Epidemiology/Population Science. Social Epidemiology of Hypertension in Middle-Income Countries

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1 Epidemiology/Populatio Sciece Social Epidemiology of Hypertesio i Middle-Icome Coutries Determiats of Prevalece, Diagosis, Treatmet, ad Cotrol i the WHO SAGE Study Sajay Basu, Christopher Millett Abstract Large-scale hypertesio screeig campaigs have bee recommeded for middle-icome coutries. We sought to idetify sociodemographic predictors of hypertesio prevalece, diagosis, treatmet, ad cotrol amog middleicome coutries. We aalyzed data from adults i all 6 middle-icome coutries (Chia, Ghaa, Idia, Mexico, Russia, ad South Africa) sampled i atioally represetative household assessmets from 2007 to 2010 as part of the World Health Orgaizatio Study o Global Agig ad Adult Health. We estimated regressio models accoutig for age, sex, urba/rural locatio, utritio, ad obesity, as well as hypothesized covariates of healthcare access, such as icome ad isurace. Hypertesio prevalece varied from 23% (Idia) to 52% (Russia), with betwee 30% (Russia) ad 83% (Ghaa) of hypertesives udiagosed before the survey ad betwee 35% (Russia) ad 87% (Ghaa) utreated. Although the risk of hypertesio sigificatly icreased with age (odds ratio, 4.6; 95% cofidece iterval, ; amog aged, versus <40 years), the risk of beig udiagosed or utreated fell sigificatly with age. Obesity was a sigificat correlate to hypertesio (odds ratio, 3.7; 95% cofidece iterval, for obese versus ormal weight), ad was prevalet eve amog the lowest icome quitile (13% obesity). Isurace status ad icome also emerged as sigificat correlates to diagosis ad treatmet probability, respectively. More tha 90 hypertesio cases were ucotrolled, with me havig 3 times the odds as wome of beig ucotrolled. Overall, the social epidemiology of hypertesio i middle-icome coutries seems to be correlated to icreasig obesity prevalece, ad hypertesio cotrol rates are particularly low for adult me across distict cultures. (Hypertesio. 2013;62:18-26.) Olie Data Supplemet Key Words: developig coutries epidemiology health disparities hypertesio Hypertesio is the leadig risk factor for mortality worldwide, ad is commo i low- ad middle-icome coutries. 1 Although hypertesio i developig coutries has bee the subject of substatial research, 2 4 may critical questios remai uaddressed. Specifically, prior assessmets of hypertesio prevalece i developig atios have usually bee based o imputed prevalece calculatios, 5 which may be biased (oversamplig populatios with access to medical care), ad fail to iform policymakers about sigificat withipopulatio health disparities (eg, iequalities i risk related to icome or healthcare access). 6,7 The commo rule of halves i hypertesio epidemiology suggests that about half of hypertesive populatios are diagosed, half of those diagosed are treated, ad half of those treated are cotrolled; these estimates may be optimistic i may developig coutries Several authors have, therefore, suggested that large-scale screeig ad treatmet campaigs i developig coutries should take place to improve the poor rates of diagosis ad treatmet. It remais uclear, however, which populatios should be targeted. 12,13 Some authors have suggested that urba dwellers ad higher icome groups are more likely to experiece hypertesio give their risk of processed food cosumptio ad sedetary lifestyles. 14,15 Alteratively, rural ad poor groups may simply be missed by prior surveillace efforts. 7 Similarly, alterative strategies based o sex, isurace status, ad emergig risk factors like obesity have bee suggested To ivestigate the sociodemographic correlates of hypertesio ad its cotrol, we studied the World Health Orgaizatio (WHO) Study o Global Agig ad Adult Health Received March 11, 2013; first decisio March 25, 2013; accepted April 14, From the Prevetio Research Ceter, Ceters for Health Policy, Primary Care, ad Outcomes Research, Ceter o Poverty ad Iequality, Staford Uiversity, Staford, CA (S.B.); Departmet of Public Health ad Policy, Lodo School of Hygiee ad Tropical Medicie, Lodo, Uited Kigdom (S.B.); School of Public Health, Imperial College Lodo, Lodo, Uited Kigdom (C.M.); ad South Asia Network for Chroic Disease, Public Health Foudatio of Idia, New Delhi, Idia (C.M.). The olie-oly Data Supplemet is available with this article at /-/DC1. Correspodece to Sajay Basu, Staford Uiversity School of Medicie, Medical School Office Bldg, X322, 1265 Welch Rd, Mail Code 5411, Staford, CA basus@staford.edu 2013 America Heart Associatio, Ic. Hypertesio is available at DOI: /HYPERTENSIONAHA

