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# OAR Box 1126 Prepped by Ollie Stewart



## Document

Number: 

# 175)11-1-38 8 Docket Number: 

# A-83-2 2

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Sheet 175 of 182

# Pi-d3-^JZ-2-^lt P. 2 

## v^ Environmental

Health Perspectives Vol. 78, pp. 3-7,1988 

# Epidemiolog y o

f Hypertensio n a s a Publi c Healt h Problem : A n Overvie wa s Backgroun d fo r Evaluatio n o f Bloo d Lead-Bloo d Pressure Relationshi p b y Herma n A . Tyroler

*

A n overvie w o f

th e epidemiolog y o f

bloo dpressur e i s presente da s backgroun dfo r th e Internationa l Symposiu mo f

Bloo dLead-Bloo dPressur e Relationships . Th e correlate s o f bloo dpressur e distribution s i n population s ar e varie dan dnumerous . The y hav e t o b e considere da s eithe r potentia l confounder s o r

modifier s o f

an y bloo dpressure-bloo dlea drelationshi p detected . Th e relatio n o f bloo dpressur e t o cardiovascula r morbidit y an dmortalit y emphasize s th e importanc e o f detectin g an d elucidatin g an y possibl e causa l associatio n o f bloo dlea dwith bloo dpressur e a t lo w levels . Th e tas k o f thi s symposiu mi s o f

publi c healt h importance , a s relativel y mino r change s i n th e distributio n an d mea n level s o

f bloo dpressur e i n population s ar e associate dwit h majo r morbidit y an dmortalit y consequences . 

## Introductio n Thi s symposiu mi s addresse dt o arevie w o f th e evi

denc e tha t

ther e i s arelationshi p betwee n bloo dlea d an dbloo dpressur e levels . W e hav e organize dpresen tation s tha t

permi t discussio n an devaluatio n o f pub

lishe dinvestigation s an dwor k i n progres s relatin g t o bot h huma n an danima l studies . Th e huma n studie s ar e furthe r

stratifie da s clinical , occupationa l epidem

iologic , an dgenera l populatio n epidemiologi c studies . Mos t controvers y i

n thi s fieldha s bee n engendere db y th e genera l populatio n studies , whic h hav e suggeste da causa l relationshi p betwee n increase s in bloo dlea d level s withi n th e rang e o f value s lowe r

tha n thos e considere dclinicall y significan t an dincrease s i n bloo dpressure , als o withi n th e rang e belo w value s considere dclinicall y significan t a s hypertensive . Th e associatio n ha s no t

bee n foun din al l studie s and , whe n present , ha s bee n suc h tha t increas e i n bloo d pressur e wit

h increas e i

n bloo dlea dlevel s ha s bee n o f smal l absolut e magnitud e an dno t constan t acros s age , sex , an drac e subgroups . Despit e th e seemingl y smal l elevation s i

n bloo dpressur e whe n viewe dfro mth e clinica l perspectiv e o

f eac h individual , th e potentia l 'Departmen t

o f Epidemiology , Schoo l o

f Publi c Health , Universit

y o f Nort h Carolina . Chapel Hill , N C 27599 . publi c healt h importanc e o f abloo dlea drelationshi p i s considerabl e du e t o th e stron g associatio n o f bloo d pressur e with cardiovascula r morbidit y an dmor tality , th e leadin g caus e (s ) o f death in ou r

society , an d th e larg e numbe r

o f individual s exposed . Evaluatio n o f th e possibl e contributio n o f bloo dlea dlevel s t o thes e outcome s fro mobservationa l epidemiologi c studie s require s assessmen t

o f whethe r ther e i s evidenc e o

f a n associatio n o

f bloo dlea dwit

h bloo dpressur e levels , it s strength , dose-respons e nature , consistenc y acros s studies , freedo mfro mmeasuremen t biases , an dstatis

tica l independenc e fro mth e effect s o f confoundin g influences . Finally , th e biologi c an dpathophysiologi c plausabilit y o

f th e epidemiologi c observationa l asso ciatio n i s t o b e assesse din ligh t o f th e huma n an d anima l experimenta l studies . A s backgroun dfo

