Blood pressure and heart murmurs in a rural population in the ...

BLOOD PRESSURE AND HEART MURMURS91apex beat was recorded as being palpable or not,and the intercostal space in which it was located wasnoted. Cardiac murmurs were classified accordingto their intensity as recommended by Rose &Blackburn (14). No distinction was made betweenejection and pansystolic murmurs. Murmurs werealso classified according to their area of maximumintensity as apex and mitral, left lower border ofsternum (LLBS), pulmonary, aortic, or other.The age given by the subject was accepted if it didnot differ by more than 5 years from that previouslyrecorded at census. If the difference was more than5 years, the person was questioned on importantdates in the Republic's recent past; one fifth of thesubjects were placed in a different age group fromthat determined by the census.RESULTSIn all, 608 persons were examined (333 men and275 women), the overall response rate being 86 %.These appeared to be no significant differences withregard to age, sex, or geographical location amongthose who did not respond. Ninety-five percent ofthe subjects had been resident in the area for 5 yearsor more, over 90% were farmers, and 79% of thewomen and 48 % of the men had had no formalprimary education.The distributions of systolic and diastolic bloodpressures for all males and all females (Fig. 1 and 2)were approximately normal, with close similaritiesbetween males and females. The skew to the rightis slight but is more marked for systolic than fordiastolic blood pressure.The mean systolic and diastolic blood pressurelevels according to age and sex are given in Table Iand Fig. 3.Systolic blood pressureThe men showed no significant rise in meansystolic blood pressure level with age, whereas forwomen there was a consistent rise starting belowTable 1. Mean systolic and diastolic(pressures in kPa in parentheses)blood pressures in mmHg by age and sexMenWomen aAge group(years) Mean blood SD b Number Mean blood SD NumberpressurepressureSystolic25-34 120.1(16.0)11.2 81 117.6(15.6)15.5 6635-44 124.6(16.6)15.5 88 119.0(15.8)20.1 9445-54 122.7(16.3)21.8 75 124.3(16.5)19.1 5855-64 124.6(16.6)19.1 89 126.9(16.9)20.7 57Total 123.1(16.4)17.3 333 121.4(16.1)19.2 275Diastolic25-34 74.4(9.9)11.4 81 72.3(9.6)11.9 6635-44 77.0(10.2)11.6 88 74.8(9.9)11.3 9445-54 76.1(10.1)14.8 75 76.2(10.1)15.1 5855-64 77.5(10.3)13.2 89 75.9(10.1)13.5 57Total 76.3(1 0.1)12.7 333 74.7(9.9)12.8 275a Difference in mean blood pressure between women aged 25-34 years and those aged 55-64 yearsby the Student t test = 0.01 > P > 0.005.b SD = standard deviation.

92J. P. VAUGHANNE1]a11Qp_Males*---* Females__110-0-~~~~~~~~.~ ~- - 025-34 35-44 45-544e group in yearsSYSOLIC55-64 All a=Ie:eIJmen (r = 0.08, P>0.05) whereas, although it wasstill low for women, it was significant (r = 0.20,P

BLOOD PRESSURE AND HEART MURMURS93A stepwise multiple regression approach was usedand a lower level of P

94J. P. VAUGHANln Apex population was typical of a rural area and thatthe survey itself was sound.In the present survey, a rise in blood pressure with[1 _age occurred only in women and even this rise was20. _ ~a comparatively small one. Two surveys carried outII in Nigeria (6, 7) showed that mean blood pressures10lrose with age in both men and women, and Shaper& Saxton (8) found very similar findings among theBaganda tribe in Uganda. However, none of these25-34 35-44 three surveys were carried out in a truly rural35A44 45-54 55-64AillygeAg4e group in years population.