2 Basu ad Millett HTN i Middle-Icome Coutries 19 Table 1. Study o Global Agig ad Adult Health Sample s Coutry Sample Size % Media Age (IQR) % Me % Urba BP Data Obtaied HTN Udiagosed Utreated Ucotrolled No. % No. HTNives No. HTNives Chia (39 52) Ghaa (36 51) Idia (30 50) Mexico (31 47) Russia (42 66) South (34 51) Africa Total (35 54) No. HTNives Calculatios used survey samplig weights to compute atioally represetative statistics; hypertesio prevalece rates were age-stadardized agaist a Uited Natios Developmet Programme populatio pyramid. 23 BP idicates blood pressure; HTN, hypertesio; ad IQR, iterquartile rage. (SAGE), which assembled atioally represetative cohorts from 6 coutries udergoig rapid ecoomic developmet (Chia, Ghaa, Idia, Mexico, Russia, ad South Africa). 20 A major advatage of the study was that, as opposed to siglecoutry surveys, the SAGE questioaires ad methods were validated ad applied simultaeously to multiple coutries, ivestigatig what factors may be commo ad geeralizable betwee atios rather tha specific to certai cultures (eg, because of local utritio), uobserved geetic differeces, or healthcare system differeces. 21 Methods We coducted a aalysis of the SAGE data set, icludig participats aged 18 years who were surveyed betwee 2007 ad 2010 (Wave 1, used to study health status ad social/epidemiological risk factors to poor health) from households withi Chia, Ghaa, Idia, Mexico, Russia, ad South Africa. The SAGE clustered household samplig strategy was desiged to geerate atioally represetative Figure. Hypertesio prevalece ad overweight/obesity prevalece by icome quitile amog the World Health Orgaizatio Study o Global Agig ad Adult Health cohort, where quitile 1 is the poorest fifth of the icome distributio i each coutry ad quitile 5 is the wealthiest. Overweight/obese is defied as body mass idex 25 kg/m 2. cohorts. We excluded pregat respodets ad those that did ot have complete blood pressure data or hypertesio diagostic ad treatmet history o iterview. Table 1 describes the demographic make-up ad sample sizes i the study. Blood Pressure Measuremets Blood pressure was measured at home usig a Medistar Wrist Blood Pressure Model S, which avoids the eed for differet cuff sizes as with upper arm sphygmomaometers. This model has bee validated to the Europea Society of Hypertesio stadard ad ISO 9002 stadard. 22 The average of 3 sequetial measuremets of the left wrist was obtaied at home with the arm level to the heart ad the respodet seated ad relaxed, with legs ucrossed. Measuremets were take sequetially, 1 miute apart. All respodets were iterviewed ad asked, Have you ever bee diagosed with high blood pressure (hypertesio)? Those respodig affirmatively were asked whether they had take ay medicatios of treatmet for high blood pressure durig the past 2 weeks ad durig the past 12 moths. Hypertesio was defied as a mea systolic blood pressure 140 mm Hg or diastolic blood pressure 90 mm Hg, or reported diagosis. This defiitio implicitly icludes those treated because treatmet iformatio was asked oly from those respodets who had bee diagosed. Udiagosed hypertesio was defied as those havig hypertesio by examiatio but deyig prior diagosis of hypertesio. Utreated hypertesio was defied as those with hypertesio but deyig medicatios or treatmet for high blood pressure over the past 12 moths. Ucotrolled hypertesio was defied as those with hypertesio whose examiatio did ot have a mea systolic blood pressure <140 mm Hg ad diastolic blood pressure <90 mm Hg. We also looked at the proportio of those diagosed who were treated, ad the proportio of those treated who were cotrolled. Participat s I additio to age ad sex, participats were classified as havig a primary residece that was either urba or rural o the basis of the World Bak stadard defiitios, were classified ito icome quitiles o the basis of their coutry-specific distributio of icome, ad asked about their highest degree of educatio received (primary or less, secodary, or tertiary or more), isurace status (o isurace, isured o a volutary pla, isured o a madatory pla, isured through both a volutary ad madatory pla), umber of healthcare visits i the past year (oce or less, betwee oce i the past year ad oce per moth, or more tha oce per moth), marital status (sigle/divorced/ widowed or married/cohabitatig), tobacco smokig (daily, less tha daily, or oe), curret alcohol use (yes or o), servigs of fruit cosumed per day (0 1, 2 4, or 5), servigs of vegetables cosumed per day (0 1, 2 4, or 5), ad exercise (whether the respodet egaged i moderate-itesity sports, fitess, or recreatioal [leisure] activities that cause a icrease i breathig or heart rate for 10 miutes