r th e specifi c studie s t o b e reviewe d at th e symposium , i

t wa s deeme dappropriat e t o presen t a n overvie w o

f som e o f th e element s o

f th e epi

demiolog y o

f bloo dpressur e relevan t

t o th e bloo dlead

bloo dpressur e issue . Selectivit y wa s necessar y i n choosin g fro mavas t

literature , a

n epidemiologi c lit

eratur e whos e summarization s themselve s hav e bee n extensiv e (1-4). Th e guidin g principl e i n choosin g materia l wa s t o illuminat e methodologi c an dsub

stantiv e issue s tha t

coul dmisinfor mstudie s o f bloo d pressur e in relatio n t o bloo dlea dlevels . Particula rP. 3
H. A. TYROLER tt
' « attentio n i s calle dt o th e continuou s distributio n o f bloo dpressur e level s i

n populations ; th e larg e numbe r an dvarie dnatur e o

f correlate s o

f bloo dpressure ; th e continuou s natur e o

f th e cardiovascula r

morbidit y an dmortality ris k

function s associate dwit h increas

in g bloo dpressure ; an dth e resultin g larg e potentia l populatio n diseas e burde n o f increase s i

n bloo dpres sure , seemingl y clinicall y insignifican t fo r eac h individual . 

## Distributio n o

f Bloo d Pressure i n Population s Bloo dpressur e i s difficult t o measur e reliabl y in populatio n studies . Ther e i s marke dintraindividua l variability i

n respons e t o th e physica l an dsocial envi

ronmenta l circumstance s o f measuremen t

an d psychologi c response s t o th e measurin g situation . Al

thoug h ther e ar e experiment s suggestin g a n influenc e o f lea do n pressur e responsivity , ther e ar e n o larg e epidemiologi c studie s addressin g thi s issue . Observe r source s o

f measuremen t

variatio n ar e considerabl e an drequir e training , standardization , an dquality contro l assessmen t t o assur e comparability amon g observer s withi n agive n study . Unfortu

nately , objectiv e method s t o assur e measuremen t comparabilit y acros s studies , o r ove r tim e withi n stud y populations , hav e no t

bee n satisfactoril y develope dfo r larg e epidemiologi c studies . Althoug h follow-u p studie s ove r

lon g period s o

f tim e demonstrat e som e trackin g o

f individual s (i.e. , maintenanc e o f ran k positio n base don bloo dpressur e level) , an don e casua l bloo dpressur e leve l i s predictiv e o f morbidit y an d mortality , thes e association s ar e increase db y assess ment s repeate dan daverage dove r time . Thus , ther e ar e methodologi c problem s in evaluatin g populatio n change s i

n bloo dpressur e ove r

time , problem s o

f momen t give n change s i

n bloo dlea dove r

time . Th e resul t

o f al l source s o

f variatio n o

f bloo dpressur e measurement s withi n an damon g individual s i n population s i s acontinuou s distribution , unimoda l in nature , withou t

an y clea r

dividin g point s per mittin g leve l per

se t o distinguis h th e normotensiv e fro mth e categorica l (arbitraril y defined ) hyper

tensive . In th e epidemiologi c domai n th e populatio n i s th e uni t o f study , no t

th e individual , an dpopulation s diffe r i n th e distributio n o

f bloo dpressure . The y diffe r both i n th e mean leve l an di

n th e amoun t

o f variatio n aroun dth e mean . Generally , bu t no t invariably , ther e i s increasin g varianc e an dincreasin g skewnes s toward s highe r

value s wit

h increasin g mea n level s o f bloo dpressure . On compariso n o f tw o population s wit

h differen t mea n levels , th e proportio n o f individual s wit h hig h level s get s progressivel y mor e dissimila r betwee n th e population s a s on e move s furthe r ou t t o highe r value s (arbitraril y categorize da s hyperten

sive ) i n th e tail s o

f th e distributions . Thus , seemingl y smal l difference s i

n mean value s o

f bloo dpressur e o

f population s ca

n b e accompanie dby sizabl e difference s in proportion s o f individuals , with , .elevate d value s or* , alternativel y expressed , sizabl e difference s i n pro- 1

- portion s o

f hypertensives . ? I a.i-.t -v ; ^y,y ... 

