- Email: [email protected]
Prevalence of hypertension in Sri Lanka. A large population study in the central province
Public Health (1988), 102, 455~162
Prevalence of Hypertension in Sri Lanka. A Large P o p u l a t i o n S t u d y in t h e Central P r o v i n c e S h a n t h i M e n d i s 1"2 MBBS. MRCP (London), Consulting Physician, Senior Lecturer. Department of Medicine
P. Ranasinghe 1,2 Registrar
Professor B. D. Dharmasena 1 MD, FRCP, FRCPE, Professorof Medicine
1Faculty of Medicine; 2 Teaching Hospital Peradeniva, Sri Lanka
Hypertension is frequently seen among hospital patients in the Republic of Sri Lanka. However, the prevalence of hypertension in Sri Lanka is not known. During 1984 through 1986, 10,005 Sri Lankan adults were screened for hypertension at the Teaching Hospital, Peradeniya. They were between 20 and 84 years of age and were visitors of inpatients of the Teaching Hospital, Peradeniya. The majority were from areas in the central province of Sri Lanka and belonged to the middle and lower social classes. 60.6% of the screenees were males and 39.4% were females. Standard blood pressure survey methods as recommended by WHO were used to measure the blood pressure. The prevalence of hypertension among Sri Lankans, was 435/1,000. 299.4/1,000 had mild hypertension (diastolic blood pressure 90 to 94mmHg), 105.6/1,000 persons had hypertension of moderate severity (DBP 95 to 109 mm Hg). 30.8/1,000 persons had severe hypertension (DBP 110mm Hg or above). The prevalence of elevated blood pressure increased with age in both sexes up to the 7th decade.
Introduction Hospital data suggest that cardiovascular disease is a leading cause of morbidity and mortality in Sri Lanka. However, the prevalence of hypertension in the general population in Sri Lanka is not known. The objective of this study was to measure blood pressure levels and obtain data on the prevalcncc of hypertension in Sri Lanka.
Methodology From Dccember 1984 to February 1986 a total o f 10,005 individuals were screened for hypertension at the Teaching Hospital, Peradeniya. They were between 20 and 84 years of age and were visitors of inpatients o f the hospital. They were from areas in the ccntral province of Sri Lanka and belonged to middle and lower social class. The observers were trained and supervised during the survey by the authors. A singlc blood pressure taken in the sitting position was recorded. Systolic blood pressure and phase 5 diastolic blood pressure were recorded by means of a mercury sphygmomanometer to the nearest 2 mm Hg. © The Societyof Community Medicine, 1988
S. Mendis, P. Ranasinghe and B. D. Dharmasena
456
Routinely all persons with fifth phase diastolic blood pressure above 90 m m Hg and/or systolic blood pressure above 180 mm H g were referred to the 1st author for evaluation and follow-up.
Results The age and sex composition of the people screened are presented in Table I. All age strata of the adult population are represented. Females contributed 39.4% of screenees and males 60.6%. The proportion of study subjects living in an urban environment was 14.4%. 21,5% o f the total population o f Sri Lanka live in an urban environment. Table II shows the proportion o f urban populations in each administrative province o f Sri L a n k a for census year 1981. The majority o f patients (70%), in the study sample were from Central and Uva provinces. The rest were from Sabaragamuwa, N o r t h Central and N o r t h Western Provinces. Table I
Age and sex distribution o f persons screened
Age Years 21
N H V