3 20 Hypertesio July 2013 Table 2. s Amog Hypertesive Subjects (N=16 170) Sample P Value Ratio (95% CI) Age, y < < [Referece] ( ) ( ) > ( ) Sex Me NA Wome Locatio Urba < [Referece] Rural ( ) Icome Quitile NA Quitile Quitile Quitile Quitile Educatio Primary or less [Referece] Secodary ( ) Tertiary or more ( ) Isurace Madatory < [Referece] Volutary ( ) Both ( ) Noe ( ) Healthcare visits/y Oce/y or less NA >Oce/y to oce/mo >Oce/mo Marital status Sigle/divorced/ [Referece] widowed Married/ ( ) cohabitatig Tobacco smokig Daily < [Referece] Less tha daily ( ) Noe ( ) Curret alcohol use Yes NA No Fruit servigs/d [Referece] ( ) ( ) (cotiued) Table 2. (Cotiued) Sample P Value Ratio (95% CI) Vegetable servigs/d NA BMI, kg/m to < < [Referece] 25 to < ( ) ( ) Waist circumferece, cm < < [Referece] 80 to < ( ) ( ) Hip circumferece, cm < < [Referece] 90 to < ( ) ( ) Exercise No < [Referece] Yes ( ) Probability values are listed from the multiple degrees-of-freedom block test o all categories of the characteristic to assess whether hypertesio rates varied across the categories was calculated from a logistic regressio model with a fixed effect for the characteristic. Adjusted odds ratios are listed from a multivariate logical regressio model with fixed effects for all characteristics with bivariate sigificace at P<0.20. BMI idicates body mass idex; CI, cofidece iterval; ad NA, ot applicable. over the precedig 7 days). Durig the physical examiatio, participats also had their height, weight, hip circumferece, ad waist circumferece measured by traied attedats usig a validated set of istrumets ad approach that has bee detailed elsewhere. Height i meters ad weight i kilograms were used to calculate body mass idex (BMI), which was categorized as uderweight (<18.5 kg/m 2 ), ormal weight (18.5 to <25 kg/m 2 ), overweight (25 to <30 kg/m 2 ), or obese (30 kg/m 2 or above). Statistical Aalyses We used logistic regressio models to assess differeces i rates of hypertesio prevalece, diagosis, treatmet, ad cotrol amog various coutries ad socioecoomic groups withi coutries. We first used a fixed-effects model of the overall SAGE study populatio, icludig dummy variables for coutry to cotrol for uobserved time-ivariat differeces amog coutries (such as differeces i cultural factors leadig to systematic differeces i utritio). We the separately aalyzed sociodemographic correlates to hypertesio prevalece ad cotrol withi each coutry populatio sample. s with a effect of P<0.20 i the uadjusted regressio were the etered, simultaeously, ito a multivariate logistic regressio model to calculate odds ratios (ORs) to assess the 2-sided sigificace of each participat characteristic with a sigificace threshold of P<0.05. Preplaed pairwise comparisos of subgroups (eg, me/wome or urba/rural) were performed i the multivariate model with Farrar Glaubert test for multicolliearity. There were 3367 respodets (7.1%) excluded from the aalysis because of missig data. I all assessmets, survey sample desig weights were used to geerate populatio-represetative estimates of prevalece ad ORs, correctig for differetial probabilities of selectio ad orespose.

4 Basu ad Millett HTN i Middle-Icome Coutries 21 Table 3. s Amog Udiagosed Hypertesive Subjects (N=10 722) Sample P Value Age, y < < [Referece] ( ) ( ) ( ) Sex Me < [Referece] Wome ( ) Locatio Urba < [Referece] Rural ( ) Icome Quitile < [Referece] Quitile ( ) Quitile ( ) Quitile ( ) Quitile ( ) Educatio Primary or less < [Referece] Secodary ( ) Tertiary or more ( ) Isurace Madatory < [Referece] Volutary ( ) Both ( ) Noe ( ) Healthcare visits/y Oce/y or less < [Referece] >Oce/y to ( ) oce/mo >Oce/mo ( ) Marital status Sigle/divorced/ < [Referece] widowed Married/ ( ) cohabitatig Tobacco smokig Daily < [Referece] Less tha daily ( ) Noe ( ) Curret alcohol use Yes < [Referece] No ( ) BMI, kg/m to < < [Referece] 25 to < ( ) ( ) (cotiued) Table 3. (Cotiued) Sample P Value Waist circumferece, cm < < [Referece] 80 to < ( ) ( ) Hip circumferece, cm < < [Referece] 90 to < ( ) ( ) Exercise No NA Yes Probability values are listed from the multiple degrees-of-freedom block test o all categories of the characteristic to assess whether udiagosed hypertesio varied across the categories was calculated from a logistic regressio model with a fixed effect for the characteristic. Adjusted odds ratios are listed from a multivariate logical regressio model with fixed effects for all characteristics with bivariate sigificace at P<0.20. BMI idicates body mass idex; CI, cofidece iterval; ad NA, ot applicable. Prevalece estimates were age-stadardized usig the direct approach usig Uited Natio populatio pyramids for the year 2010, 23 with age clusters chose to esure sufficiet sample size to detect a 10% differece i hypertesio prevalece with >80% power whe applyig a survey desig effect of 2 (POWER software v.3, Natioal Cacer Istitute). Data were aalyzed usig Stata versio 12 (StataCorp). Ethics Approval The SAGE study received huma subjects testig ad ethics coucil approval from research review boards local to each participatig site, ad from the WHO Ethical Review Committee, as detailed elsewhere. 