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The blood pressure of Chinese living in Eastern Canada
A
STI’DY 01’ hluod pressure in groups of people ol’ differcut races and nationalities is of importance in setting standards of normal averages among them. It also serves to reveal the incidence of hppertension as .well as the influence of sitch factors as environment7 mode OF living attd hercc1it.y OTT the height ot’ systc,lic* and diastolic blood pressure. ,\rterial }i~l)ertelision-so common in civilized countries, partiCL?larly
ill
the
tPnl[E!~~~te
zone-k
OI’
quite
iUfn?ClUellt
OCTUIT’ellee
ill
C’ruickshank,’ liilhorn,” Foster” 1. It is generally ( ‘hina ((‘adbury,’ recognized, too, that the blood ~~rwsuw of (‘hinese living in (‘hina is at a lower level than thtb aweptcd stan(l;lrds for Americans and IXuropeans. Relwrts in the litcraturc show that this is true for different sections ol that densely populatecl country.
( Gldlnlryv’ found in il series 01’ healthy (‘antonese (South Llhina) students that the systolic pressure ilverages 20-30 mm. Hg less and the diastolic lo-20 mm. lower than the standards for European and American men oE correspondin, 0’ age, weight ;rn(l height. The analysis of the records of natives living in Northcrt~ (‘him1 IJJ- Tung.” showed a mean systolic of 102 mm. for the ages fiftrcu to nineteen years, and I13 mm. for fift.y to fifty-four years, vith il c.oi,rcs],onding rise in the diastolic from 64 tu ‘7:3 for the same age lberiods. Kilborn’~ examined 700 Szechwanesc (West. (‘kina ) students and ohtaiucd a mean systolic presSLII’C of 111 mm. and diastolic of 70 mm. Similarly, Ying:” in a report (l&st, (lent,ral C’hina) obtained of a smaller group living in (‘hekiang :tverilge figures of 110-I 18 with a rise above 12.5 mm. for group over fifty years of age. In contrast to these studies are the observations of ,Ylvarez,7 who it) 6,000 healthy American mtw ranging in age from sisteen to forty years found it11 aver;lg~ q-stolic l,lood pressure of 129 mm. It is ge~~erally accepted tl>ilt the ~JIY’SSLWC ~1’ n0rma1 adu1t.s of Anglo Saxon origiu is ahout I%-1% mm. illId diastolic 80-85 mm. ( Symonds,8 Woley”) . alth~~ugh somewhat higher readings are still considered normal. Thus l-Imntc~ id Frost ‘s”’ statistics show that the average normal systolic pressure \-aries from I20 to 1% and diastolic from 80 to 89 for the ages twent.y to sixty years. In c(jntr;rsting h~ood pressures of Chinese
and Americans, t,he evidence therefore seems to show that the former’s level / is consistently about IO-15 mm. lower than that of the latter. Another interesting fact is revealed in the influence of environment on the height of hloo,d pressure. ‘I’~tng~~rworded the pressure of 30 C’hinesc students in America ant1 again in Peking three years later. An average drop of I1 mm, in systolic and X mm. in diastolic was noted after thcii return to C%ina. In 58 ,imericans studied in the sameway, this author” showed that a distinct decrease in blood pressure occurs in Westcruers residing in C’hina. Foster+ came to the same c~onclusion.for in a groulj of 120 Americans living in Hullan, hc found that the average pressure ;lpplVa.CIlCd thi>t 01’ the IoWl C‘11inesr ion. \Vith these olservations in mind, it seemedof int.ercst to illVCStigiltc ;I group) of ( ‘hiiwe living in Canada in order to determine their average blood pressure. Snch a study would also indicate the frequency of arterial hypertension among them. fNP~)Lllil,t
PROCEDURE
Two hundred and thirty-nine C%ineselivin, 1).in the city of Nontrcal, whose ages range from seven to sixty-nine years (Table I) form the basis of this report. Only 4 females are included because of the small number of Chinese women in the local colony. Practically all Chinese in this community came originally from C’anton and the immediate neighborhood in the south of (‘hina. The majority have lived here for many years with only occasional brief visits to China. Many of them Their have become thoronghl,v acclimatixetl to our Western civilization. ocruyat.ions (Table II j are for the most part manual labor ill larmdrg or kitchen. TABLE
Most
I
of the blood pressure records were taken during the week-ends,
when the CIhinesc assemblefor diversion and amusement. All readings were done by the author and in the mid-afternoon or early evening. A standard mercury sph~.gmomanorneterwas used with a 12 cm. cuff. The beginning 01’ the first and fourth phases was regarded as systolic and diastolic pressure respectively. The subjects sat comfortably in a chair, resting one arm on an adjoinin g table. With a few exceptions, they had not worked immediately before the recording of the pressure. The Chinese are rather phlegmatic and ON that account did not manifest un-