## Correlate s o

f Bloo d Pressur e Level s i n Population s Th e know n correlate s o f bloo dpressur e level s i n population s ar e larg e i n number , an dthereb y th e potentia l for

confoundin g o

f abloo dpressur e rela

tionshi p wit

h anothe r

attribute , suc h a s bloo dlea d levels , i s commensuratel y large . In additio n t o th e larg e numbe r

o f correlate s o

f bloo dpressur e level s i

n populations , thei r

operatio n a

t differen t level s o f bio

social organizatio n increase s th e complexity o f assess in g thei r possibl e confoundin g o r effec t modificatio n o f abloo dlead-bloo dpressur e relationship . A brie f consideratio n o

f som e o f thes e correlate s i s organize d b y th e followin g categories : demographic , familial , physica l environment , socia l environment , an d behaviora l factors . 

## Demographi c Correlate s Th e trend s in bloo dpressur e wit h age , amon g th e mos t importan t

factor s i n th e etiolog y o

f hypertension , an dth e associatio n o

f hypertensio n wit

h se x ar e often considere dinvariabl e biologica l effects , minimall y amenabl e t o modification ; however , ag e an dse x ma y b e surrogat e indicator s o f socia l an d physiochemica l environmenta l processes . Fo r example , althoug h mos t population s sho w increase s in mea n bloo dpressur e level s wit

h age , som e d o not . Th e commo n charac

teristic s o f population s withou t

evidenc e o

f increas e i

n bloo dpressur e wit

h ag e hav e variousl y bee n identifie d a s absenc e o

f industrialization , persistenc e o f tradi

tional social structures , an dlow sodiu mingestion . Population s ca

n b e classifie db y th e rat e o f chang e o f bloo dpressur e wit

h ag e an dth e leve l o

f bloo d pressure . A t on e extrem e ar e population s wit h lo w level s o

f bloo d pressur e an dn o increas e o f mean pressur e wit

h age ; a t a n opposit e extrem e ar e population s wit h hig h level s an dmarke dincreas e i

n bloo dpressur e wit

h increas

in g age , e.g. , rura l souther n U.S . blacks . Althoug h linear

increas e i

n pressur e wit

h ag e i s a

n appropriat e approximatio n o f mos t populatio n obser

vation s for

systoli c bloo dpressure , th e cross-sectiona l diastoli c bloo dpressur e dat aar e mor e accuratel y rep resente db y acurvilinea r relationshi p t o age , wit h mea n diastoli c pressur e reachin g aplateau i n middl e ag e an ddecreasin g a

t olde r ages . Th e mean bloo dpres sur e o f differen t age dindividual s in cross-sectiona l survey s ar e singl e point-in-tim e value s for differen t individual s at

differen t achieve dages , an dtherefor e represen t th e composit e effects , i

f any , o f agin g per

se, differen t experience s o

f differen t birt h cohorts , an d selectiv e survival . Prospectiv e studie s in industri

alize dsocietie s confirmth e averag e ris e i n bloo d pressur e (particularl y systolic ) wit h ag e observe dinP. 4
EPIDEMIOLOGY

OFHYPERTENSION cross-sectiona l surveys ; however , no t al l individual s experienc e th e rise , and , amon g thos e wh o do , ther e i s considerabl e variatio n in th e rat e o f rise . Mea n bloo dpressur e level s an dth e prevalenc e o f hypertensio n vary wit

h se x i n amanne r

tha t differ s wit h ag e epochs . Compariso n in industrialize dsocie

tie s o f studie s o f childre n younge r

tha n ag e 1 4 reveal s n o consisten t

se x differences ; in adolescence , youn g adulthood , an dthroug h ag e 4 5 ther e i s unanimit y amon g reporte dstudie s o f highe r mean bloo dpressur e level s in male s an damal e exces s in th e prevalenc e o f hypertension ; across-ove r the n occur s i

n thes e cross sectiona l survey s at

abou t ag e 45 , afte r

whic h mea n bloo dpressur e become s highe r i n wome n tha n i n men . Amon g th e mos t

consisten t

finding s in th e epi

demiolog y o

f hypertensio n i s an exces s i n it s fre

quenc y an ddeleteriou s sequela e i n adul t blac k popu lation s i n th e Unite dStates . Numerou s studie s hav e reporte dashif

t in th e distributio n o

f bloo dpressur e level s i n black s towardhighe r

value s for

both sexe s a

t all adul t ages . Th e ag e at

whic h black s first

manifes t highe r bloo dpressur e tha n white s i s no t clear . Studie s o f teenager s hav e bee n approximatel y equall y divided , wit h som e showin g an d som e no t showin g black