Male 458 59 7.5
Female
Total
317 41 8
775 100 8
N 21-30 H V
1,948 70 32
827 30 21
2,775 100 28
N 31-40H V
1,532 63 25
903 37 23
2,435 100 24
N 41-50H V
955 54 16
820 46 21
1,775 100 18
N 51~50H V
100 52 12
659 48 17
1,359 100 14
N 61-70H V
368 54 6
315 46 8
683 100 7
N 71 + H V
108 53 2
95 47 2
203 100 2
N Total H V
6,069 61 100
3,936 39 100
10,005 100 100
N: indicates number of persons H: horizontal (row) percentage V: vertical (column) percentage
Hypertension & Sri Lanka Table II
457
Urbanisation of the population in Sri Lanka by province for census year 1981
Administrative area
Percentage urbanism
Central Province Uva Province Sabaragamuwa Province North Central Province North Western Province Southern Province Northern Province Eastern Province Western Province
11. ! 6.2 7.6 7.3 6.2 14.9 28.0 22.2 46.6
Sri Lanka
21.5
Source: Department of Census and Statistics
Table III c o m p a r e s the monthly income of the study sample with that of the total p o p u l a t i o n as a whole. The mean systolic and diastolic b l o o d pressures by age a n d sex are shown in Tables IV and V, together with the s t a n d a r d deviations of the means. The mean systolic b l o o d pressure was progressively higher with age for both sexes. V a r i a t i o n a m o n g individuals also was greater with increasing age as reflected by larger s t a n d a r d deviations. Until the age of 60 higher mean systolic blood pressures were found in men. A progressively higher mean diastolic blood pressure was recorded with increasing age but somewhat differently from systolic with flattening at a b o u t 60 years of age. Variability of diastolic b l o o d pressure also tended to increase with age but n o t as consistently as for systolic b l o o d pressure. The mean diastolic b l o o d pressure was higher in men than in women until the age of 70 years. Table llI Comparison of monthly income of households of study population with data obtained from national socioeconomic survey 1969/1970 Income (Sri Lanka Rupees)
Below 100 100--199 200-299 400-599 600-799 800-899 Over 1,000
National socio-economic survey 1969/70 Urban (% of total)
Rural (% of total)
3.5 17.7 39.6 18.1 9.0 5.2 6.9
9.4 36.7 37.0 11.1 3.8 1.1 0.9
Source: Department of Census and Statistics
Blood pressure survey population
2.0 20.5 40.1 18.8 10.9 4.0 3.7
458
S. Mendis, P. Ranasinghe and B. D. Dharmasena Table IV
Systolic Pressure Means and Standard Deviations (mmHg)
Age (years)
Males
Females
113.8 118.2 120.4 125.5 132.7 135.8 136.5
111.2 112.9 117.9 124.8 130.8 136.1 138.6
Systolic Standard Deviation 20 10.9 21-30 11.2 31-40 13.0 41-50 15.1 51-60 14.5 61-70 22.3 71 + 36.3
10.1 9.6 13.7 18.8 17.3 22.2 26.2
Systolic Means 20 21-30 31-40 41-50 51~50 61-70 71 +
Table V
Diastolic Pressure Means and Standard Deviations (mmHg)
Age (years)
Males
Females
75.3 78.5 80.8 84.0 86.9 87.3 86.8
73.6 75.2 78.5 82.7 85.6 86.5 88.2
Diastolic Standard Deviation 20 8.6 21-30 9.7 31-40 10.6 41-50 l 1.2 51~50 12.8 61-70 13.4 71 + 13.6
8.9 9.1 10.8 10.5 8.5 13.9 14.9
Systolic Means 20 21-30 31-40 41-50 51-60 61-70 71 +
T a b l e VI shows the rate o f prevalence o f elevated b l o o d pressure o f different severity in the 10,005 persons screened. 299.4/1,000 h a d a n elevated diastolic b l o o d pressure o f 90 m m Hg or more. U s i n g a diastolic b l o o d pressure m e a s u r e m e n t o f 94 m m H g as the cut-off p o i n t 105.6/1,000 p e r s o n s h a d elevated b l o o d pressures. 30.8/1,000 persons had diastolic b l o o d pressures equal to or a b o v e I l0 m m Hg.