these measurements. When the first blood pressure reading was found to be 140 mm. (systolic*) or over, the subject was instructed to rest cluietly while sitting in the chair and the reading repeated after five minutes. The blood pressure was checked in these instances because ot the well-known tendency of nervousness and cscitement. to cause a rise III several instances three consecutive readings in systolic pressure. were made in the same subjert. In a number of normal individuals, and particularly in those with hypertension. the heart was esamined for evidcnce of valvnlar disease and enlargement. Thtb pulse rate and 1mesencc or absence of peripheral arteriosclerosis w~rc noted as frequently as lwssihle. OHSER%-PlTlO?;S
Blood I’Y( SSL~ JY wed D,rc ~*~tiw~ of K(,sidc IIC(’ in CJc~~drr .-The majority of’ the Cm’hinesein Montreal have been living here for ten years or longer ; iherefore one (*ittrtlot correlate the height of the bloocl pressure with the length of time they have been residing here. Thus only 4 subjects have been in this country less thalt five years, and 8 between six and nine \-ears. Ninetyone have been residents of (‘anada for from ten to nineteen years itnd 116 have been here for more t.han twenty years. The average for all cases, escludin, 0 those born in CGumda, is nineteen and one-half years. It may be mentioned, however, that the more recent immigrants do show a distinct tendenrp toward hypotension. Thus a male, aged forty-three years, in ( ‘;~nada three years, has a blood pressure
of 78/S: another, aged thirty-six years, in Canada four years, has a hloood pressure of 102,/66; and a third, a young Chinese physician aged twent.y-five years, in (‘anada ills0 for fol1r years, Was observed to have il pressure of 104/8-l.
111 24 10 $1
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1S 14 IS Ii ?A 14
1iO.L.l 1 cj’,.-. i
1.5”.-1 . Average Awrap
systolic dinstolic
= =
Blood P~YJ.Y.SUWin C!n,ltrdicr71-BOt.11.Chi?l~.sc,.--T\~ellt?- individuals arc included in this category, alltl Table III shows the relation 01 their blood pressure to height and weight. All have normal pressures, and when averaged the syst,olic ecluals 11’7.1 mm. and the diastolic 81.0 mm. Whell we compare these figures with those reported in native Chinese of similar age periods, we find that the ( ‘anadian subjects hare definitely higher systolic and cliastolir pressures. The arer;gc blood pressure in this latter group is lower than that obtained for the series of 239 cases,but the two arc not coml)arable~because the C’anadian-born suhjeck number only 20 in all and are predominantly in the younger age Ijeriods of lil:c. 2’11~il~*c~:~~y~~ Blood I~w.s.ww fit* Di#cw?rt LIcJc~.s.--Acomparison of the mean or average blood presswe obtained in our group with that reported hy Thing” for similar itge ljeriods is shown in Tahle IT. It is obvious that the average systolic 1)rcssnre of Chinese living in Fanada is distinet.ly higher (by abont 10 mm. ) J’or each decade than that I’oi 1li~tiWS lirin$ in China, especially in youn,v C 11~1middle-aged adults. In 1KJth a slight, hut steady increase in pressure occurs with advancing age and in the later decades (fifty to sixty-nine years) there is a sharp dsc which illlTl0St~ reilcht?s 1-M mm. In our subjects this may he iivconntetl for by the greater frequency of hypcrten,4on in the older melt.
400
Thus for the ages fifty to sixty-nine years, 21 subjects had systolic pressures above 140 mm., whereas in the earlier decades there were onlr 14 above this level. This is even more striking when we bear in mind the fact that the 31 cases with hypertension o~~ux!d in a total of 66 sllbjccts while the 14 yuui~gcr hypertcnsivcs were found in 173 subjects. The average pressure in Canadian Chinese is in fact the same as that I’or (hl~aw;s,~ white proplc 01 similar ages! living on this cont,inent Symonds,s Woley”) . The same conclusions hold true for the nvcra~es of diastolic pressure, though there is not such a significant, rise with ilcl~allcing age. Table 11’ shows that the average diastolic pressures of (.‘anadian Chinese arc higher than those of ihcir cwnl)atriots residing in C’hinn. RELATION
OF SYSTOLIC
BLOOD
PRESSURE
PRESSURE IN MM.
AGE
5-9
70. 79 so- 89 90. 99
100-109 110-119 120-129 130-139 140-149 150-159 160-169 170-179 180-189 190-199 ?cw209 210-219 -
Total
TO AGE IX 239 CHINESE IN
30-39
I
YEARS
411-.&!I -1 1 0
s
10 13 35 I ,s 3 1 ::
13
3
13 12 2 2
50-59 1 1 8 11 16 G 1
3 3
1
2
1
/
3
,
--t( I 31
I
50
--
Sl
-.