% FDAI25-34 35-44 45-54Age grup in years55-64Fig. 4. The percentage of all subjects in each age/sexgroup with systolic murmurs (Grade 1 or more) withmaximum intensity at the apex or the left lower borderof the sternum.tomatic. Four were diagnosed as having pure mitralstenosis with no evidence of mitral incompetence orinvolvement of the other heart valves. None hadcardiac failure and none had had hospital treatmentfor heart complaints. The fifth person had a soft,blowing, early diastolic Grade 2 murmur maximumin the LLBS, suggesting aortic incompetence. Theprevalence of clinically detected mitral valvulardisease among women 25-64 years of age was, therefore,4 out of 275 (1.45%).DISCUSSIONThe survey area was chosen because the populationwas typical of the undeveloped rural areas of theUnited Republic of Tanzania. The sample wasrandom and the response rate high, with no evidencefor bias in the non-responders with regard to age,sex, or geographical area. The survey methodsfollowed standard recommended techniques andobservers were supervised and monitored for variationand bias. The only significant bias was foundto be a tendency by two observers to read higherdiastolic pressures. All these factors suggest theThe present survey is one of very few to reveallow blood pressures in Africa, particularly inAfrican Negro subsistence farming communities.Huizinga (2) mentions five communities in Africain which blood pressure did not appear to rise withage. Two were investigated by the author: the Fali(northern Cameroon) and the Kurumba (UpperVolta); two others are the Ituri Forest pygmies inZaire (17) and the Kalahari bushmen (18). Thefifth was a small mixed group of immigrants examinedby Shaper & Saxton (8). Similar findings have beenreported in a rural population in the Gambia (19),and reports from Papua New Guinea have suggestedan actual fall in mean blood pressure with age(20, 21).The 2 % prevalence for hypertension in this surveyis very low compared with other surveys in Africa,such as 23% in the Baganda in Uganda (8), 34%among persons 45 years old or more in Uganda(22), 5 % among tuberculosis outpatients in Ethiopia(23) and 20-30% in the inhabitants of Lagos city,Nigeria (7). In an analysis of inpatient admissionsreported by all hospitals in the United Republicof Tanzania for 1966-68, hypertension accountedfor 0.4% of all admissions (not including normalchildbirth) and for 20% of cardiovascular admissions.One quarter of all admissions for hypertension werein fact reported from a region with 7% of the totalpopulation of the country plus the capital city (4).Similar urban/rural differences have been reportedfrom South Africa, where hypertension was foundto be rare in the rural areas and considerably morecommon in the urban populations (24, 25). Studies inPapua New Guinea and the Pacific area have alsorevealed an almost total absence of hypertension inthe adult population (26, 27) and a review of communitieswithout apparent hypertension has recentlybeen published (3).Age has been found to be the most importantexplanatory variable in large studies employingmultiple regression analysis of cross-sectional data

BLOOD PRESSURE AND HEART MURMURS95in the United States of America (28-30), Israel (31),Belgium (32), and India (33). In the present study,age was found to be an " explanatory " variableonly in women. Some measure of body mass, suchas weight or relative weight, was also found to beimportant in these studies.Acheson & Florey (28) were able to explain about40% of the variance in blood pressure levels in theiranalysis of national data from the USA, whereasthe other studies mentioned above only explainedbetween 10% (32) and 23% (29, 30). The presentstudy explained less than 10% of the variance.The problems of diagnosing mitral valve lesionsin the tropics are common and great; Brockington& Edington (34) remarked in their clinicopathologicalstudy of heart disease in western Nigeria that theywere a "... major source of diagnostic difficultyin wards and postmortem rooms ". However, thepersons in this survey who were found to have adiastolic murmur most probably had some organicvalvular lesion and the prevalence rate for mitralvalve disease of 1.45% in women aged 25-64 yearsis quite a high but not unlikely rate (moreover, it isbased