78±0.12 Whitebloodcellcount(cells×109/L)*** 5.3±1.6 6.4±2.0 5.9±1.9 Fastingglucose(mmol/L)*** 4.7±0.6 4.4±0.4 4.6±0.5 Totalcholesterol(mmol/L)*** 4.1±0.8 4.5±0.9 4.3±0.9 HDLcholesterol(mmol/L)*** 1.1±0.2 1.2±0.3 1.2(0.3) LDLcholesterol(mmol/L)*** 2.7±0.7 3.0±0.8 2.9±0.8 Triglycerides(mmol/L)* 0.60±0.26 0.56±0.26 0.58±0.26 Creatinine(µmol/L)*** 80.5±16.0 56.9±25.5 67.7±24.7 Median(IQR) Median(IQR) Median(IQR) Urinaryalbumin(mg/g)* 3.9(2.5,7.4) 4.9(2.5,10.7) 4.1(2.5,9.2) hsCRP(mg/L)*** 0.5(0.3,1.3) 0.9(0.3,2.3) 0.7(0.3,1.8) Fastinginsulin(pmol/L)*** 4.4(2.7,7.1) 6.8(4.1,10.1) 5.8(3.3,8.8) HOMA-IR*** 0.6(0.3,0.9) 0.9(0.5,1.3) 0.7(0.4,1.1) Notes. *p<0.05. **p<0.01. ***p<0.001. SD, standarddeviation; HDL, highdensitylipoprotein; LDL, lowdensitylipoprotein; IQR, interquartilerange(values correspondtothe25thand75thcentiles); hsCRP, highsensitivityC-reactiveprotein; HOMA-IR, HomeostasisModel Assessment—InsulinResistance. Differencesinmeanswerecomparedusingthetwo-samplettestwithunequalvariances,whilethedifferencesinmedianswere computedusingthenonparametricequality-of-medianstest. Theresultsfrombivariateanalysesyieldingsexspecificoddsratiosfortherelationship between correlates and putative risk factors for EBP/HTN are shown in Table 3. Factors associated with EBP/HTN among males in bivariate analyses were: age, obesity, central obesity,highglucose,hightriglyceridesandhighHOMA-IR.Amongfemales,significant correlateswereage,height,hightriglycerides,highHOMA-IRandnumberofhousehold possessions. There were no significant associations for general or central obesity among females,andnosignificantassociationsformeasuresofinflammation(hsCRPandwhite bloodcellcount)orurinealbuminexcretionineithersex. Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 9/26 Table2 ProportionofparticipantsincategoriesforbloodpressureandotherCVDriskfactorsfor males,femalesandbothsexes. Characteristic Male Female Bothsexes n=409 n=489 N =898 %(n) %(n) %(n) ElevatedBPorhypertension(BP≥120/80mmHg)*** 29.8(122) 13.4(66) 20.9(188) ElevatedBP(SBP120–129&DBP<80mmHg)*** 13.2(54) 5.3(26) 8.9(80) Hypertension(BP≥130/80)*** 16.6(68) 8.2(40) 12.0(108) Stage1hypertension(BP130–139/80–89)*** 14.7(60) 7.4(36) 10.7(96) Stage2hypertension(BP≥140/90) 2.0(8) 0.8(4) 1.3(12) Albuminuria 5.1(20) 8.3(39) 6.8(59) Bodymassindexcategories*** Underweight (<18.5kg/m2) 6.1(25) 14.5(71) 10.7(96) Normalweight (18.5–24.9kg/m2) 76.3(308) 55.2(270) 64.4(578) Overweight (25–29.9kg/m2) 13.0(53) 19.8(87) 16.7(150) Obese(≥30kg/m2) 5.6(23) 10.4(51) 8.2(74) Centralobesitya,*** 5.1(21) 24.4(119) 15.6(140) Highwaist-to-hipratiob,*** 1.0(4) 20.3(99) 11.5(103) HighestEducationofParent/Guardianc Post-secondary 26.2(89) 29.8(131) 28.2(220) Secondary 61.8(210) 55.4(243) 58.2(453) Lessthansecondary 12.1(41) 14.8(65) 13.6(106) Occupationofhouseholdhead Professionals/Managers 23.5(88) 24.7(114) 24.1(202) Office,serviceortradeworkers 49.3(185) 50.9(235) 50.2(420) Semi-skilled/Unskilledworkers 27.2(102) 24.5(113) 25.7(215) Numberofhouseholdpossession High(15–17items) 16.9(69) 13.7(67) 15.2(136) Moderate(10–14items) 56.9(232) 54.2(265) 55.4(497) Low(0–9items) 26.2(107) 32.1(157) 29.4(264) Physicalactivitylevel*** High 37.5(153) 13.1(64) 24.2(217) Moderate 44.4(181) 39.5(193) 41.7(374) Low 18.1(74) 47.4(232) 34.1(306) Currentcigarettesmoking*** 13.7(56) 6.1(30) 9.6(86) Currentmarijuanasmoking*** 31.3(127) 7.2(35) 18.1(162) Alcoholconsumption*** Neverdrankalcohol 6.4(26) 13.2(64) 10.1(90) Rarelydrinksalcohol 26.4(107) 45.2(219) 36.6(326) Drinksalcohol1–2times/week 29.1(118) 22.3(108) 25.4(226) Drinksalcohol ≥3times/week 38.0(154) 19.4(94) 27.9(248) Notes. *p<0.05. **p<0.01. ***p<0.001. BP, bloodpressure; SBP, systolicbloodpressure; DBP, diastolicbloodpressure; CVD, cardiovasculardisease. aCentralobesitydefinedaswaistcircumference≥94cminmalesand≥80cminfemales. bHighwaist-to-hipratio≥0.95formalesand≥0.80forfemales. cEducationcategory‘‘post-secondary’’includespersonswithvocationaltraining,college,oruniversityeducation;secondary correspondstohighschool(uptograde11);lessthansecondarycorrespondstopersonswhohadonlyelementaryschooledu- cationorpersonswhodidnotcompletehighschool(i.e.,highschoolgrade10orbelow). Fergusonetal. (2018),PeerJ,DOI10.7717/peerj.4385 10/26