whit e difference s in bloo dpressur e distribution . Althoug h i

t i s no t clea r at what ag e th e black-whit e differenc e i s first

manifest , ther e i s uniformit y amon g studie s in findin g highe r bloo dpressur e level s an da n exces s o f en dorga n sequela e associate dwit h hyper

tensio n fromyoun g adulthoo don , i n survey s o

f black s sample dfro mnationa l prevalenc e survey s an dsur vey s o f loca l communities . Th e highe r bloo dleadlevel s i n black s invite s th e hypothesi s tha t a t leas t som e o f th e shif t towar dhighe r

bloo dpressur e distribution s in black s i s attributabl e to leadexposure . 

## Geneti c an dFamil y Aggregatio n Ther e i s alarg e bod y o f empirica l dat aindicatin g similarit y o

f bloo dpressur e level s withi n families . Briefly summarized , firs t degre e geneti c relative s o f al l age s frominfanc y t o ol dage , studie din divers e socia l an dcultura l settings , ten dt o resembl e on e anothe r i n level s o f systoli c an ddiastoli c bloo dpressure . Th e similarit y o f bloo dpressur e level s o

f relative s doe s no t argu e unequivocall y for

ageneti c cause . In additio n t o sharin g genes , relative s shar e commo n physical , social , an dpsychologica l environments , whic h ca n influenc e bloo dpressure . Aggregatio n o f bloo dpressur e level s amon g nongeneticall y relate dhousehol dmem bers , includin g bu t

no t restricte dt o spous e pairs , ha s bee n reporte di n som e studies . Greate r similarit y woul db e expecte damon g age-contemporaneou s sib

lin g pair s tha n intergenerationa l parent-offsprin g pairs , base do n bot h environmenta l an dgeneti c hy

potheses . Th e empirica l findings ar e i n conflict ; abou t half o f th e reporte dstudie s sho w highe r similarity i

n siblin g pairs . Th e measur e o f similarit y o

f bloo d pressur e amon g geneti c relative s i s greate r tha n tha t observe damon g spouse s o r othe r nongeneti c relate d househol dmembers , in th e instance s wher e th e latte r d o demonstrat e significan t similarit y o

f bloo d pressur e levels . A s measure db y th e correlatio n coef

ficient , thi s i s greate r fo r monozygoti c tha n fo r dizygoti c twins , greate r

for first degre e geneti c rela

tive s tha n spous e pairs , an dgreate r amon g family member s with natura l tha n adopte dchildren . Thes e finding s ar e consisten t with geneti c factor s influ

encin g bloo dpressur e withi n populations . Thes e studie s neithe r

clarif y no r delineat e th e rela

tiv e importanc e o

f geneti c an dfamilia

l environmenta l factors , no r

th e natur e o

f th e geneti c mechanisms . Th e possibility tha t

lea dexert s adifferen t

bloo d pressure elevatin g effect

amon g geneticall y different susceptible s ha s no t bee n empiricall y tested . 

## Socia l an dPhysica l Environmen t Th e sensitivit y o

f bloo dpressur e regulator y mech

anism s t o acut e psychologica l stimul i an dstron g emotiona l reaction s i s marked . Neurohumora l bloo d pressur e an dcardiovascula r contro l i s an integra l componen t

in norma l hemodynamic s an dadaptatio n t o sudde n environmenta l challenges . Therefore , awid e variet y o f interpersona l experiences , externa l situations , emotions , an dperceive dan dexpecte dchange s i n lif e situation s i s associate dwit h acut e elevatio n o

f bloo d pressure . Thes e psychophysiologica l response s ar e part o f th e norma l repertoir e o f responses . Psychosocia l theorie s o

f hypertensio n sugges t

tha t suc h factor s ar e als o involve d in th e etiolog y o f sustaine dhyperten

sion . Neurohumora l relation s t o awid e rang e o f pro cesse s influencin g bloo dpressur e hav e bee n postulated , extendin g fro mth e personalit y basi s o f altere dbloo d pressur e reactivity o

f th e individua l t o th e socia l ori

gin s o f increase dstressors , incorporatin g bot h acquired , learne dmode s o f respons e an d inbor n constitutiona l predisposition . In mos t develope dsocieties , socia l stratification , whethe r indexe db y achieve deducation , occupationa l status , incom e level , o r