on only four cases). There was a notableabsence of diastolic murmurs in men.Systolic murmurs present quite a different picture.All the persons were examined by the author andthe prevalence figures for the presence of murmursmight be explained by observer error or bias.However, although this might partly account forthe high prevalence figures, it is unlikely to be theentire explanation because the figures themselveswere very high, the observations were consistentbetween men and women, and the age prevalencerates for apical murmurs remained constant whereasthose for murmurs maximum at the left lower borderof the sternum fell. Even if Grade 1 murmurs areignored, the proportion with Grade 2 or more wasstill surprisingly high; men 17 % and women 22 %. Allthese persons were apparently well. This contrastsmarkedly with hospital studies, where patients areusually given a diagnostic category. There are veryfew references in the literature to such " benign "systolic murmurs among hospital patients. However,Parker (35) found in Nairobi that in 6% of hiscardiac outpatients there was a systolic murmurand nothing else abnormal to be found.In community surveys, similar findings wereobtained by Mann et al. (17) in Ituri Forest pygmiesin Zaire, in whom 16% of 186 subjects had a Grade 2murmur or higher. Also, a cardiovascular survey inthe vicinity of the Albert Schweitzer Hospital inGabon revealed that "... a large amount of unexplainedcardiac disease exists, manifested mainlyby " organic" systolic murmurs, cardiomegaly orabnormal ECG's" (36).In the present survey, the prevalence of systolicmurmurs was similar in the two sexes, which suggeststhat causal factors are probably environmentalrather than genetic. Anaemia is not common orsevere enough to explain the high prevalence. Inthe tropics streptococcal infections are frequent, highASO titres are commonly found, acute rheumaticfever appears to take on clinically mild forms, andthere is a high prevalence of chronic rheumaticheart disease (37, 38). Could these systolic murmursrepresent the subclinical aftermath of such a pathologicalprocess?Why the proportion of LLBS murmurs decreasedin the older age groups is not clear. It might beexplained by affected persons dying earlier, the'lesion ' (whatever it might be) healing, or a cohortphenomenon showing itself by rising prevalence ratesin younger age groups. There is no way of differentiatingamong these possibilities with the presentdata. Some follow-up information on the personssurveyed might reveal the significance of such murmursand also what happens to them with time.ACKNOWLEDGEMENTS1 wish to thank the people who lived in the survey area for their cooperation, and the Dean and staff of theFaculty of Medicine, Dar es Salaam, for a great deal of help. I was greatly supported and guided in this project byProfessor C. Wood, Dr P. Hamilton, and Dr W. Miall. Particular thanks go to Dr Amri, Dr Mlay, Dr Mgone,Dr Malangalila, Dr Parma, and Dr Tesha who, as medical students, helped with the survey and remained enthusiasticthroughout. My thanks also go to Professor M. Backett and the staff in the Department of Community Health whowere very encouraging and helped with the analysis of the survey data.

96 J. P. VAUGHANRtSUMPPRESSION ARTERIELLE ET SOUFFLES CARDIAQUES DANS UNE POPULATION RURALEDE LA REPUBLIQUE-UNIE DE TANZANIEL'hypertension est fr6quemment constatee chez les maladessoign6s dans les h6pitaux tanzaniens, et la plupartdes enquetes sur la pression arterielle men&es au seind'autres populations d'Afrique noire confirment que lamoyenne de celle-ci pour les diff6rents groupes d'agene differe pas de celle qui s'6tablit dans des populationseuropeennes. L'insuffisance cardiaque globale et les cardiopathiesvalvulaires sont 6galement couramment diagnostiqueeschez les malades adultes; quant aux soufflescardiaques souvent perqus a l'auscultation, ils pr6sentent,pour la