- Email: [email protected]
Effect of smoking on blood pressure
Effect of smoking on blood pressure Carl C. Seltzer, Ph.D. Boston, hfasa.
The 1971 Public Health Service Report on smoking and health concluded, “Some epidemiological studies have indicated that smokers tend to have lower mean systolic and/or diastolic blood pressure than nonsmokers, while other studies have not found this to be the case.“’ In a separate and more extensive review of blood pressure levels according to smoking habits by Larson and Silvette,2 lower levels of blood pressure among smokers than nonsmokers were indicated in most studies, and ex-smokers tended to have higher blood pressures than current cigarette smokers. Blood pressure differences between smoking and nonsmoking groups have been attributed by some to body weight (adiposity) differentials among the various smoking groups3 Most research on the relationship of cigarette smoking to blood pressure is based on cross-sectional and prevalence data. Longitudinal studies measuring changes in blood pressure over time for subjects with different smoking habits are rare. Even less information is available on blood pressure changes for persons who have recently given up smoking cigarettes. This study will examine the secular changes in systolic and diastolic blood pressure according to smoking habits over an interval of five years in a series of healthy white veterans. Data and methods
The data on which this report is based were derived from a series of 849 adult white male From the Normative Aging Study, Boston Outpatient Clinic, Veterans Administration, and the Department of Nutrition, Harvard School of Public Health, Boeton, Mass. This study supported in part by The Fund for Reeearch and Teaching of the Harvard School of Public Health, and the Council for Tobacco Research-U. S. A. Received for publication July 26, 1973. Reprint requests to: Carl C. Seltzer, Ph.D., Senior Research Associate in Biological Anthropology, Department of Nutrition, Harvard University School of Public Health, 665 Huntington Ave.,, Boston, Maan. 02116.
568
veterans participating in the Normative Aging Study of the Veterans’ Administration Outpatient Clinic in Boston, Mass.-an ongoing prospective study of aging. This is a selected population, since the participants were rigidly screened for an initial high level of health and for a reasonable expectation of geographical stability to assure their lifetime participation in the investigations.’ Special screening for admission into the study was made with respect to blood pressures. Subjects were excluded whose blood pressures in millimeters of mercury were greater than 140 systolic and 90 diastolic. Anthropometric and demographic characteristics such as ethnicity, socioeconomic status, and occupation were not used in qualifying subjects for thestudy. Subjects were examined at entry to the study and approximately five years later. Blood pressure measurements were taken by the examining physicians using standardized mercury sphygmomanometers. Subjects were seated with their arms resting on a desk. Diastolic blood pressures were recorded at the point of disappearance of sounds. Body weight values were obtained during the same examinations as blood pressures. The smoking habits of subjects were obtained at examinations by direct interview. Subjects with mixed forms of smoking (combinations of cigar, pipe, and cigarette), and former or current smokers of cigars or pipe exclusive of cigarettes were excluded from this analysis. Of the total 849 available subjects, 794 had smoking habits which could be classified into one of the following four classes: (11 nonsmokers-subjects with no history of tobacco smoking at entry to study; (2) current cigarette smokers-subjects who gave a history of cigarette smoking at entry and at follow-up period, (3) ex-cigarette smokers-subjects who had a history of cigarette smoking prior to entry May, 1974, Vol. 87, No. 5, pp. 558-564
Effect of smoking on blood pressure Table I. Mean blood pressure (BP> values at admission Nonsmokers No.
to study according
to smoking
Current cigarette smokers
BP (mm Hg)
No.
BP (mm Hg)
class and age
Ex-cigatette smokers No.