21 Iformed coset was obtaied from each respodet before iterview ad examiatio. Results We examied idividuals for hypertesio (Table 1). Media age at the time of the survey was 44 years (iterquartile rage, 35 54); 49% were me ad 45% lived i urba areas. The age-stadardized hypertesio prevalece rate was lowest for Idia (23%) ad highest for Russia (52%). Amog the 37 the overall sampled populatio who were hypertesive, 66% were udiagosed before the survey, 73% utreated (icludig 16 the diagosed), ad 90% ucotrolled (icludig 70 the treated). The highest probability of beig udiagosed, utreated, or ucotrolled was observed i Ghaa (83 hypertesives udiagosed, 87% utreated, ad 97% ucotrolled); the lowest probability of beig udiagosed ad utreated was i Russia (30% udiagosed ad 35% utreated) ad the lowest probability of beig ucotrolled was i Idia (76% ucotrolled). Prevalece Rates by Participat I bivariate aalyses (Table 2), hypertesio prevalece varied sigificatly (P<0.05) by age (46% higher amog populatios aged >80 versus those <40 years), locatio (5% higher amog urba tha rural populatios), educatio status (7% higher

5 22 Hypertesio July 2013 Table 4. s Amog Utreated Hypertesive Subjects (N=11 747) Sample P Value Age, y < < [Referece] ( ) ( ) ( ) Sex Me < [Referece] Wome ( ) Locatio Urba < [Referece] Rural ( ) Icome Quitile < [Referece] Quitile ( ) Quitile ( ) Quitile ( ) Quitile ( ) Educatio Primary or less < [Referece] Secodary ( ) Tertiary or more ( ) Isurace Madatory < [Referece] Volutary ( ) Both ( ) Noe ( ) Healthcare visits/y Oce/y or less < [Referece] >Oce/y to ( ) oce/mo >Oce/mo ( ) Marital status Sigle/divorced/ < [Referece] widowed Married/ ( ) cohabitatig Tobacco smokig Daily < [Referece] Less tha daily ( ) Noe ( ) Curret alcohol use Yes < [Referece] No ( ) BMI, kg/m to < < [Referece] 25 to < ( ) ( ) (cotiued) Table 4. (Cotiued) Sample P Value Waist circumferece, cm < < [Referece] 80 to < ( ) ( ) Hip circumferece, cm < < [Referece] 90 to < ( ) ( ) Exercise No NA Yes Probability values are listed from the multiple degrees-of-freedom block test o all categories of the characteristic to assess whether utreated hypertesio varied across the categories was calculated from a logistic regressio model with a fixed effect for the characteristic. Adjusted odds ratios are listed from a multivariate logical regressio model with fixed effects for all characteristics with bivariate sigificace at P <0.20. BMI idicates body mass idex; CI, cofidece iterval; ad NA, ot applicable. amog those with oly primary schoolig tha those with secodary or more), isurace status (12% higher amog those with madatory isurace tha those with volutary isurace), tobacco smokig (12% lower amog daily smokers tha osmokers, cosistet with iteratioal studies i which this observatio is thought because of low weight amog chroic smokers), 24 fruit/vegetable cosumptio (4% higher amog those eatig 0 1 servig/d versus those eatig 5 servigs/d of either), ad measures of obesity, icludig BMI, hip circumferece, ad waist circumferece, as well as participatio i physical exercise (14% higher prevalece amog the obese tha ormal weight populatios). All icome groups had high hypertesio prevalece rates (Figure). Prevalece was 33% amog the lowest icome (first) quitile ad the highest icome (fifth) quitile, with the fourth quitile beig highest at 38%. Sex differeces i hypertesio rates were also ot sigificat, with 36 me ad 35 wome havig hypertesio. I pooled multivariate aalysis adjustig for sigificat covariates (Table 2), age remaied a sigificat idepedet predictor of hypertesio prevalece (OR, 5.7; 95% cofidece iterval [CI], ; amog populatios aged >80 versus those <40 years). BMI ad waist circumferece also remaied sigificat (OR, 3.7; 95% CI, for obese versus ormal weight ad OR, 2.1; 95% CI, for those with waist circumferece 90 versus those <80 cm). I aalyses withi each coutry cohort (Table S1 i the olie-oly Data Supplemet), age ad obesity remaied the most cosistet sigificat correlates to hypertesio. Obesity was prevalet i all icome quitiles amog all coutries; i the overall study, 13 the lowest icome quitiles were obese, with obesity prevalece icreasig to 33 the highest icome quitiles. The disaggregated statistics o obesity by icome group i each coutry are listed i the i the olie-oly Data Supplemet. Amog hypertesives, 48% were overweight or obese (Figure).