plupart, un caractere benin et il est gen6ralementdifficile de les associer a un trouble organique determine.La presente 6tude a ete faite pour etablir la prevalencede l'hypertension et des souffles cardiaques dans unepopulation rurale a 6conomie agricole de subsistance.Elle a port6 sur un echantillon al6atoire de 608 individusages de 25 a 64 ans qui ont ete examines en appliquantles methodes habituelles de controle cardio-vasculaire.Chez les femmes, la moyenne de la pression arteriellesystolique s'accroit legerement avec l'age, mais non lapression diastolique; chez les hommes, on n'a pasconstat6 d'6l6vation avec l'Age de la pression soitsystolique, soit diastolique. Deux pour cent des sujetspr6sentaient de l'hypertension (pression 6gale ou superieurea 160/95). L'analyse par r6gression multiple amontr6 que l'age constituait une variable significative ence qui concerne la pression systolique et diastolique chezles femmes, mais non chez les hommes. Elle a aussipermis d'etablir que 1'6paisseur du pli cutane figuraitparmi les variables en relation avec le niveau de la pressionart6rielle chez les individus des deux sexes. Quoiqu'il en soit, ni l'age ni les mesures anthropometriquesn'ont pu expliquer plus de 10% de la variance chez leshommes ou chez les femmes.Un souffle systolique de degre egal ou superieur a 2a e perqu chez 17% des hommes et 22% des femmes.Son intensite maximale se situait a l'apex et dans laregion mitrale (pour 53% des cas) et dans la partieinferieure du bord gauche du sternum (pour 31 % des cas).La proportion de sujets pr6sentant un souffle apexien n'apas paru varier en fonction du groupe d'age, alors quela perception d'un souffle au bord inferieur gauche dusternum diminuait de maniere appreciable avec l'age.On a constate une forte correlation entre la presence d'unbattement de l'apex contre la cage thoracique et celled'un souffle systolique du degre 2 ou plus, ainsi quecelle d'un certain d6ficit du taux d'hemoglobine. Unsouffle diastolique a ete perqu chez 4 des 275 femmesexamin&es et 4 d'entre elles pr6sentaient une cardiopathiemitrale asymptomatique, le taux de morbidit6 par cettemaladie s'etablissant ainsi a 15 pour 1000 femmes ag6esde 25 a 64 ans. La cause de la forte prevalence du soufflesystolique n'est pas connue, mais on peut se demanders'il ne constitue pas souvent une sequelle d'infectionstreptococcique.REFERENCES1. LOWENSTEIN, F. W. Blood pressure in relation toage and sex in the tropics and subtropics. Lancet,1: 389-392 (1961).2. HUIZINGA, J. Casual blood pressure in populations.In: Vorster, D. J. M., ed. Human biology of environmentalchange. London, International BiologicalProgramme, 1972, p. 164.3. SHAPER, A. G. Communities without hypertension.In: Shaper, A. G. et al., ed. Cardiovascular diseasein the tropics. London, British Medical Association,1974, p. 77.4. VAUGHAN, J. P. Cardiovascular diseases seen inTanzanian hospitals 1966-68. East African medicaljournal, 54: 373-379 (1977).5. ABRAHAMS, D. G. ET AL. The systemic blood pressurein a rural West African community. West Africanmedical journal, 9: 45-58 (1960).6. AKINKUGBE, 0. 0. & Ojo, 0. A. Arterial pressuresin rural and urban populations in Nigeria. Britishmedical journal, 2: 222-224 (1969).7. JOHNSON, 0. T. Arterial blood pressures and hypertensionin an urban African population sample.British journal of preventive and social medicine,25: 26-33 (1971).8. SHAPER, A. G. & SAXTON, G. A. Blood pressure andbody build in a rural community in Uganda. EastAfrican medical journal, 46: 228-245 (1969).9. NHONOLI, A. M. Heart disease in Dar es Salaam.East African medical journal, 45: 118-121 (1968).10. SPENCER, S. S. & MAKENE, W. J. Rheumatic heartdisease in Tanzania. East African medical journal,49: 909-920 (1972).11. VAUGHAN, J. P. Brief review of cardiovasculardisease in Africa. Transactions of the Royal Societyof Tropical Medicine and Hygiene, 71: 226-231 (1977).