1 1
Relntio~~ of f$ytolic and Dia,stolic Blood Pt~cssu~~cto dc~e.-The levels of systolic and diastolic blood pressure :for each decade are shown in (185 or 77.1 Tables V and VI respectively. The majority of OUL ciIs('s per cent) a.re in the age, group between thirty and fifty-nine yrars. One hundred and seventy-four subjects (72.8 per cent,) hare systolic blood pressures ranging between 110 and 139 mm., whereas in 35 (l-L.6 per cent) the reading is above 140 mm. The largest, single group 01’ 71 casesoccurs in the 120-129 mm. division. It is seen how few C~SCS actually have pressures below 110 mm., thus esl~laining the higher mean pressure of Western Chinese as compared to those living in China. In the distribution of the diastolic records, 166 subjects (70.0 per cult) have rea.dings below 90 mm., of which 76 have a pressure of 80-89 mm. In 20 (8.4 l)er cent) a pathological readin,(7 of over 100 mm. was foui~~l. Here, too, really low f$~res arc rclativcxly u~~t'tmnw~~ ill 111~ cli;tstcd it+ pressures 01: Canadian Chinese.
402
THE
AMERICAN
HEART TABLE
*In shortly
2 subjects after the
diastolic onset of
the
pressure first
could (systolic)
JOURNAI.
VI
not
be phase.
recorded.
the
sound
disapw%wing
Uloo,d PWSSWC axl @b&g.-In a study of this kind, it is difficult to define precisely where obesitv begins. It is generally agreed, however, that an excess 01 2.5 per cent or more above the (MeLester, I3 Harrop14) standard or ideal weight, -for age and height, is to be considered abnormal. But many persons are found who are 20 pounds (9.0 kilos) or more above their ideal weight, and these I:all into the overweight class. Of our 239 Chinese, 11 were observed to b11 distinctly obese, and 12 were included in the second group of overweight individuals, giving a total Tn common wit,h white peaof 23 or 10 per cent in the obesity group. pie, the lat.er decades are subject. to ohesit.y ; thus 1 of the obese Chinese were in the fourth decade of life, 3 in the fifth and 9 in the sixth decade. When we come to examine the blood pressures of these, we find that, 5 obese subjects have art,erial hypertension ; i.e., a systolic blood pressure above 140 mm., and 6 have diast,olic pressures over 100 mm. There is therefore in this small group of overweight, C’hinese a higher incidence of hypertension (21.7 per cent) than in those o.l: normal or a,verage weight (10.1 per cent). This is in agreement with what, is generall! found, viz., that. high blood pressures occur with greater frequency in those who are obese than in those who are not. (Alvarez and Stanley,’ Symonds,s Hartman and Ghristlj) . It should be added that the diet of Canadian Chinese is ;I, liberal one and moderately well halancrcl. 111 Chins the natives subsist, largely on a vegetable diet. Hypertemiolz ilb Chinese.-A systolic pressure of 140 mm. Hg is usually regarded with suspicion at, any age, and in the present study 2 consecutive readings above this level are held to he pathological and the cases included in the hypertensive gtvnp. There were 27 subjects (11.2 per cent) with such elevated pressures. It is quite possible that a number of these ought not to be considered hypertensive in view of the well-known effect of nervousness and apprehension in producing a rise of systolic pressure. And though most 01’ the Chinese did not mani-
KEAKOWEIZ
:
KLOOD
PRESSURE
OJT CHINESE
IN
CANADA
403
fest any uneasiness, yet the procedure of taking blood pressure was a strange one to many. As mentioned before, 8 five-minute rest interval was allowed between the first, >md second reading to remove as much ol’ the IICI’VIJIIS factor 21s possible. ,I iiumher had undoubted hypertension with the systolic, just below or ill)OVe 200 mm., and in 12 Sub111 14 cases the heart was esjects the tliiIStOlic* \vilS o\‘El’ 100 111111. and in 6 o I) thcisc thcrc was contirmatory evidence of il mined, hypertensive disease mnnifest,ed hy cardiac enlargement and aecentuetion of the second aorfic sound at the base. In one subject. there was ;t. mitra1 insufficient\witI enlarged heart and ill another pronounce<{ peripheral arteriosclerosis. In 7 no evitlence of organic or valvular heart, disease could be rliceitcd by ordinaq- physical examination. The heart WNS also examined in 2% subjects whose blood pressures were within normal limits, and in 2 cdases rheumatic Avular heart disease \VilS detected. The IV?ITlili~ltl~~ were healthy. The frequency ol’ hypertension in C’hinese living in Canada is certainly ill marked contrast to its rarity in (‘hinese natives. FosteP states that among 4,000 C’hinese admissions to the medical service of the NllIl~lll-Jyillf? HOSpitill in C‘hina, he wits able to find less than 20 with a blood pressure ol’ 160 or over. In his private practice in New Englancl. however, 16 per cacnt of his office patients had pressures of 150 mm. or over. The etiology oC arterial hyl)crtcnsion remains obscure and several factors have been mentioned as contributory agents. Thus constitution, endocrine gland chan~cs, diet, climate and mode of living have all been suggested as causes. Of these environment and mode of living deserve attention. In China, the tempo of life is certainly at a slower pace, and nervous straill, so &x&erist.ic of Western civilizais rare among the natives, and tion, is relatively absent. Hypertension even white people after n short residence are found to have lowered hlood pressures. On the other hand, when the Chinese emigrate to this country, their blood pressures increase so that their average pressure is the same as that of the white inhabitants and hypertension is found frequently enough.