Hypertension in Sri Lanka Table VI
Elevated blood pressure rate per 1,000
Age (years) Diastolic >~90 mm Hg 20 21-30 31-40 41-50 51-60 61-70 71 + Total Diastolic>~95 mm Hg 20 21-30 31-40 41-50 51~50 61-70 71 + Total Diastolic>~ 110 mm Hg 20 21-30 31-40 41-50 51 60 61-70 71 + Total
459
Males
Females
Total
I 11.9 194.9 291.7 481.2 498.3 643.5 544.3
86.1 108.9 195.8 388.6 486.5 492.9 568.1
102.1 169.3 256.8 438.9 492.5 568.7 552.8
312.5
278.3
299.4
0 43.7 86.7 192.4 246.6 319.4 227.8
3.7 23.2 57.2 129.5 208.0 239.4 318.2
1.4 37.4 75.9 163.7 227.4 279.7 260.2
109.3
99.7
105.6
0 5.2 20.4 49.3 86.7 125,0 75.9
0 1.2 13.7 41.8 68.8 112.7 136.4
0 4.0 17.9 45.9 77.8 118.9 97.6
29.8
32.3
30.8
The prevalence of elevated b l o o d pressure increased with age in both sexes up to the 7th decade. Based on the 95 mm Hg cut-off point the rate per 1,000 people o f elevated diastolic b l o o d pressure rose from 1.4 for those under 20 years to 279.7 for those 61-70 years o f age. A similar gradient was found using 110 mm Hg or m o r e as criterion starting at 0/1,000 for those under 20 years and reaching a prevalence o f 118.9/1,000 for those in the 7th decade. The present survey is the only published study on the prevalence o f hypertension in Sri Lankans. Discussion O u r d a t a on the variation of blood pressure in Sri L a n k a n s with age a n d sex are not in agreement with those of Bibile et al. (1949). 1 They reported that systolic a n d diastolic blood pressure of adult Sri L a n k a n s do not vary significantly in males and females a n d do not increase significantly with age. The d a t a o f the present study show that the mean systolic and diastolic b l o o d pressure are significantly higher in males than in females a n d that the
460
S. Mendis, P. Ranasinghe and B. D. Dharmasena 650 600 550 500 450
•
/
//~] o
400
///
"
,/
,
cD rh 3 5 0
J
•
"S
....
//
//
//
..-'
...'"
.,.""
"".-......,. "-.....
"'.....
300
E
2
250 200 150 100
Y //
50
0<20 <20
20-29 21 30
30-39 31-40
40-49 41 50
I 50-54 51-60
L .J 60-64 />65 CHEC program 61-70 >71 present study
A g e (years)
Figure 1 Comparison of prevalence of elevated blood pressure at screening (diastolic = 90 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... wmte male; --- white female).
mean systolic and diastolic blood pressures also increase significantly with age in adult Sri Lankans. Although there are several reports on blood pressure distribution and prevalence o f hypertension in populations, the C o m m u n i t y Hypertension Evaluation Clinic ( C H E C ) P r o g r a m m e conducted by Stamler et al. (1976) 2 is most comparable to the present study because it involves volunteer subjects and casual sitting pressures performed by trained health personnel. C H E C found 24.7% with diastolic blood pressure levels ~>90mm Hg, 11.6% with diastolic levels >~95 turn H G and 2.6% with diastolic levels >~ 110 m m Hg. In the present study, 29.9% had a diastolic blood pressure 1>90 m m Hg. 10.6% had a diastolic blood pressure ~>95 m m Hg and 3.8% had a diastolic blood pressure ~> 110 m m Hg. There appears to be a larger n u m b e r o f mild hypertensives (>~90 m m Hg) a m o n g Sri Lankan adults when compared to Americans. The prevalence of moderate ( > ~ 9 5 m m H g ) and severe hypertension (~> l l 0 m m Hg) in Sri Lankans is comparable to that o f Americans. The data o f the present study also compares closely to the 22.3% prevalence o f diastolic
Hypertension in Sri Lanka
461