BLOOD PRESSURE AND HEART MURMURS 9712. NHONOLI, A. M. The incidence of hypertensive heartdisease in Dar es Salaam. East African medicaljournal, 46: 55-57 (1969).13. WRIGHT, B. M. & DORE, C. F. A random zerosphygmomanometer. Lancet, 1: 337-338 (1970).14. ROSE, G. A. & BLACKBURN, H. Cardiovascularsurvey methods. Geneva, World Health Organization,1968 (Monograph Series, No. 56).15. ROSE, G. A. Standardisation of observers in bloodpressure measurement. Lancet, 1: 673-674 (1965).16. WHO Technical Report Series, No. 168, 1959(Hypertension and coronary heart disease: classificationand criteria for epidemiological studies. Firstreport of the Expert Committee on CardiovascularDiseases and Hypertension).17. MANN, G. V. ET AL. Cardiovascular disease inAfrican pygmies. Journal of chronic diseases, 15:341-371 (1962).18. KAMINER, B. & LUTZ, W. P. W. Blood pressure inthe bushmen of the Kalahari Desert. Circulation,32: 289-295 (1960).19. REE, G. H. Arterial pressures in a West African(Gambian) rural population. Journal of tropicalmedicine and hygiene, 76: 65-70 (1973).20. MADDOCKS, I. & RovIN, L. A New Guinea populationin which blood pressure appears to fall as ageadvances. Papua New Guinea medical journal,8: 17-21 (1965).21. STANHOPE, J. M. Population studies in Papua NewGuinea. Singapore medicaljournal, 14: 228-229(1973).22. IKEME, A. C. ET AL. A survey for cardiovasculardisease in middle aged Ugandans. Bulletin of theWorld Health Organization, 48: 751-753 (1973).23. PARRY, E. H. 0. Ethiopian cardiovascular studies.III: the casual blood pressure in Ethiopian highlandersin Addis Ababa. East African medicaljournal, 46: 246-256 (1969).24. SCOTCH, N. A. A preliminary report on the relationof sociocultural factors to hypertension among theZulu. Annals of the New York Academy of Sciences,84: 1000-1009 (1960).25. EDGINGTON, M. E. ET AL. Disease patterns in a SouthAfrican rural Bantu population. South Africanmedical journal, 46: 968-976 (1972).26. MADDOCKS, I. Possible absence of essential hypertensionin two complete Pacific Island populations.Lancet, 2: 396 (1961).27. PRIOR, Epidemiology of cardiovascular diseases inAsian-Pacific region. Singapore medical journal,14: 223-227. (1973).28. ACHESON, R. M. & FLOREY, C. DU V. Predictingblood pressure from age, physique, blood glucoseand serum cholesterol in a national sample of theUSA (1960-62). Archives roumaines de pathologieexperimentale et de microbiologie, 28: 131-136 (1969).29. STAMLER, J. ET AL. Multivariate analysis of therelationship of six variables to blood pressure:findings from Chicago community surveys, 1965-71Journal of chronic diseases, 28: 499-525 (1975).30. STAMLER, J. ET AL. Multivariate analysis of therelationship of seven variables to blood pressure:findings of the Chicago Heart Association detectionproject in industry, 1967-72. Journal of chronicdiseases, 28: 527-548 (1975).31. SIVE, P. H. ET AL. Distribution and multiple regressionanalysis of blood pressure in 10,000 Israeli men.American journal of epidemiology, 93: 317-327 (1971).32. KESTELOOT, H. & VAN HOUTE, 0. An epidemiologicsurvey of arterial blood pressure in a large malepopulation group. American journal of epidemiology,99: 14-29 (1974).33. BAGCHI, S. C. & INDRAYAN, A. Multivariate analysisof blood pressure correlates in an Indian urbancommunity. Indian journal of public health, 18:93-104 (1973).34. BROCKINGTON, I. F. & EDINGTON, G. M. Adultheart disease in western Nigeria: a clinicopathologicalsynopsis. American heart journal, 83: 27-40(1972).35. PARKER, A. H. T. Cardiac disorders in Nairobi.East African medical journal, 50: 530-536 (1973).36. MILLER, D. C. ET AL. Survey of cardiovasculardisease among Africans in the vicinity of the AlbertSchweitzer Hospital in 1960. American journal ofcardiology, 10: 432-446 (1962).37. SHAPER, A. G. Cardiovascular disease in the tropics.British medical journal, 3: 682-686 (1972).38. STOLLERMAN, G. H. Streptococcus, rheumatic feverand rheumatic heart disease. In: Shaper, A. G. et al.,ed. Cardiovascular disease in the tropics. London,British Medical Association, 1974, pp. 7-21.