BP (mm I&l
Systolic: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
28 35 45 53 26 45 crude standardized*
232
121.9 124.4 123.5 121.8 122.4 123.7 123.0 122.9
50 35 56 40 21 12 214
119.3 119.5 119.0 120.2 120.5 129.0 120.1 120.1
21 36 45 52 47 43 244
125.3 121.6 120.3 124.5 124.1 126.1
73.1 75.8 74.6 76.8 74.6 77.8 75.0 75.0
21 36 46 52 47 43
79.2 76.9 76.9
123.6 123.2
Diastolic: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals, ‘Standardized
crude standardimd*
28 35 45 53 26 45
75.4 78.9 78.1 77.9 76.4 76.6
232
77.4 77.4
on the basis of the age distribution
of current
cigarette
to study but were not smoking at entry; (4) quitters-subjects who were smoking cigarettes at entry to study but who had stopped smoking during follow-up period. The subjects ranged in age from 25 to 64 years at the time of the initial examination, with a mean age for the total series of 45 ,years. Mean ages of subjects within smoking classes indicate that current cigarette smokers and quitters were younger on the average (43 and 42 years, respectively) than nonsmokers and ex-cigarette smokers (46 and 47 years, respectively). The variability in average age among smoking classes requires the age dimension to be included in the analyses of the relationship between smoking class and blood pressure that follow. And since changes in body weight appear to affect blood pressure levels, this variable will also be included in the analysis. The examination of the data will fall into two main parta (1) a cross-sectional view of the characteristics of the subjects at entry into the study according to smoking habits and (2) a longitudinal analysis of the changes in blood pressure for those subjects who modified their American Heart Journal
50 35 56 40 21 12 214
78.6 77.8 75.8
244
7F.7 77.8
smokers.
smoking period.
habits
over
the
five-year
follow-up
Analysis and results Blood pressure and body weight at admission.
Table I gives the mean systolic and diastolic blood pressure values at admission according to smoking habits and age classes. Current cigarette smokers presented a lower over-all mean age-standardized systolic pressure (120.1) than nonsmokers (122.9) and former smokers (123.2). Lower over-all mean diastolic blood pressure for current cigarette smokers (75.0) than for nonsmokers (77.4) and former smokers (77.8) was also recorded In every age class but one the blood pressure values of the cigarette smokers were lower than those of the nonsmokers and former smokers. The body weight values at entry into the study according to smoking class and age are given in Table II. From this table it may be seen that ex-cigarette smokers (those who quit cigarette smoking at some time prior to entry into the study) were by far the heaviest in body weight of the smoking classes. Ex-cigarette smokers with 559
Seltzer
Table II. Mean weight values at admission
to study according
Nonsmokers
to smoking
class and age
Current cigarette smokers
Ex-cigarette smokers
Age group No. -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
crude standardized*
*Standardized
wt. (lb.)
No.
wt. (lb.)
171.0 175.9 171.5 172.0 173.6 168.4 171.8 172.2
50 35 56 40 21 12
171.4 171.9 170.0 172.8 167.0 152.1 170.0 170.0
28 35 45 53 26 45 232
on the basis of age distribution
of current
cigarette
214
wt. (lb.)
21 36 45 52 47 43 244
184.1 175.4 178.5 177.4 173.3 170.1 175.8 178.1
smokers.
Table Ill. Mean
cigarette
No.
blood pressure values (mm. Hg) at, admission smokers and quitters according to age
to study and at follow-up
Continuing cigarette smokers
for continuing
Quitters
Age group No.
Admission
Follow-up
Change
No.
Admission
Follow-up
Change
50 35 56 40 21 12
119.3 119.5 119.0 120.2 120.5 129.0
+0.2 -0.5 -0.2 +2.9 -2.7 -4.5
12%1 120.1
20 26 31 9 11 7 104
119.4 119.9 121.4 125.4 122.2 125.7 121.4 121.8
119.8 122.1 125.9 134.0 126.3 132.6
214
119.4 118.9 118.7 123.1 117.8 124.5 120.0 120.0
122.0 125.8
+0.6 +2.2 +4.5 +8.6 +4.1 +6.9 +3.6* +4.0*
50 35 56 40 21 12
73.1 75.8 74.6 76.8 74.6 77.8
72.5 73.5 75.2 76.2 71.2 72.5
-0.6 -2.3 +0.6 -0.6 -3.4 -5.3
+2.7 +1.1 +1.7 +4.5 +3.7 -0.6
7Co 75.0
74.0 76.2 76.9 74.4 76.2 77.7 75.9 75.6
76.7 77.3 78.6 78.9 79.9 77.1
7T9 73.9
20 26 31 9 11 7 104
7Ko 78.1
+2.1* +2.5*
Systolic BP: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
crude standardizedt
-0.1 -0.1
Diastolic BP: -34 35-39 40-44 45-49 50-54 55+
-
Totals, Totals, *p < 0.05. tStandardized
on the basis of age distribution
an age-standardized were on the average than nonsmokers heavier than current ter group of smokers
560
214
crude standardizedt
of continuing
cigarette
mean value of 178.1 pounds almost six pounds heavier and about eight pounds cigarette smokers. The latwere somewhat more than
-1.1 -1.1
l l
smokers.