levels >_-90m m Hg and 10.8% prevalence o f diastolic levels />95 m m H g in Milwaukee? However, a study of blood pressure in a Scottish town 4 yielded higher prevalence rates of mild and moderate hypertension. Out o f 3,001 subjects screened in the Scottish T o w n o f Renfrew, 39.8% had diastolic blood pressures/> 90 m m H g and 25.8% had diastolic blood pressures >_-95m m Hg. The prevalence o f hypertension in Sri Lankans (44.3%) in this survey is higher than those reported in some African communities, such as 34% a m o n g persons 45 years old or more in U g a n d a 5 and 20~30% in the inhabitants of Lagos city in Nigeria. 6 Figures 1, 2 and 3 c o m p a r e the prevalence of hypertension o f different grades of severity in Sri Lankans and Black and White Americans. Prevalence of hypertension in Sri Lankans appears to be higher than in white Americans and less than in Black Americans. The stress of living in urban America, a large salt intake and hereditary influences have all been suggested as possible causes for an increased prevalence o f hypertension a m o n g blacks. 7,~ The average daily intake o f salt in Sri Lankans has been reported to be as high as 8.7 grams. 9 There is considerable evidence indicating dietary salt as a major factor in the pathogenesis o f hypertension. 1° The high salt intake m a y be a possible causative factor for the high prevalence of hypertension a m o n g Sri Lankans. Furthermore, if current therapeutic trials show benefit to the health of the c o m m u n i t y from treating 'mild' as well as ' m o d e r a t e ' hypertension, the presence o f a large number of 'mild' hypertensives in the population will have important implications for the resources of the health care system. 500 450 400 350
250
.// 2
/
/ :...'.. ......... . ..... ;;; . . . . . . . . . . . . . "
5o 0 <20
I 20-29
I 3 0 39
<20
21-30
31-40
I 40-49
I 50-54
I 60-64
I ~>65-CHEC program
41-50
51-60
61-70
>71 present study
A g e (years)
Figure 2 Comparison of prevalence of elevated blood pressure at screening (diastolic = 95 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... wlalte male; --- white female).
S. Mendis, P. Ranasinghe and B. D. Dharmasena
462 500 450 400 35O o300
46 25o £3
E 200
Z 150 1O0 0 0
/'"
<20 <20
20-29 21 30
~T. ....................................
30-39 31-40
40 49 41-50
50-54 51 60
J
60 64 ~>65-CHEC program 61 70 >71 present study
A g e (years)
Figure 3 Comparison of prevalence of elevated blood pressure at screening (diastolic = 1 I0 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... white male; --- white female).
Acknowledgements W e wish to t h a n k the final year Medical U n d e r g r a d u a t e s o f the F a c u l t y o f Medicine, University o f Peradeniya, Sri L a n k a , w h o participated in the c o n d u c t o f this survey and Mr. Suraweera w h o helped in the analysis o f data. This project was s u p p o r t e d by a g r a n t f r o m the University o f Peradeniya, Sri L a n k a .
References 1. Bibile, S. W., Cullambine, H., Kirthisinghe, C., Watson, R. S. & Wikramanayake, T. (1949). Ceylon Journal of Medical Science, 6, 79-82. 2. Stamler, J., Stamler, R., Riedlinger, W. F., Alegra, G. & Roberts, R. H. (1976). Journal of the American Medical Association, 35, 2299. 3. Itskovitz, H. D., Kocher, M. S., Anderson, A. J. & Rimm, A. A. (1977). Journalofthe American Medical Association, 238, 864. 4. Hawthorne, V. H., Greaves, D. A. & Beevers, D. G. (1974). British Medical Journal, 3, 600-603. 5. Ikeme, A. C. et al. (1973). Bulletin of the Worm Health Organization, 48, 751-753. 6. Johnson, O. T. (1971). British Journal of Preventive and Social Medicine, 25, 26-33. 7. Boyle, E. Jr. (1970). Journal of the American Medical Association, 13, 1637. 8. Stamler, J., Stamler, R. & Pullman, J. N. (1967). Epidemiology of Hypertension, p.122. New York: Grune and Stratton. 9. Pallemulle, L., Mendis, S. & Perera, P. L. P. (1983). Proceedings of the Kandy Society of Medicine, 6, 10. 10. Dehl, L. K. (1972). American Journal of Clinical Nutrition, 25, 23 I.