This work was undertaken to determine t,he blood pressure of Chinese living in Clanada for a number of years and to compare theil average pressure with that of the white inhabitants. The great majority of the subjects have been in Canada for ten years or more, and their average blood pressure is 10 mm. or more higher than that of Chinese natives for each de~adc. As a matter of fact, their pressures are equal to those reported for native West,crriers. The ast,onishing finding of hypertension in 11 per cent of our subjects compared to its rarity in China, suggests the importance of the -Ale of worry and
404
THE
AMERICAN
HEART
JOVRNAI;
nervous strain of western life, as well as dietary and other environmental fa.ctors, in the etiology o-f high blood pressure. In a small number of Canadian-born Chincsc the avwuge 1)rrssure was observed to be well above that reported for Chinese natives of similar age lwriods, ;igain eml)hasizing cnvironmcnt a~ :I in influencing blood I)ressun’. Ubesity oc!cuIwd it1 10 I)cr cwlt of the sul),jects. illld in I hesc h~pertensioii was not uncommon. 01’ lhc 39 iudividuals in whom the heart was examined, 6 were found to have hyl)ertensive heart discilsc ilnd 2 rheumat~ic valvular disease. fitdO
SUMMARY
AND
CONCI~OSIOKS
The average blood pressure of Chinese living in Canada for ten years or more is consistently higher (10 mm. Hg) than that reported for Chinese natives. Canadian Chinese have pressures the same as those of the white population. In this series hypert,ension occurs with SWprising frequency (11.2 per cent), in contrast, to its rarity in China. RIWFRI’NWS .,I
1
1. Cadbury, W. W.: The Blood Pressure of I;ormaI Cantonew Students, .irch. Int. Med. 30: 362 1922. 2. Cruickshank, E. W. iJ.: Physiological standards in North China, China N. J. 37: 1, 1923. 3. Kilborn, L. G.: l3lood Prcssnrc of Pzccl~wanese Students, c%ina M. J. 40: 1, 1926. Arch. tnt. Med. 40: 4. Foster, J. H.: Blood l’rcssurc of E’orcignrra in (‘hina, 35, 1937. ;5. Tung, C. L.: Blood Pressure of Northern Chinese Males, Chinese J. Physiol. 4: 117, 1930. G. Ying, Y. I’.: Blood Prcsxure of Healthy Tndividoals in Shaohing, (‘hina 11. .l. 40: 641, 1926. 7. Alvarez, TV. C., and Stanley, L. L.: Blood Pressure in G~lilO Prisoners and 400 Prison Guards, Arch. Int. Ned. 46: 17, 1930. of Healthy Men and Women, J. A. 31. A. s. Symends, B. : The Blood Pressure 80:
232,
1923.
9* . Woley, H. I’.: The Kormal Yariution of the Systolic Blood Pressure, .T. A. M. A. 55: 121, 1910. 10. Frost, IT. &I.: IIypertension and Longevity, Boston 11. 8~ 6. J. 193: 241, 19%. 11. Tung, C’. L.: The Blood Pressure of Chinese in China and in the U. S. A., Chinese J. Phyeiol. rep. ser. 1: 93, 1925. Hypotension of Foreigners in China, Arc.h. Int. Med. 40: I?. Idem : The Relative 1.53, 1937. J. S.: Sutrition xnd Diet in Health and Disease, Philadelphia, 13. MeLester, ea. 2, 1941,W. H. S;aunders & Co. Dirt in TXscasc, T%lxdelphia, 1930, P. Blakiston’s Son 14. Harrop, G. A., *Jr.: & co. Blood Pressure and Weight, Arch. tnt. 7.5. Hartman, 11. R., and (Christ. 1). 11.: Mea.
44:
16. Foster, J. Il.: Observations
877,
1929.
The Practice en Hylwrtensiou,
of
X
China and New England J. Med. 203: 1073, 1930.