acombinatio n o

f thes e mea sures , ha s bee n foun dt o b e inversel y associate dwit h bloo dpressure . Thi s ha s bee n observe d i n th e U.S . fo

r bot h white s an dblacks . Fo r example , amon g th e mor e tha n 150,00 0 individual s screene dfor th e Hyperten

sio n Detectio n an dFollow-U p Program , ther e wa s a stepwis e increas e i n th e prevalenc e o f categoricall y define dhypertensio n with decreasin g educationa l achievemen t

fo r bot h white s an dblacks . Muc h o f th e education-bloo dpressur e associatio n wa s explaine db y a n increas e in th e prevalenc e o f obesit y wit

h decreas

in g education . Th e associatio n o

f bloo dlea dlevel s wit

h social statu s an dth e socia l environment , i.e. , highe r lea dlevel s amon g th e poo r

an damon g thos e residin g in mor e highl y expose drura l an durba n place s o f residence , require s consideratio n o f thes e circumstance s i

n th e stud y o f processe s relatin g bloo dlea dto bloo dpressure . Numerou s element s i n th e food , water , air , an dsoi lP. 5

H. A. TYROLER
o f th e ambien t

physica l environmen t an din th e workplac e ar e relate dt o bloo dpressure . Amon g th e ele

ment s mos t

studie dan dquantitativel y mos t impor

tan t ar e sodium , potassium , calcium , an dmagne sium . Comple x interaction s amon g thes e element s wit h bloo dpressur e an dthei r possibl e role(s ) i

n any lead-bloo dpressur e associatio n requir e systemati c investigations . 

### Behavio r an d Obesit y A sizabl e correlatio n betwee n bloo dpressur e an d indice s o

f bod y weigh t

i n relatio n t o heigh t i n childre n an dadult s ha s repeatedl y bee n demonstrate d i n bot h cross-sectiona l an dlongitudina l population

base dstudies . Th e relationship s ar e continuou s acros s th e rang e o

f bloo dpressur e levels . I n additio n t o measurement s o f th e associatio n betwee n bloo dpressur e an doverweigh t a s continuou s traits , quantitativ e estimate s hav e bee n derive dfro m th e relatio n betwee n baselin e weight , weigh t gain , an d th e incidenc e o

f hypertension , classifie dcategorically . Individua l behavio r

i s astron g determinan t o f bloo dpressur e level s in populations . Th e balanc e o f dietar y calori c intak e an dcalori c expenditur e b y physica l activity i s reflecte din weigh t an dobesity , major correlate s o

f bloo dpressure , an dit s distributio n i n communities . Obesit y per se i s probabl y relate dt o bloo dpressure ; no t

jus t th e amount , bu t

th e bodil y regiona l distributio n o

f fa t appear s t o b e associate d wit h elevate dbloo dpressure . Accumulatio n in th e abdomina l are acontraste dwit h th e extremit y area s seem s t o hav e stronge r

associatio n no t

jus t wit h bloo d pressure , bu t

als o with othe r

cardiovascula r

ris k factors . Dietar y fa

t intake , th e rati o o

f saturate dt o unsaturate dfat , an dth e possibility tha t th e fa t conten t o f marin e animal s influenc e bloo dpressur e level s ar e unde r intensiv e investigatio n a t present . Relation

ship s hav e bee n observe di n population-base dstudie s betwee n th e amoun t

o f alcoho l consumedan daverag e bloo dpressur e levels . Smokin g represent s a n are ao f considerabl e controvers y i n tha t severa l studie s hav e foun da n invers e associatio n betwee n smokin g an d bloo dpressure , bu t

mos t investigator s attribut e tha t t o th e lowe r weigh t o f smokers . Th e incremen t i n weigh t o n cessatio n o

f smokin g i s associate dwit h a n increas e i n bloo dpressure . Th e possibilit y o

f confoundin g o

f th e bloo dlead

bloo dpressur e associatio n b y th e behavioral , dietary , alcoho l consumption , an dsmokin g attribute s dis

cusse drequire s detaile dattentio n an danalysis . 