Prevalence of Hypertension in Sri Lanka. A Large P o p u l a t i o n S t u d y in t h e Central P r o v i n c e S h a n t h i M e n d i s 1"2 MBBS. MRCP (London), Consulting Physician, Senior Lecturer. Department of Medicine
P. Ranasinghe 1,2 Registrar
Professor B. D. Dharmasena 1 MD, FRCP, FRCPE, Professorof Medicine
1Faculty of Medicine; 2 Teaching Hospital Peradeniva, Sri Lanka
Hypertension is frequently seen among hospital patients in the Republic of Sri Lanka. However, the prevalence of hypertension in Sri Lanka is not known. During 1984 through 1986, 10,005 Sri Lankan adults were screened for hypertension at the Teaching Hospital, Peradeniya. They were between 20 and 84 years of age and were visitors of inpatients of the Teaching Hospital, Peradeniya. The majority were from areas in the central province of Sri Lanka and belonged to the middle and lower social classes. 60.6% of the screenees were males and 39.4% were females. Standard blood pressure survey methods as recommended by WHO were used to measure the blood pressure. The prevalence of hypertension among Sri Lankans, was 435/1,000. 299.4/1,000 had mild hypertension (diastolic blood pressure 90 to 94mmHg), 105.6/1,000 persons had hypertension of moderate severity (DBP 95 to 109 mm Hg). 30.8/1,000 persons had severe hypertension (DBP 110mm Hg or above). The prevalence of elevated blood pressure increased with age in both sexes up to the 7th decade.
Introduction Hospital data suggest that cardiovascular disease is a leading cause of morbidity and mortality in Sri Lanka. However, the prevalence of hypertension in the general population in Sri Lanka is not known. The objective of this study was to measure blood pressure levels and obtain data on the prevalcncc of hypertension in Sri Lanka.
Methodology From Dccember 1984 to February 1986 a total o f 10,005 individuals were screened for hypertension at the Teaching Hospital, Peradeniya. They were between 20 and 84 years of age and were visitors of inpatients o f the hospital. They were from areas in the ccntral province of Sri Lanka and belonged to middle and lower social class. The observers were trained and supervised during the survey by the authors. A singlc blood pressure taken in the sitting position was recorded. Systolic blood pressure and phase 5 diastolic blood pressure were recorded by means of a mercury sphygmomanometer to the nearest 2 mm Hg. © The Societyof Community Medicine, 1988
S. Mendis, P. Ranasinghe and B. D. Dharmasena
456
Routinely all persons with fifth phase diastolic blood pressure above 90 m m Hg and/or systolic blood pressure above 180 mm H g were referred to the 1st author for evaluation and follow-up.
Results The age and sex composition of the people screened are presented in Table I. All age strata of the adult population are represented. Females contributed 39.4% of screenees and males 60.6%. The proportion of study subjects living in an urban environment was 14.4%. 21,5% o f the total population o f Sri Lanka live in an urban environment. Table II shows the proportion o f urban populations in each administrative province o f Sri L a n k a for census year 1981. The majority o f patients (70%), in the study sample were from Central and Uva provinces. The rest were from Sabaragamuwa, N o r t h Central and N o r t h Western Provinces. Table I
Age and sex distribution o f persons screened
Age Years 21
N H V
Male 458 59 7.5
Female
Total
317 41 8
775 100 8
N 21-30 H V
1,948 70 32