With
STI’DY 01’ hluod pressure in groups of people ol’ differcut races and nationalities is of importance in setting standards of normal averages among them. It also serves to reveal the incidence of hppertension as .well as the influence of sitch factors as environment7 mode OF living attd hercc1it.y OTT the height ot’ systc,lic* and diastolic blood pressure. ,\rterial }i~l)ertelision-so common in civilized countries, partiCL?larly
ill
the
tPnl[E!~~~te
zone-k
OI’
quite
iUfn?ClUellt
OCTUIT’ellee
ill
C’ruickshank,’ liilhorn,” Foster” 1. It is generally ( ‘hina ((‘adbury,’ recognized, too, that the blood ~~rwsuw of (‘hinese living in (‘hina is at a lower level than thtb aweptcd stan(l;lrds for Americans and IXuropeans. Relwrts in the litcraturc show that this is true for different sections ol that densely populatecl country.
( Gldlnlryv’ found in il series 01’ healthy (‘antonese (South Llhina) students that the systolic pressure ilverages 20-30 mm. Hg less and the diastolic lo-20 mm. lower than the standards for European and American men oE correspondin, 0’ age, weight ;rn(l height. The analysis of the records of natives living in Northcrt~ (‘him1 IJJ- Tung.” showed a mean systolic of 102 mm. for the ages fiftrcu to nineteen years, and I13 mm. for fift.y to fifty-four years, vith il c.oi,rcs],onding rise in the diastolic from 64 tu ‘7:3 for the same age lberiods. Kilborn’~ examined 700 Szechwanesc (West. (‘kina ) students and ohtaiucd a mean systolic presSLII’C of 111 mm. and diastolic of 70 mm. Similarly, Ying:” in a report (l&st, (lent,ral C’hina) obtained of a smaller group living in (‘hekiang :tverilge figures of 110-I 18 with a rise above 12.5 mm. for group over fifty years of age. In contrast to these studies are the observations of ,Ylvarez,7 who it) 6,000 healthy American mtw ranging in age from sisteen to forty years found it11 aver;lg~ q-stolic l,lood pressure of 129 mm. It is ge~~erally accepted tl>ilt the ~JIY’SSLWC ~1’ n0rma1 adu1t.s of Anglo Saxon origiu is ahout I%-1% mm. illId diastolic 80-85 mm. ( Symonds,8 Woley”) . alth~~ugh somewhat higher readings are still considered normal. Thus l-Imntc~ id Frost ‘s”’ statistics show that the average normal systolic pressure \-aries from I20 to 1% and diastolic from 80 to 89 for the ages twent.y to sixty years. In c(jntr;rsting h~ood pressures of Chinese
and Americans, t,he evidence therefore seems to show that the former’s level / is consistently about IO-15 mm. lower than that of the latter. Another interesting fact is revealed in the influence of environment on the height of hloo,d pressure. ‘I’~tng~~rworded the pressure of 30 C’hinesc students in America ant1 again in Peking three years later. An average drop of I1 mm, in systolic and X mm. in diastolic was noted after thcii return to C%ina. In 58 ,imericans studied in the sameway, this author” showed that a distinct decrease in blood pressure occurs in Westcruers residing in C’hina. Foster+ came to the same c~onclusion.for in a groulj of 120 Americans living in Hullan, hc found that the average pressure ;lpplVa.CIlCd thi>t 01’ the IoWl C‘11inesr ion. \Vith these olservations in mind, it seemedof int.ercst to illVCStigiltc ;I group) of ( ‘hiiwe living in Canada in order to determine their average blood pressure. Snch a study would also indicate the frequency of arterial hypertension among them. fNP~)Lllil,t
PROCEDURE
Two hundred and thirty-nine C%ineselivin, 1).in the city of Nontrcal, whose ages range from seven to sixty-nine years (Table I) form the basis of this report. Only 4 females are included because of the small number of Chinese women in the local colony. Practically all Chinese in this community came originally from C’anton and the immediate neighborhood in the south of (‘hina. The majority have lived here for many years with only occasional brief visits to China. Many of them Their have become thoronghl,v acclimatixetl to our Western civilization. ocruyat.ions (Table II j are for the most part manual labor ill larmdrg or kitchen. TABLE
Most
I
of the blood pressure records were taken during the week-ends,
when the CIhinesc assemblefor diversion and amusement. All readings were done by the author and in the mid-afternoon or early evening. A standard mercury sph~.gmomanorneterwas used with a 12 cm. cuff. The beginning 01’ the first and fourth phases was regarded as systolic and diastolic pressure respectively. The subjects sat comfortably in a chair, resting one arm on an adjoinin g table. With a few exceptions, they had not worked immediately before the recording of the pressure. The Chinese are rather phlegmatic and ON that account did not manifest un-