6 Basu ad Millett HTN i Middle-Icome Coutries 23 s of Udiagosed, Utreated, ad Ucotrolled Populatios I bivariate aalyses, rates of diagosis varied by all variables studied except physical exercise (Table 3). Age, sex, isurace status, ad alcohol use remaied sigificat i the multivariate aalysis. The risk of beig udiagosed fell sigificatly with age (OR, 0.1; 95% CI, amog aged >80 versus those <40 years). Wome were also at sigificatly lower risk tha me of beig udiagosed (OR, 0.4; 95% CI, for wome versus me). Havig volutary isurace coferred a sigificat risk of beig udiagosed tha havig madatory isurace (OR, 4.3; 95% CI, ). I aalyses disaggregated by coutry-specific cohort (Table S2), it was foud that this effect was largely drive by the Chiese cohort, amog whom havig volutary (7 the populatio) rather tha madatory isurace (71 the populatio) was associated with a 10 times greater odds of beig udiagosed for hypertesio (95% CI, ). Beig completely uisured did ot have a idepedetly sigificat effect o the probability of diagosis. The group of volutarily-isured persos was distributed evely amog the icome quitiles, rather tha beig disproportioately poor (i the olie-oly Data Supplemet). Alcohol abstaiers were at a sigificatly lower risk tha drikers of beig udiagosed (OR, 0.6; 95% CI, for odrikers versus drikers). Those who were obese were also at a sigificat lower risk of beig udiagosed, idepedet of icome, though this correlatio may reflect uobserved socioecoomic effects (OR, 0.3; 95% CI, for obese versus ormal weight). Whe aalyzig the determiats of treatmet (Table 4), isurace, age, ad alcohol use remaied major socioecoomic variables associated with treatmet probability i multivariate aalysis of the overall multiatioal study sample, but icome emerged as a major correlate of beig utreated as well. The risk of beig utreated fell sigificatly with age (OR, 0.2; 95% CI, amog aged >80 versus those <40 years), ad with alcohol abstetio (OR, 0.4; 95% CI, amog abstaiers versus drikers). The highest icome quitile had less tha oe third the odds of beig utreated tha the lowest icome quitile (OR, 0.3; 95% CI, of highest icome quitile beig utreated versus lowest icome quitile). Volutary isurace amog the Chiese cohort was observed as icreasig the odds of beig utreated by a factor of 4.6 (95% CI, ) over those with madatory isurace. Whe examiig the determiats of havig ucotrolled hypertesio (Table 5), oly sex emerged as a cosistet sociodemographic idicator of cotrol i multivariate aalyses, with wome havig less tha oe third the risk of beig ucotrolled versus me (OR, 0.3; 95% CI, ). Discussio I this first examiatio of the socioecoomics ad demographics of hypertesio from the WHO SAGE study, we observed that hypertesio prevalece amog adults varied widely but was cosistetly highly prevalet amog middle-icome atios. Although Idia is ofte cosidered a coutry experiecig the highest burde from cardiovascular disease, 25 this may be because of its populatio size as opposed to the actual prevalece of hypertesio, which was lower i Idia (at 23%) tha i Africa coutries for which hypertesio has ot bee extesively discussed previously (Ghaa at 41% prevalece ad South Africa at 50%). Obesity emerged as a strikigly commo correlate to hypertesio, alog with the more traditioally recogized risk factor of icreasig age. Obesity was prevalet eve i the lowest icome quitiles, at >10% prevalece, but did icrease with risig icome, though icome i itself was ot a idepedet predictor of hypertesio. Urba versus rural locatio ad sex were also ot reliable predictors of hypertesio, as all locales ad both sexes experieced very high hypertesio rates. This has importat implicatios for future plaig of health services i rural areas, which are typically uderdeveloped i the coutries studied. Although the commo epidemiological rule of halves suggests that i most locatios, we would expect about half of the hypertesive populatio to be udiagosed, half of those diagosed to be utreated, ad half of those treated to be ucotrolled, 9 a substatially worse profile emerged from the atioally represetative SAGE cohorts. Overall, 66% were udiagosed before the survey, 73% utreated (icludig 16 the diagosed), ad 90% ucotrolled (icludig 70% of the treated). This idicates that the major bottleecks for effective hypertesio cotrol i middle-icome coutries are diagosis ad effective titratio of treatmet, ot ecessarily treatmet iitiatio amog those already diagosed. Hece, further research o screeig ad adherece strategies, as well as quality improvemet at healthcare sites to esure titratio of medicatios, may be critical for improvig outcomes. We foud that the risk of poor diagosis sigificatly reduced with age, ad was sigificatly lower amog wome tha me ad amog alcohol abstaiers tha drikers. Amog predomiatly the Chiese cohort, volutary rather tha madatory isurace icreased the risk of beig udiagosed ad beig utreated. This presets ew data above prior Chiese assessmets that did ot track isurace status. 