## Consequence s o

f Bloo d Pressure Level s i n Population s Given th e overvie w presentatio n o f th e distributio n an dantecedents , w e can no w tur n ou r attentio n t o som e o f th e consequence s o

f bloo dpressur e level s i

n populations . Numerou s studie s hav e documente dth e relatio n o f bloo dpressur e t o morbidity an d mortality ; on e i s arecen t

stud y base don th e screenin g o f more , tha n 300,00 0 me n fo

r th e Multipl e Ris k

Facto r Inter

ventio n Tria l an dth e subsequen t 6-yea r follow-u p fo r coronary hear t

diseas e mortality . Bloo d pressure s wer e stratifie dint o age-specifi c quintiles , an dther e gen erall y wa s amonotoni c increas e i n coronar y mortality wit h increasin g level s o

f bloo dpressur e i

n eac h ag e group . Ther e was , however , asuggestio n o f aJ-shape d curv e in th e oldes t

ag e stratum , with th e lowes t quintil e grou p o

f bloo dpressure s havin g slightl y highe r mortality . Althoug h thi s ris k functio n shap e ha s bee n observe di

n th e Framingha mstud y an d othe r studies , thi s i s acontroversia l area ; i n general , th e relationshi p foun di s o f amonotonicall y increas

in g nature . Comparin g th e within-ag e grou p ris k o f mortality o

f thos e i n th e highes t

quintil e t o thos e in th e lowes t

quintil e show s aconsisten t decreas e i

n th e relativ e ris k

wit h increasin g age . I

n contrast , attribut

abl e risk , i.e. , th e arithmeti c differenc e i n th e rate s betwee n thos e i

n th e highes t

an dlowes t

quintile , show s astepwise , consisten t

increas e wit

h increasin g age . Elevate dbloo dpressur e i s aris k facto r no t only for coronar y disease , bu t

als o for mor e specificall y pres sure-relate dcondition s suc h a s congestiv e hear t fail

ur e an dstrokes . Th e relativ e ris k for th e pressure relate dphenomena , particularl y for stroke , i s mark

edl y highe r

tha n fo r coronar y disease : somewha t mor e tha n 2 fo r coronary an d1 0 fo

r stroke . A n estimatio n o

f th e populatio n impac t

i s assesse db y considerin g th e continuou s distributio n o f bloo d pressur e level s i

n populations , th e ris k

functio n o

f stepwis e increase s in diseas e frequenc y wit h increas

in g level s o

f bloo dpressure , an dth e exces s ris k asso ciate dwit h elevate dlevel s abov e arbitraril y chose n cu t points . Mos t

o f th e exces s diseas e i

n population s i s asso ciate dwit

h what clinicall y woul db e considere drela

tivel y mil dt o moderat e elevation s o f bloo dpressure . Althoug h th e relativ e ris k increase s markedl y with progressio n t o highe r

level s o f bloo dpressure , th e prevalenc e i

n th e populatio n o

f individual s wit

h mil d t o moderat e hypertensio n i s proportionatel y greater . Th e ne t effect i s tha t mos t o f th e exces s morbidity an d mortalit y i s associate dwith clinicall y relativel y mino r increase s in th e mid-portio n o f th e rang e o

f distributio n o

f bloo dpressure . Thi s i s a n importan t consideratio n for

thi s symposium . Th e proportio n o f all th e diseas e i

n agive n populatio n associate dwit h elevate dbloo dpressur e i s th e produc t o f th e attributabl e ris k an dth e prevalenc e o

f elevate dpressur e a t

an y chose n leve l an di s calle dth e populatio n attributabl e risk . In th e instanc e o

f mortality , i

f on e divide s th e populatio n attributabl e ris k b y all caus e mortality , th e quotien t i s th e populatio n attributabl e fraction ; namely , th e proportio n o f al l mortalit y i

n th e com munit y associate dwit

h elevate dpressures . A s studie d in on e community-base dstudy , Evan s County , avery hig h proportio n o

f all caus e mortalit y (rangin g fro m approximatel y 18

% for whit e female s t o > 40

% fo r blac k females ) wa s associate dwit h elevate dbloo dpressure .PRSp —' <**Wfl * 5^'ff|?53mrT7?rT:^ 1 , « P. 6
EPIDEMIOLOGY