these measurements. When the first blood pressure reading was found to be 140 mm. (systolic*) or over, the subject was instructed to rest cluietly while sitting in the chair and the reading repeated after five minutes. The blood pressure was checked in these instances because ot the well-known tendency of nervousness and cscitement. to cause a rise III several instances three consecutive readings in systolic pressure. were made in the same subjert. In a number of normal individuals, and particularly in those with hypertension. the heart was esamined for evidcnce of valvnlar disease and enlargement. Thtb pulse rate and 1mesencc or absence of peripheral arteriosclerosis w~rc noted as frequently as lwssihle. OHSER%-PlTlO?;S
Blood I’Y( SSL~ JY wed D,rc ~*~tiw~ of K(,sidc IIC(’ in CJc~~drr .-The majority of’ the Cm’hinesein Montreal have been living here for ten years or longer ; iherefore one (*ittrtlot correlate the height of the bloocl pressure with the length of time they have been residing here. Thus only 4 subjects have been in this country less thalt five years, and 8 between six and nine \-ears. Ninetyone have been residents of (‘anada for from ten to nineteen years itnd 116 have been here for more t.han twenty years. The average for all cases, escludin, 0 those born in CGumda, is nineteen and one-half years. It may be mentioned, however, that the more recent immigrants do show a distinct tendenrp toward hypotension. Thus a male, aged forty-three years, in ( ‘;~nada three years, has a blood pressure
of 78/S: another, aged thirty-six years, in Canada four years, has a hloood pressure of 102,/66; and a third, a young Chinese physician aged twent.y-five years, in (‘anada ills0 for fol1r years, Was observed to have il pressure of 104/8-l.
111 24 10 $1
i4..7 .i!l.:!
16i.i 1tii.i
: : : :
ici SII s4 i-l
: : : : : :
TS iS (ili i4 !I1 i!l
li.i.3 1Gi.l 17ll.L’ 1 i52.4 lGC..i
2:: “ ,s
1S 14 IS Ii ?A 14
1iO.L.l 1 cj’,.-. i
1.5”.-1 . Average Awrap
systolic dinstolic
= =
Blood P~YJ.Y.SUWin C!n,ltrdicr71-BOt.11.Chi?l~.sc,.--T\~ellt?- individuals arc included in this category, alltl Table III shows the relation 01 their blood pressure to height and weight. All have normal pressures, and when averaged the syst,olic ecluals 11’7.1 mm. and the diastolic 81.0 mm. Whell we compare these figures with those reported in native Chinese of similar age periods, we find that the ( ‘anadian subjects hare definitely higher systolic and cliastolir pressures. The arer;gc blood pressure in this latter group is lower than that obtained for the series of 239 cases,but the two arc not coml)arable~because the C’anadian-born suhjeck number only 20 in all and are predominantly in the younger age Ijeriods of lil:c. 2’11~il~*c~:~~y~~ Blood I~w.s.ww fit* Di#cw?rt LIcJc~.s.--Acomparison of the mean or average blood presswe obtained in our group with that reported hy Thing” for similar itge ljeriods is shown in Tahle IT. It is obvious that the average systolic 1)rcssnre of Chinese living in Fanada is distinet.ly higher (by abont 10 mm. ) J’or each decade than that I’oi 1li~tiWS lirin$ in China, especially in youn,v C 11~1middle-aged adults. In 1KJth a slight, hut steady increase in pressure occurs with advancing age and in the later decades (fifty to sixty-nine years) there is a sharp dsc which illlTl0St~ reilcht?s 1-M mm. In our subjects this may he iivconntetl for by the greater frequency of hypcrten,4on in the older melt.
400
Thus for the ages fifty to sixty-nine years, 21 subjects had systolic pressures above 140 mm., whereas in the earlier decades there were onlr 14 above this level. This is even more striking when we bear in mind the fact that the 31 cases with hypertension o~~ux!d in a total of 66 sllbjccts while the 14 yuui~gcr hypertcnsivcs were found in 173 subjects. The average pressure in Canadian Chinese is in fact the same as that I’or (hl~aw;s,~ white proplc 01 similar ages! living on this cont,inent Symonds,s Woley”) . The same conclusions hold true for the nvcra~es of diastolic pressure, though there is not such a significant, rise with ilcl~allcing age. Table 11’ shows that the average diastolic pressures of (.‘anadian Chinese arc higher than those of ihcir cwnl)atriots residing in C’hinn. RELATION
OF SYSTOLIC
BLOOD
PRESSURE
PRESSURE IN MM.
AGE
5-9
70. 79 so- 89 90. 99
100-109 110-119 120-129 130-139 140-149 150-159 160-169 170-179 180-189 190-199 ?cw209 210-219 -
Total
TO AGE IX 239 CHINESE IN
30-39
I
YEARS
411-.&!I -1 1 0
s
10 13 35 I ,s 3 1 ::
13
3
13 12 2 2
50-59 1 1 8 11 16 G 1
3 3
1
2
1
/
3
,
--t( I 31
I
50
--
Sl
-.