11 Other key correlates to beig utreated were age (with higher age groups agai beig of lower risk), alcohol abstetio (havig lower risk tha amog drikers), ad icome (reduced risk with higher icome). Oly sex emerged as a cosistet sociodemographic correlate of cotrol, with wome havig less tha oe third the odds of beig ucotrolled versus me. Before discussig how these research results may be used for future hypertesio itervetios, we ote that the study has importat limitatios. First, because the study is observatioal, it caot ifer causality. The associatio betwee obesity ad hypertesio, for example, may reflect broader metabolic sydrome effects i the populatios beig observed. Also, BMI values may have differet cliical implicatios i differet coutries, particularly Asia coutries where covetioal BMI cut-offs may ot be fully predictive of future cardiometabolic outcomes. 26,27 Furthermore, the study used a wrist moitor for blood pressure estimatio, which is more proe to iaccuracy tha brachial moitors. Subjects were also ot screeed for atrial fibrillatio, which ca cause oscilometric measuremet iaccuracies. 28 The reportig of a average of 3 blood pressure measures may be problematic because some people experiece cuff-triggered alertig resposes or white coat reactios. 29 Also, dietary sodium reductio has bee recommeded for middle-icome atios

7 24 Hypertesio July 2013 Table 5. s Amog Ucotrolled Hypertesive Subjects (N=14 495) sample P value ratio (95% CI) Age, y < NA Sex Me < [Referece] Wome ( ) Locatio Urba [Referece] Rural ( ) Icome Quitile [Referece] Quitile ( ) Quitile ( ) Quitile ( ) Quitile ( ) Educatio Primary or less < [Referece] Secodary ( ) Tertiary or more ( ) Isurace Madatory < [Referece] Volutary ( ) Both ( ) Noe ( ) Healthcare visits/y Oce/y or less < [Referece] >Oce/y to ( ) oce/mo >Oce/mo ( ) Marital status Sigle/divorced/ NA widowed Married/ cohabitatig Tobacco smokig Daily NA Less tha daily Noe Curret alcohol use Yes [Referece] No ( ) BMI, kg/m to < [Referece] 25 to < ( ) ( ) (cotiued) Table 5. (Cotiued) Sample P Value Waist circumferece, cm < NA 80 to < Hip circumferece, cm < NA 90 to < Exercise No [Referece] Yes ( ) Probability values are listed from the multiple degrees-of-freedom block test o all categories of the characteristic to assess whether ucotrolled hypertesio varied across the categories was calculated from a logistic regressio model with a fixed effect for the characteristic. Adjusted odds ratios are listed from a multivariate logical regressio model with fixed effects for all characteristics with bivariate sigificace at P<0.20. BMI idicates body mass idex; ad CI, cofidece iterval. just as with high-icome coutries. 25 Dietary assessmet was ot, however, obtaied i SAGE. Aother major limitatio is that metabolic sydrome ad type 2 diabetes mellitus are commoly correlated to hypertesio, the diabetes mellitus data i SAGE are self-reported, which ca bias the data because of differetial accessibility to healthcare. 30,31 Hece, we did ot further stratify the data by diabetes mellitus status. SAGE data also did ot iclude coutries where large populatios abstai from alcohol use (eg, because of religious reasos), ad adopted the World Bak defiitios of urba ad rural, which are limited i how they characterize local areas. Further studies are also eeded to uderstad educatioal ifluece o hypertesio awareess, treatmet, ad cotrol, which was ot comprehesively assessed. The results of the study evertheless cotribute sigificat ew iformatio to the literature. Specifically, whereas previous studies have observed the relatioship betwee obesity ad hypertesio primarily amog high-icome atios or the wealthier idividuals with healthcare access i low-icome settigs, 