827 30 21
2,775 100 28
N 31-40H V
1,532 63 25
903 37 23
2,435 100 24
N 41-50H V
955 54 16
820 46 21
1,775 100 18
N 51~50H V
100 52 12
659 48 17
1,359 100 14
N 61-70H V
368 54 6
315 46 8
683 100 7
N 71 + H V
108 53 2
95 47 2
203 100 2
N Total H V
6,069 61 100
3,936 39 100
10,005 100 100
N: indicates number of persons H: horizontal (row) percentage V: vertical (column) percentage
Hypertension & Sri Lanka Table II
457
Urbanisation of the population in Sri Lanka by province for census year 1981
Administrative area
Percentage urbanism
Central Province Uva Province Sabaragamuwa Province North Central Province North Western Province Southern Province Northern Province Eastern Province Western Province
11. ! 6.2 7.6 7.3 6.2 14.9 28.0 22.2 46.6
Sri Lanka
21.5
Source: Department of Census and Statistics
Table III c o m p a r e s the monthly income of the study sample with that of the total p o p u l a t i o n as a whole. The mean systolic and diastolic b l o o d pressures by age a n d sex are shown in Tables IV and V, together with the s t a n d a r d deviations of the means. The mean systolic b l o o d pressure was progressively higher with age for both sexes. V a r i a t i o n a m o n g individuals also was greater with increasing age as reflected by larger s t a n d a r d deviations. Until the age of 60 higher mean systolic blood pressures were found in men. A progressively higher mean diastolic blood pressure was recorded with increasing age but somewhat differently from systolic with flattening at a b o u t 60 years of age. Variability of diastolic b l o o d pressure also tended to increase with age but n o t as consistently as for systolic b l o o d pressure. The mean diastolic b l o o d pressure was higher in men than in women until the age of 70 years. Table llI Comparison of monthly income of households of study population with data obtained from national socioeconomic survey 1969/1970 Income (Sri Lanka Rupees)
Below 100 100--199 200-299 400-599 600-799 800-899 Over 1,000
National socio-economic survey 1969/70 Urban (% of total)
Rural (% of total)
3.5 17.7 39.6 18.1 9.0 5.2 6.9
9.4 36.7 37.0 11.1 3.8 1.1 0.9
Source: Department of Census and Statistics
Blood pressure survey population
2.0 20.5 40.1 18.8 10.9 4.0 3.7
458
S. Mendis, P. Ranasinghe and B. D. Dharmasena Table IV
Systolic Pressure Means and Standard Deviations (mmHg)
Age (years)
Males
Females
113.8 118.2 120.4 125.5 132.7 135.8 136.5
111.2 112.9 117.9 124.8 130.8 136.1 138.6
Systolic Standard Deviation 20 10.9 21-30 11.2 31-40 13.0 41-50 15.1 51-60 14.5 61-70 22.3 71 + 36.3
10.1 9.6 13.7 18.8 17.3 22.2 26.2
Systolic Means 20 21-30 31-40 41-50 51~50 61-70 71 +
Table V
Diastolic Pressure Means and Standard Deviations (mmHg)
Age (years)
Males
Females
75.3 78.5 80.8 84.0 86.9 87.3 86.8
73.6 75.2 78.5 82.7 85.6 86.5 88.2
Diastolic Standard Deviation 20 8.6 21-30 9.7 31-40 10.6 41-50 l 1.2 51~50 12.8 61-70 13.4 71 + 13.6
8.9 9.1 10.8 10.5 8.5 13.9 14.9
Systolic Means 20 21-30 31-40 41-50 51-60 61-70 71 +
T a b l e VI shows the rate o f prevalence o f elevated b l o o d pressure o f different severity in the 10,005 persons screened. 299.4/1,000 h a d a n elevated diastolic b l o o d pressure o f 90 m m Hg or more. U s i n g a diastolic b l o o d pressure m e a s u r e m e n t o f 94 m m H g as the cut-off p o i n t 105.6/1,000 p e r s o n s h a d elevated b l o o d pressures. 30.8/1,000 persons had diastolic b l o o d pressures equal to or a b o v e I l0 m m Hg.