1 1
Relntio~~ of f$ytolic and Dia,stolic Blood Pt~cssu~~cto dc~e.-The levels of systolic and diastolic blood pressure :for each decade are shown in (185 or 77.1 Tables V and VI respectively. The majority of OUL ciIs('s per cent) a.re in the age, group between thirty and fifty-nine yrars. One hundred and seventy-four subjects (72.8 per cent,) hare systolic blood pressures ranging between 110 and 139 mm., whereas in 35 (l-L.6 per cent) the reading is above 140 mm. The largest, single group 01’ 71 casesoccurs in the 120-129 mm. division. It is seen how few C~SCS actually have pressures below 110 mm., thus esl~laining the higher mean pressure of Western Chinese as compared to those living in China. In the distribution of the diastolic records, 166 subjects (70.0 per cult) have rea.dings below 90 mm., of which 76 have a pressure of 80-89 mm. In 20 (8.4 l)er cent) a pathological readin,(7 of over 100 mm. was foui~~l. Here, too, really low f$~res arc rclativcxly u~~t'tmnw~~ ill 111~ cli;tstcd it+ pressures 01: Canadian Chinese.
402
THE
AMERICAN
HEART TABLE
*In shortly
2 subjects after the
diastolic onset of
the
pressure first
could (systolic)
JOURNAI.
VI
not
be phase.
recorded.
the
sound
disapw%wing
Uloo,d PWSSWC axl @b&g.-In a study of this kind, it is difficult to define precisely where obesitv begins. It is generally agreed, however, that an excess 01 2.5 per cent or more above the (MeLester, I3 Harrop14) standard or ideal weight, -for age and height, is to be considered abnormal. But many persons are found who are 20 pounds (9.0 kilos) or more above their ideal weight, and these I:all into the overweight class. Of our 239 Chinese, 11 were observed to b11 distinctly obese, and 12 were included in the second group of overweight individuals, giving a total Tn common wit,h white peaof 23 or 10 per cent in the obesity group. pie, the lat.er decades are subject. to ohesit.y ; thus 1 of the obese Chinese were in the fourth decade of life, 3 in the fifth and 9 in the sixth decade. When we come to examine the blood pressures of these, we find that, 5 obese subjects have art,erial hypertension ; i.e., a systolic blood pressure above 140 mm., and 6 have diast,olic pressures over 100 mm. There is therefore in this small group of overweight, C’hinese a higher incidence of hypertension (21.7 per cent) than in those o.l: normal or a,verage weight (10.1 per cent). This is in agreement with what, is generall! found, viz., that. high blood pressures occur with greater frequency in those who are obese than in those who are not. (Alvarez and Stanley,’ Symonds,s Hartman and Ghristlj) . It should be added that the diet of Canadian Chinese is ;I, liberal one and moderately well halancrcl. 111 Chins the natives subsist, largely on a vegetable diet. Hypertemiolz ilb Chinese.-A systolic pressure of 140 mm. Hg is usually regarded with suspicion at, any age, and in the present study 2 consecutive readings above this level are held to he pathological and the cases included in the hypertensive gtvnp. There were 27 subjects (11.2 per cent) with such elevated pressures. It is quite possible that a number of these ought not to be considered hypertensive in view of the well-known effect of nervousness and apprehension in producing a rise of systolic pressure. And though most 01’ the Chinese did not mani-
KEAKOWEIZ
:
KLOOD
PRESSURE
OJT CHINESE
IN
CANADA
403
fest any uneasiness, yet the procedure of taking blood pressure was a strange one to many. As mentioned before, 8 five-minute rest interval was allowed between the first, >md second reading to remove as much ol’ the IICI’VIJIIS factor 21s possible. ,I iiumher had undoubted hypertension with the systolic, just below or ill)OVe 200 mm., and in 12 Sub111 14 cases the heart was esjects the tliiIStOlic* \vilS o\‘El’ 100 111111. and in 6 o I) thcisc thcrc was contirmatory evidence of il mined, hypertensive disease mnnifest,ed hy cardiac enlargement and aecentuetion of the second aorfic sound at the base. In one subject. there was ;t. mitra1 insufficient\witI enlarged heart and ill another pronounce<{ peripheral arteriosclerosis. In 7 no evitlence of organic or valvular heart, disease could be rliceitcd by ordinaq- physical examination. The heart WNS also examined in 2% subjects whose blood pressures were within normal limits, and in 2 cdases rheumatic Avular heart disease \VilS detected. The IV?ITlili~ltl~~ were healthy. The frequency ol’ hypertension in C’hinese living in Canada is certainly ill marked contrast to its rarity in (‘hinese natives. FosteP states that among 4,000 C’hinese admissions to the medical service of the NllIl~lll-Jyillf? HOSpitill in C‘hina, he wits able to find less than 20 with a blood pressure ol’ 160 or over. In his private practice in New Englancl. however, 16 per cacnt of his office patients had pressures of 150 mm. or over. The etiology oC arterial hyl)crtcnsion remains obscure and several factors have been mentioned as contributory agents. Thus constitution, endocrine gland chan~cs, diet, climate and mode of living have all been suggested as causes. Of these environment and mode of living deserve attention. In China, the tempo of life is certainly at a slower pace, and nervous straill, so &x&erist.ic of Western civilizais rare among the natives, and tion, is relatively absent. Hypertension even white people after n short residence are found to have lowered hlood pressures. On the other hand, when the Chinese emigrate to this country, their blood pressures increase so that their average pressure is the same as that of the white inhabitants and hypertension is found frequently enough.