4,26 these data suggest that the obesity hypertesio relatioship has exteded to all icome quitiles. Furthermore, the SAGE data idetify ew mechaisms by which the problem of low diagostic ad treatmet outcomes may be addressed. Our fidig that volutary versus madatory isurace i Chia was a sigificat correlate to diagosis ad treatmet, eve above uisurace status, has ot bee previously reported to our kowledge ad suggests that further efforts should ivestigate whether a systematic differece i populatios (selectio effect) or i policies (itroducig bias i diagostic ad treatmet probability) could explai this correlatio, which would help to direct future itervetio efforts. Although the INTERHEART ad related studies established that hypertesio was a prevalet risk factor i may developig coutry populatios, 4 such studies were

8 Basu ad Millett HTN i Middle-Icome Coutries 25 ot atioally represetative, ad smaller studies i idividual locales led to the hypothesis that major divides alog urba/ rural, sex, or icome strata may pose the largest differeces i hypertesio rates. We foud that although otable differeces do still exist alog these axes, the prevalece of hypertesio is essetially uiversally high across all these domais, as is the rate of uderdiagosis. Perspectives Overall, the social epidemiology of hypertesio i the studied middle-icome coutries seems closer to high-icome coutries i several ways tha previously hypothesized. Obesity was a sigificat correlate to hypertesio ad was prevalet eve amog the lowest icome quitile (13% obesity), though it was icreasigly prevalet with risig icome. Isurace status ad icome also emerged as sigificat correlates to diagosis ad treatmet probability, respectively, with isurace beig a major cocer amog the Chiese cohort. Sex was the most robust sigificat correlate to the probability of cotrol, idicatig that social factors related to lower cotrol amog me require further ivestigatio to mitigate the impact of hypertesio-related disease amog me i these rapidly developig atios. We foud that the major bottleecks for effective hypertesio cotrol i middle-icome coutries are diagosis ad effective titratio of treatmet, ot ecessarily treatmet iitiatio amog those already diagosed. Ackowledgmets This article uses data from WHO SAGE versio Sources of Fudig Sajay Basu was supported by Staford Uiversity ad the Iteratioal Developmet Research Ceter of Caada. Christopher Millett was fuded by the Higher Educatio Fudig Coucil for Eglad ad the Natioal Istitute for Health Research. SAGE is supported by the Uited States Natioal Istitute o Agig s Divisio of Behavioral ad Social Research through iteragecy agreemets ad research grats (1 R01 AG A1), ad the World Health Orgaizatio s Departmet of Health Statistics ad Iformatio Systems. Noe. Disclosures Refereces 1. Naraya KV, Ali MK, Kopla JP. Global ocommuicable diseases where worlds meet. N Egl J Med ;363: PS Collaboratio. Age-specific relevace of usual blood pressure to vascular mortality: a meta-aalysis of idividual data for oe millio adults i 61 prospective studies. Lacet (Lodo, Eglad). 2002;360: Kearey PM, Whelto M, Reyolds K, Muter P, Whelto PK, He J. Global burde of hypertesio: aalysis of worldwide data. Lacet. 2005;365: Yusuf S, Hawke S, Oupuu S, Das T, Avezum A, Laas F, McQuee M, Budaj A, Pais P, Varigos J, Lisheg L; INTERHEART Study Ivestigators. Effect of potetially modifiable risk factors associated with myocardial ifarctio i 52 coutries (the INTERHEART study): case-cotrol study. Lacet. 2004;364: Lozao R, Naghavi M, Forema K, et al. Global ad regioal mortality from 235 causes of death for 20 age groups i 1990 ad 2010: a systematic aalysis for the Global Burde of Disease Study Lacet. 2012;380: Seligma BJ, Culle MR, Horwitz RI. Agig, trasitio, ad estimatig the global burde of disease. PLoS Oe. 2011;6:e Ezzati M, Vader Hoor S, Lawes CM, Leach R, James WP, Lopez AD, Rodgers A, Murray CJ. Rethikig the diseases of affluece paradigm: global patters of utritioal risks i relatio to ecoomic developmet. PLoS Med. 2005;2:e Deepa R, Shathirai CS, Pradeepa R, Moha V. Is the rule of halves i hypertesio still valid? Evidece from the Cheai Urba Populatio Study. J Assoc Physicias Idia. 2003;51: Joshi Shashak R, Shah Siddharth N. Cotrol of blood pressure i Idia: rule of halves still very much valid. JAPI. 2003;51: Agyemag C. Rural ad urba differeces i blood pressure ad hypertesio i Ghaa, West Africa. Public Health. 