Hypertension in Sri Lanka Table VI
Elevated blood pressure rate per 1,000
Age (years) Diastolic >~90 mm Hg 20 21-30 31-40 41-50 51-60 61-70 71 + Total Diastolic>~95 mm Hg 20 21-30 31-40 41-50 51~50 61-70 71 + Total Diastolic>~ 110 mm Hg 20 21-30 31-40 41-50 51 60 61-70 71 + Total
459
Males
Females
Total
I 11.9 194.9 291.7 481.2 498.3 643.5 544.3
86.1 108.9 195.8 388.6 486.5 492.9 568.1
102.1 169.3 256.8 438.9 492.5 568.7 552.8
312.5
278.3
299.4
0 43.7 86.7 192.4 246.6 319.4 227.8
3.7 23.2 57.2 129.5 208.0 239.4 318.2
1.4 37.4 75.9 163.7 227.4 279.7 260.2
109.3
99.7
105.6
0 5.2 20.4 49.3 86.7 125,0 75.9
0 1.2 13.7 41.8 68.8 112.7 136.4
0 4.0 17.9 45.9 77.8 118.9 97.6
29.8
32.3
30.8
The prevalence of elevated b l o o d pressure increased with age in both sexes up to the 7th decade. Based on the 95 mm Hg cut-off point the rate per 1,000 people o f elevated diastolic b l o o d pressure rose from 1.4 for those under 20 years to 279.7 for those 61-70 years o f age. A similar gradient was found using 110 mm Hg or m o r e as criterion starting at 0/1,000 for those under 20 years and reaching a prevalence o f 118.9/1,000 for those in the 7th decade. The present survey is the only published study on the prevalence o f hypertension in Sri Lankans. Discussion O u r d a t a on the variation of blood pressure in Sri L a n k a n s with age a n d sex are not in agreement with those of Bibile et al. (1949). 1 They reported that systolic a n d diastolic blood pressure of adult Sri L a n k a n s do not vary significantly in males and females a n d do not increase significantly with age. The d a t a o f the present study show that the mean systolic and diastolic b l o o d pressure are significantly higher in males than in females a n d that the
460
S. Mendis, P. Ranasinghe and B. D. Dharmasena 650 600 550 500 450
•
/
//~] o
400
///
"
,/
,
cD rh 3 5 0
J
•
"S
....
//
//
//
..-'
...'"
.,.""
"".-......,. "-.....
"'.....
300
E
2
250 200 150 100
Y //
50
0<20 <20
20-29 21 30
30-39 31-40
40-49 41 50
I 50-54 51-60
L .J 60-64 />65 CHEC program 61-70 >71 present study
A g e (years)
Figure 1 Comparison of prevalence of elevated blood pressure at screening (diastolic = 90 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... wmte male; --- white female).
mean systolic and diastolic blood pressures also increase significantly with age in adult Sri Lankans. Although there are several reports on blood pressure distribution and prevalence o f hypertension in populations, the C o m m u n i t y Hypertension Evaluation Clinic ( C H E C ) P r o g r a m m e conducted by Stamler et al. (1976) 2 is most comparable to the present study because it involves volunteer subjects and casual sitting pressures performed by trained health personnel. C H E C found 24.7% with diastolic blood pressure levels ~>90mm Hg, 11.6% with diastolic levels >~95 turn H G and 2.6% with diastolic levels >~ 110 m m Hg. In the present study, 29.9% had a diastolic blood pressure 1>90 m m Hg. 10.6% had a diastolic blood pressure ~>95 m m Hg and 3.8% had a diastolic blood pressure ~> 110 m m Hg. There appears to be a larger n u m b e r o f mild hypertensives (>~90 m m Hg) a m o n g Sri Lankan adults when compared to Americans. The prevalence of moderate ( > ~ 9 5 m m H g ) and severe hypertension (~> l l 0 m m Hg) in Sri Lankans is comparable to that o f Americans. The data o f the present study also compares closely to the 22.3% prevalence o f diastolic
Hypertension in Sri Lanka
461