This work was undertaken to determine t,he blood pressure of Chinese living in Clanada for a number of years and to compare theil average pressure with that of the white inhabitants. The great majority of the subjects have been in Canada for ten years or more, and their average blood pressure is 10 mm. or more higher than that of Chinese natives for each de~adc. As a matter of fact, their pressures are equal to those reported for native West,crriers. The ast,onishing finding of hypertension in 11 per cent of our subjects compared to its rarity in China, suggests the importance of the -Ale of worry and
404
THE
AMERICAN
HEART
JOVRNAI;
nervous strain of western life, as well as dietary and other environmental fa.ctors, in the etiology o-f high blood pressure. In a small number of Canadian-born Chincsc the avwuge 1)rrssure was observed to be well above that reported for Chinese natives of similar age lwriods, ;igain eml)hasizing cnvironmcnt a~ :I in influencing blood I)ressun’. Ubesity oc!cuIwd it1 10 I)cr cwlt of the sul),jects. illld in I hesc h~pertensioii was not uncommon. 01’ lhc 39 iudividuals in whom the heart was examined, 6 were found to have hyl)ertensive heart discilsc ilnd 2 rheumat~ic valvular disease. fitdO
SUMMARY
AND
CONCI~OSIOKS
The average blood pressure of Chinese living in Canada for ten years or more is consistently higher (10 mm. Hg) than that reported for Chinese natives. Canadian Chinese have pressures the same as those of the white population. In this series hypert,ension occurs with SWprising frequency (11.2 per cent), in contrast, to its rarity in China. RIWFRI’NWS .,I
1
1. Cadbury, W. W.: The Blood Pressure of I;ormaI Cantonew Students, .irch. Int. Med. 30: 362 1922. 2. Cruickshank, E. W. iJ.: Physiological standards in North China, China N. J. 37: 1, 1923. 3. Kilborn, L. G.: l3lood Prcssnrc of Pzccl~wanese Students, c%ina M. J. 40: 1, 1926. Arch. tnt. Med. 40: 4. Foster, J. H.: Blood l’rcssurc of E’orcignrra in (‘hina, 35, 1937. ;5. Tung, C. L.: Blood Pressure of Northern Chinese Males, Chinese J. Physiol. 4: 117, 1930. G. Ying, Y. I’.: Blood Prcsxure of Healthy Tndividoals in Shaohing, (‘hina 11. .l. 40: 641, 1926. 7. Alvarez, TV. C., and Stanley, L. L.: Blood Pressure in G~lilO Prisoners and 400 Prison Guards, Arch. Int. Ned. 46: 17, 1930. of Healthy Men and Women, J. A. 31. A. s. Symends, B. : The Blood Pressure 80:
232,
1923.
9* . Woley, H. I’.: The Kormal Yariution of the Systolic Blood Pressure, .T. A. M. A. 55: 121, 1910. 10. Frost, IT. &I.: IIypertension and Longevity, Boston 11. 8~ 6. J. 193: 241, 19%. 11. Tung, C’. L.: The Blood Pressure of Chinese in China and in the U. S. A., Chinese J. Phyeiol. rep. ser. 1: 93, 1925. Hypotension of Foreigners in China, Arc.h. Int. Med. 40: I?. Idem : The Relative 1.53, 1937. J. S.: Sutrition xnd Diet in Health and Disease, Philadelphia, 13. MeLester, ea. 2, 1941,W. H. S;aunders & Co. Dirt in TXscasc, T%lxdelphia, 1930, P. Blakiston’s Son 14. Harrop, G. A., *Jr.: & co. Blood Pressure and Weight, Arch. tnt. 7.5. Hartman, 11. R., and (Christ. 1). 11.: Mea.
44:
16. Foster, J. Il.: Observations
877,
1929.
The Practice en Hylwrtensiou,
of
X
China and New England J. Med. 203: 1073, 1930.
With