two pounds lighter smokers.
in body weight than the non-
Chsnges in blood pressure and body weight at five-year follow-up. There were 104 subjects
class%ed as current
cigarette
smokers
at the
May, 1974, Vol. 87, No. 5
Effect of smoking on blood pressure IV. Mean weight values (lb.1 at admission and quitters according to age
Table
to study and at follow-up for continuing
Continuing cigarette smokers
cigarette
smokers
Quitters
Age group No. -34 35-39 40-44 45-49 50-54 55+ Totals, Totals, *p < 0.05. **p < 0.01. tstandardised
crude standardizedt
on the basis of age distribution
50 35 56 40 21 12 214
Admission
Follow-up
Change
No.
Admission
Follow-up
171.4 171.9 170.0 172.8 167.0 152.1
176.8 176.4 173.2 176.0 165.5 153.8
+5.4** +4.5* +3.2* +3.2* -1.5 +1.7
20 26 31 9 11 7
170.1 176.2 174.8 177.8 171.5 161.0
180.5 182.3 184.7 184.7 177.9 162.3
+10.4* +6.1** +9.9** +6.9** +6.4** +1.3
1G.o 170.0
173.5 173.5
+G**
104
173.2 173.4
181.1 181.4
+G3** +8.0**
of the continuing
cigarette
time of admission to the study who quit smoking at some time during the five-year follow-up period. This group, the quitters, represents those subjects who changed their smoking habits and allows for the evaluation of changes in blood pressure with changes in smoking habits, viewed in light of concomitant body weight changes. Current cigarette smokers at admission to study and at follow-up were used as the standard of comparison for the quitter group. Changes in blood pressure of quitters and continuing cigarette smokers by age. The data for mean systolic and diastolic blood pressure at admission and follow-up for quitters and current cigarette smoker8 are found in Table III. The over-all crude and age-standardized means of these measures at admission and follow-up are given for both groups to indicate the extent of the changes for the total series. With respect to systolic blood pressure, it may be seen that the quitters showed substantial increases in blood pressure for every age class over the follow-up period. The over-all age-standardized increase in systolic blood pressure amounted to 4.0 mm. Hg; this was satistically significant. On the other hand, the continuing cigarette smokers’ systolic blood pressure was unchanged over the same follow-up period. Similarly, the quitters’ diastolic blood pressures significantly increased by an average of 2.5 mm. Hg over the follow-up period, in comAmerican
Heart Journal
+3.5**
Change
smokers.
parison with a modest decline (-1.1 mm. Hg) for the continuing cigarette smokers. Changes in body weight of quitters and continuing cigarette smokers by age. Concomitant with the above changes in blood pressure, both the quitters and the continuing cigarette smokers displayed significant increases in weight over the five-year surveillance period (Table IV). The quitters gained on the average a striking eight pounds; the continuing cigarette smokers also gained weight (3.5 pound&less than one-half as much as the quitters. It is also to be noted that the younger subjects in each smoking category showed the largest weight increases over the follow-up period. Blood pressure changes by weight change groups and smoking classes. A more comprehensive exposition of the relationship between weight change and blood pressure change by smoking class and between systolic and diastolic measures produced the data shown in Table V. Weight change categories from admission to follow-up have been created to indicate appreciable weight loss (-5 to -25 pounds), little or no change (-4 to +4 pounds), moderate weight increase (+5 to +12 pounds), a marked weight gain (+13 to +30 pounds).* The most striking result is that giving up *The extreme ends of the tails of the distribution of weight have not been used so as not to unduly elfect the trends.
changes
561
Seltzer
Table V. Blood pressure changes (mm. Hg) at follow-up for continuing weight changes and standardized for age*
smokers and quitters
according
to
Weigkt change (lb.1 Smoking class No.
