Zulfiqar Haider ( PMRC Research Centre, Fatima Jinnah Medical College & Ganga Ram Hospital, Lahore. )
Khatoon Akhtar Bano ( PMRC Research Centre, Fatima Jinnah Medical College & Ganga Ram Hospital, Lahore. )
Five hundred patients with essential hypertension of varying severity were reviewed for ponderal index values. They were divided into 4 grades, i.e., mild, moderate, moderately severe and severe according to the level of diastolic blood pressure. The prevalence of obesity in the overall group was 56.2%. The mean ponderal index values in various groups did not show any significant difference. Hypertensives with diabetes mellitus who comprised 23.4% of all the patients did not materially affect the prevalence of obesity amongst hypertensives (JPMA 35 : 354, 1985).
Large scale prospective studies in United States have shown an association between obesity arid elevated blood pressure.1,2 has been observed that obesity is more prevalent in hypertensives, normotensive obese subjects are more likely to develop hypertension and changes in weight are associated with similar directional changes in blood pressure. Impressive reduction in blood pressure in obese hypertensives has also been recorded after weight loss without salt restriction3. These observations show that the control of obesity is one of the potential points of intervention in hypertension.
The prevalence 9f obesity in Pakistani patients with hypertension is not well documented. Also, patients with essential hypertension form a heterogenous group with different-grades of severity and variable response to drugs. Whether patients with mild, moderate or severe grades of essential hypertension are part of a continuous spectrum or have some differences in various characters is not clear.
In this study, the prevalence of obesity in patients with essential hypertension of varying severity attending the ‘Hypertension Clinic’ is reported.
MATERIAL AND METHODS
The records of 500 patients with essential hypertension attending the Hypertension Clinic from 1972 1977 were reviewed for weight and height at the time of registration. A standard size cuff was used to measure the blood pressure in all the patients. Ponderal index was calculated according to the formula :Height (inches)/3 Weight (lbs.). Those with a ponderal index below 12 were designated as obese.
The severity of hypertension was assessed according to the level of diastolic blood pressure.4
According to severity of diastolic blood pressure mild hypertension was present in 294 (58.8%); moderate in 146 (29.2%); moderately severe in 48 (9.6%) and severe in 12 (2.4%) patients.
Table 1 shows the mean values of age (years) and ponderal index in patients with hypertension of varying severity. There was no statistical difference in age and ponderal index in various groups of hypertensives. The prevalence of obesity (ponderal index <12) in different groups of hypertensives was as follows: moderate 58.90%, moderately severe: 47.92%, severe: 33.33%. In the overall group 281 patients (56.2%) were obese. This prevalence rate of obesity amongst hypertensive is statistically significant (S.E. of difference between two proportions).
Table II shows a comparison of ponderal index values in diabetic and non-diabetic hypertensives. The distribution of diabetics in various groups of hypertension was Mild : 96 (32.65%); Moderate: 38 (26.03%); Moderately severe 6 (12.5%) and severe : 2 (16.6%). In the group with mild hypertension, the diabetics had a slightly lower ponderal index (P <0.02) than the non-diabetics. In all other groups, there was no statistical difference in the mean ponderal index values between diabetic and non-diabetic hypertensives.
When the percentage prevalence of obesity in diabetics and non-diabetics was compared in each group, the difference was not significant (Table III).
Present study has the limitation of being entirely hospital based. We used the standard size cuff in all patients which could lead to an over-estimation of blood pressure in obese individuals. However, studies elsewhere have shown that the mean increase in blood pressure in obese individuals using the standard cuff is about 12 mm.5,6 These studies included some very obese individuals and in moderate obesity the elevations were not much.
The range of blood pressure elevation in our patients was large, and the upper limit of mild blood pressure was arbitrarily fixed at 110 mm blood pressure was arbitrarily fixed at 110 mm Hg diastolic. A vast majority of patients with mild hypertension had diastolic blood pressure of 100 mm and above. None of the individuals were grossly obese. It is therefore unlikely that any significant number of obese persons with ‘normal’ blood pressure would have been included. It is, however, desirable in such studies to have large size cuffs available for use, as suggested by Tobian7. However, it confirms the impression that a higher proportion of hypertensives seen in clinical practice are obese. When patients with essential hypertension are divided into groups according to the severity of diastolic hypertension, the mean ponderal indices did not differ significantly in these groups.
Diabetics are generally more obese, and in our group there were 142 (28.4%) diabetics who had associated hypertension. To assess the effect of inclusion of diabetic patients, the mean ponderal index in diabetic and nondiabetic patients in each group were compared. Except in the group with mild hypertension, in which diabetics had a relatively lower ponderal index (P < 0.02), no significant difference was noted in other groups. The prevalence of obesity amongst diabetics and0 non-diabetics in each group showed no significant difference.. Thus, on overall evidence, the inclusion of diabetics did not materially affect the prevalence of obesity amongst the hypertensives.
1. Kannel, W.B., Brand, N., Skinner, J.J.,Dawber, TR. and McNamara, P.M. The relation of adiposity to blood pressure and development of hypertension; the Framingham study. Ann. Intern. Med., 1967;67 : 48.
2. Tyroler, H.A.. Heyden, S. and Hames, C.G. Weight and hypertension; evans county study of blacks and whites, in epidemiology and control of hypertension. Edited by 0. Paul. New York, Stratton Intercontinental, 1975, p. 177.
3. Reisin, E., Abel, R., Modan, M., et al. Effect of weight loss without salt restriction on the reduction of blood pressure in overweight hypertension patients. N. EngI. J. Med., 1978;298 : 1.
4. Haider, Z., Bano, K.A., Zubair, M. and Shahid, M.Hypertension clinic in a general hospital; report on preliminary experience. JPMA., 1977; 27:410.
5. Nielson. P.E. and Janniche, H. The accuracy of auscultatory measurement of arm blood pressure in very obese subjects. Acta Med. Scand., 1974; 195 :403.
6. King, G.E. Errors in clinical measurement of blood pressure in obesity. Clin. Sci., 1967; 32 223.
7. Tobian, L. Hypertension and obesity. N. Engl. J.Med., 1978;298 :46.