levels >_-90m m Hg and 10.8% prevalence o f diastolic levels />95 m m H g in Milwaukee? However, a study of blood pressure in a Scottish town 4 yielded higher prevalence rates of mild and moderate hypertension. Out o f 3,001 subjects screened in the Scottish T o w n o f Renfrew, 39.8% had diastolic blood pressures/> 90 m m H g and 25.8% had diastolic blood pressures >_-95m m Hg. The prevalence o f hypertension in Sri Lankans (44.3%) in this survey is higher than those reported in some African communities, such as 34% a m o n g persons 45 years old or more in U g a n d a 5 and 20~30% in the inhabitants of Lagos city in Nigeria. 6 Figures 1, 2 and 3 c o m p a r e the prevalence of hypertension o f different grades of severity in Sri Lankans and Black and White Americans. Prevalence of hypertension in Sri Lankans appears to be higher than in white Americans and less than in Black Americans. The stress of living in urban America, a large salt intake and hereditary influences have all been suggested as possible causes for an increased prevalence o f hypertension a m o n g blacks. 7,~ The average daily intake o f salt in Sri Lankans has been reported to be as high as 8.7 grams. 9 There is considerable evidence indicating dietary salt as a major factor in the pathogenesis o f hypertension. 1° The high salt intake m a y be a possible causative factor for the high prevalence of hypertension a m o n g Sri Lankans. Furthermore, if current therapeutic trials show benefit to the health of the c o m m u n i t y from treating 'mild' as well as ' m o d e r a t e ' hypertension, the presence o f a large number of 'mild' hypertensives in the population will have important implications for the resources of the health care system. 500 450 400 350
250
.// 2
/
/ :...'.. ......... . ..... ;;; . . . . . . . . . . . . . "
5o 0 <20
I 20-29
I 3 0 39
<20
21-30
31-40
I 40-49
I 50-54
I 60-64
I ~>65-CHEC program
41-50
51-60
61-70
>71 present study
A g e (years)
Figure 2 Comparison of prevalence of elevated blood pressure at screening (diastolic = 95 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... wlalte male; --- white female).
S. Mendis, P. Ranasinghe and B. D. Dharmasena
462 500 450 400 35O o300
46 25o £3
E 200
Z 150 1O0 0 0
/'"
<20 <20
20-29 21 30
~T. ....................................
30-39 31-40
40 49 41-50
50-54 51 60
J
60 64 ~>65-CHEC program 61 70 >71 present study
A g e (years)
Figure 3 Comparison of prevalence of elevated blood pressure at screening (diastolic = 1 I0 mm Hg). Results of present study compared with community hypertension development program (CHEC). (Key: Sri Lankan male; .... Sri Lankan female; . . . . . black male; black female; .... white male; --- white female).
Acknowledgements W e wish to t h a n k the final year Medical U n d e r g r a d u a t e s o f the F a c u l t y o f Medicine, University o f Peradeniya, Sri L a n k a , w h o participated in the c o n d u c t o f this survey and Mr. Suraweera w h o helped in the analysis o f data. This project was s u p p o r t e d by a g r a n t f r o m the University o f Peradeniya, Sri L a n k a .
References 1. Bibile, S. W., Cullambine, H., Kirthisinghe, C., Watson, R. S. & Wikramanayake, T. (1949). Ceylon Journal of Medical Science, 6, 79-82. 2. Stamler, J., Stamler, R., Riedlinger, W. F., Alegra, G. & Roberts, R. H. (1976). Journal of the American Medical Association, 35, 2299. 3. Itskovitz, H. D., Kocher, M. S., Anderson, A. J. & Rimm, A. A. (1977). Journalofthe American Medical Association, 238, 864. 4. Hawthorne, V. H., Greaves, D. A. & Beevers, D. G. (1974). British Medical Journal, 3, 600-603. 5. Ikeme, A. C. et al. (1973). Bulletin of the Worm Health Organization, 48, 751-753. 6. Johnson, O. T. (1971). British Journal of Preventive and Social Medicine, 25, 26-33. 7. Boyle, E. Jr. (1970). Journal of the American Medical Association, 13, 1637. 8. Stamler, J., Stamler, R. & Pullman, J. N. (1967). Epidemiology of Hypertension, p.122. New York: Grune and Stratton. 9. Pallemulle, L., Mendis, S. & Perera, P. L. P. (1983). Proceedings of the Kandy Society of Medicine, 6, 10. 10. Dehl, L. K. (1972). American Journal of Clinical Nutrition, 25, 23 I.