OF HYPERTENSION 

## Tempora l an d Spatia l Variatio n i n Hypertension-Relate d Mortalit y Major tempora l trend s hav e bee n manifes t for hy

pertension-relate dcause s o f death i n th e Unite dStates . Afte r a n earlie r perio do f rise , coronar y hear t

diseas e mortalit y rate s hav e consistentl y show n a n approx imatel y 2 % declin e pe r

year sinc e mid-1960 . Ther e ha s bee n mor e tha n a40

% declin e in coronar y mortality i n th e las t 20 years , reflecte di

n all cardiovascular

diseas e an din all-caus e mortalit y rat e declines . Th e declin e starte dearlie r

an dha s bee n eve n greate r for strok e mortality . In fact , strok e mortalit y starte ddeclinin g lon g befor e effectiv e antihypertensiv e therap y wa s developed , s o th e determinant s o f declinin g strok e mortalit y clearl y includ e factor s othe r tha n medica l treatment . However , sinc e abou t 1972-73 , coincidenta l wit h th e initiatio n o

f aNationa l Hig h Bloo dPressur e Educatio n Progra mi

n th e U.S. , ther e ha s bee n a n acceleratio n o

f th e declin e i

n strok e mortality . Man y o f th e studie s reviewe dat thi s symposiu m hav e bee n performe ddurin g aperio do f sharpl y de

creasin g cardiovascula r mortality . Ther e als o i s marke dgeographi c variatio n i n th e Unite dState s in strok e mortality . Mos t

o f th e hig h rat e area s ar e i n th e easter n portio n o

f th e Unite dStates ; particularly , th e southeaster n portion , an dmos t o f th e lo w rat e area s ar e i n th e wester n portion . Th e geographi c pattern , al

thoug h decreasing , ha s persiste dove r th e pas t 20 to 2 5 years , despit e th e marke ddeclin e i n th e leve l o

f mor tality . Therefore , i

t i s importan t

t o conside r

th e pos sibility tha t

ther e i s geographi c variatio n in bloo d pressur e distribution s an dt o accoun t for thi s pos sibility i

n analyse s o

f association s o

f bloo dpressur e with bloo dlea dusin g dat aderive dfro mnationa l samples . 

## Conclusion s I n summary , then , thi s pape r ha s presente d a

n overvie w o

f th e correlates , antecedents , an ddeter

minants , whic h ar e extremel y varie din kin dan d numerou s i

n amount , o

f bloo dpressur e distribution s i n populations . Thes e factor s hav e t o b e considere da s eithe r potentia l confounders o r modifier s o

f any bloo d pressure-bloo dlea drelationshi p detected . Th e relatio n o f bloo dpressur e t o cardiovascula r morbidit y an d mortality emphasize s th e importanc e o f detectin g an d elucidatin g any possibl e causa l associatio n o f bloo d lea dwit h bloo dpressur e a

t low levels . Th e tas k

o f thi s symposiu mi s o

f publi c healt h importance , a s rela

tivel y mino r

change s in th e distributio n an dmea n level s o f bloo dpressur e in population s ar e associate d wit h majo r morbidity an dmortality consequences .

REFERENCE S 1 . Stamler , J. , Stamler , R , andPullman , T . N. , Eds . Th e Epidemiolog y o f Hypertension . Grun e andStratton , Ne w York , 1967 . 2 . Paul , 0. , Ed . Epidemiolog y an dContro l o f Hypertension . Intercontinental Medica

l Boo k Corporation , Ne

w York , 1975 . 3 . Bulpitt , C . J. , Ed . Epidemiolog y o f Hypertension . In : Handboo k o f Hypertension , Vol . 6 (W . H . Bukenhage r an dJ . L . Reid , Eds.) , Elsevier , Amsterdam , 1985 . 4 . Tyroler , H . A . Hypertension . In : Publi c Healt h an dPreventiv e Medicin e (Joh n M . Last , Ed.) , Appleton-Century-Crofts , Eas t Nonvalk , CT , 1986 .P. 7 •a*fflS££Kr asssrr^ . "!%&: sssava 

# SYMPOSIU M O N LEAD-BLOO D PRESSUR E RELATIONSHIP S

Apri l 27-29,198 7 Chape l Hill , Nort h Carolin a Sponsore d by : Universit y o f Nort h Carolin a a

t Chape l Hil l Internationa l Lea d Zin c Researc h Organization , Inc . U.S . Environmenta l Protectio n Agency America n Hear

t Associatio n

Editor : W . Victer yP. 8

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