2006;120: Gu D, Reyolds K, Wu X, Che J, Dua X, Muter P, Huag G, Reyolds RF, Su S, Whelto PK, He J; IterASIA Collaborative Group. The Iteratioal Collaborative Study of Cardiovascular Disease i ASIA. Prevalece, awareess, treatmet, ad cotrol of hypertesio i chia. Hypertesio. 2002;40: Lim SS, Gaziao TA, Gakidou E, Reddy KS, Farzadfar F, Lozao R, Rodgers A. Prevetio of cardiovascular disease i high-risk idividuals i low-icome ad middle-icome coutries: health effects ad costs. Lacet. 2007;370: Ebrahim S, Pearce N, Smeeth L, Casas JP, Jaffar S, Piot P. Tacklig o-commuicable diseases i low- ad middle-icome coutries: is the evidece from high-icome coutries all we eed? PLoS Med. 2013;10:e Gupta R, Guptha S, Gupta VP, Prakash H. Prevalece ad determiats of hypertesio i the urba populatio of Jaipur i wester Idia. J Hypertes. 1995;13: Gupta R. Meta-aalysis of prevalece of hypertesio i Idia. Idia Heart J. 1997;49: Doll S, Paccaud F, Bovet P, Burier M, Wietlisbach V. Body mass idex, abdomial adiposity ad blood pressure: cosistecy of their associatio across developig ad developed coutries. It J Obes Relat Metab Disord. 2002;26: Reddy KS, Yusuf S. Emergig epidemic of cardiovascular disease i developig coutries. Circulatio. 1998;97: Pretice AM. The emergig epidemic of obesity i developig coutries. It J Epidemiol. 2006;35: Misra A, Khuraa L. Obesity ad the metabolic sydrome i developig coutries. J Cli Edocriol Metab. 2008;93(11 Suppl 1):S Kowal P, Chatterji S, Naidoo N, Biritwum R, Fa W, Lopez Ridaura R, Maximova T, Arokiasamy P, Phaswaa-Mafuya N, Williams S, Sodgrass JJ, Miicuci N, D Este C, Peltzer K, Boerma JT; SAGE Collaborators. Data resource profile: the World Health Orgaizatio Study o global AGEig ad adult health (SAGE). It J Epidemiol. 2012;41: Kowal P, Kah K, Ng N, et al. Ageig ad adult health status i eight lower-icome coutries: the INDEPTH WHO-SAGE collaboratio. Glob Health Actio. 2010;3:. 22. Europea Society of Hypertesio. 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9 26 Hypertesio July Daaei G, Fiucae MM, Lu Y, Sigh GM, Cowa MJ, Paciorek CJ, Li JK, Farzadfar F, Khag YH, Steves GA, Rao M, Ali MK, Riley LM, Robiso CA, Ezzati M. Natioal, regioal, ad global treds i fastig plasma glucose ad diabetes prevalece sice 1980: systematic aalysis of health examiatio surveys ad epidemiological studies with 370 coutryyears ad 2.7 millio participats. Lacet. 2011;378: Novelty ad Sigificace What Is New? May studies of hypertesio have occurred i rapidly developig coutries, but sigle-coutry surveys caot explai what treds i the social epidemiology of hypertesio may be geeralizable across regios, versus specific to idividual locales; we studied hypertesio prevalece estimates from the multicoutry World Health Orgaizatio Study o Global Agig ad Adult Health study to fid commoalities i the social epidemiology of hypertesio amog rapidly developig middle-icome coutries. Sex emerged as a cosistet sociodemographic correlate of cotrol, with wome havig less tha oe third the odds of havig ucotrolled hypertesio versus me i middle-icome atios. Isurace status ad icome also emerged as sigificat correlates to diagosis ad treatmet probability, respectively. Major bottleecks for effective hypertesio cotrol i middle-icome coutries are diagosis ad effective titratio of atihypertesive treatmet, ot ecessarily treatmet iitiatio amog those already diagosed. What Is Relevat? Obesity emerged as a strikigly commo correlate to hypertesio, alog with the more traditioally recogized risk factor of icreasig age i middle-icome coutries. Mass screeig for hypertesio has bee suggested as a hypertesio cotrol strategy for rapidly developig coutries. However, several classical social idicators of ucotrolled hypertesio were ot foud to be robust predictors here. Urba versus rural locatio ad sex were ot reliable predictors of hypertesio, as all locales ad both sexes experieced very high hypertesio rates. Summary More tha 90 hypertesio cases i this sample of middle-icome coutries are ucotrolled, with me havig 3 times the odds as wome of beig ucotrolled. Overall, the social epidemiology of hypertesio i middle-icome coutries seems to be correlated to icreasig obesity prevalece, ad hypertesio cotrol rates are particularly low for adult me across distict cultures.