-25 to -5
No.
-4 to +4
No.
+5 to +12
No.
+13 to +30
71
27
2.85 4.04
24 32
3.69
71 27
0.73 4.30
24 32
Mean systolic BP changes: Continuing Quitters
smokers
32 13
-4.00
32 13
-3.28 -0.31
1.77
84 27
-1.52
84 27
-2.04 -1.96
2.22
1.50
Mean diastolic BP changes: Continuing Quitters ‘Standardized
smokers
on basis of age distribution
of current
cigarette
smokers.
cigarette smoking (quitters) produced increases in systolic blood pressure even in the group that lost an appreciable amount of weight, from 5 to 25 pounds. The largest increases in systolic blood pressure occurred in those quitters with the largest weight gain, the smallest increase among those who lost the most weight. This finding is not in evidence in the case of the diastolic blood pressure. In this instance, while there were increases in diastolic pressure with increases in weight among the quitters, decreases in pressure occur for those quitters who lost weight. In contrast to the findings for the quitters, Table V indicates that continuing cigarette smokers displayed increases in systolic pressure with increases in weight and decreases with decreases in weight. With respect to diastolic pressure changes among the cigarette smokers, it is significant to note that continuing to smoke over the follow-up period appeared to inhibit an increase in pressure even in those who gained considerable weight. Declines in diastolic pressure accompanied sharp declines in body weight. Since the blood pressure changes in Table V are all age-standardized values, it would appear that controlling for age did not affect the singularity of ‘the pressure changes for the cigarette quitters. While for the continuing cigarette smokers systolic and diastolic changes were quite consistent with the direction of weight changes, in the case of the quitters systolic blood pressure increased with weight loss as well as weight gain. With respect to diastolic pressure,
562
-0.04 3.94
there was virtually no change for the quitters, who lost between five and 25 pounds, compared to a mean decrease of 3.3 mm. Hg for the continuing cigarette smokers with this substantial weight loss. The quitters who gained weight increased their blood pressure more than did the continuing cigarette smokers. Changes to critical blood pressure levels by smoking class. Some of the blood pressure changes seen in the quitters and the continuing cigarette smokers were quite modest and some were fairly substantial. Whether or not they were of biological significance is dif6cult to judge from these over-all values. Some light might be shed on this area by the following analysis. The rigid screening process insured that all subjects at entry into the study had systolic and diastolic pr essures no greater than 140 and 90, respectively. During the follow-up period a number of subjects had increased their blood pressure levels to critical levels of hypertension. Table VI shows the frequency of subjects, for quitters and continuing cigarette smokers, whose blood pressure levels had risen to variously defined critical levels of hypertension. It is clear from this table that the combined effects of giving up cigarettes and the over-all gain in weight produced far greater risks of critical levels of hypertension than continuing to smoke cigarettes. While fewer than one per cent of the continuing cigarette smokers reached systolic blood pressure levels above 160, almost five per cent of the quitters attained this critical level over the follow-up
May, 1974, Vol. 87, No. 5
Effect of smokingon blood pressure
Table VI. Frequency
smokers
of subjects with hypertension,
variously
defined, at follow-up for current
cigarette
and quitters Quitters
Current cigarette smokers No.
%
No.
%
Systolic blood pressure 150+ Systolic blood pressure 160+
6 2
2.8 0.9
9 5
6.7 4.6
Diastolic blood pressure 95+
3
1.4
5
4.6
period. Systolic blood pressure levels of 150 and higher were reached by three per cent of the continuing cigarette smokers, in contrast to about nine per cent for the quitters. Similarly, with respect to diastolic blood pressure levels of 95 and over, almost five per cent of the quitters were found with these critical levels over the follow-up period, as against only 1.4 per cent among the continuing cigarette smokers. It is notable that the greatest increase in pressure to hypertensive levels among the quitters has occurred despite the fact that this group is younger than the continuing smokers. Discussion
The results presented focused primarily on the smoking issue, with age and body weight being controlled in the analysis. The findings of lower mean blood pressure and body weight values at time of admission to the study for the current cigarette smokers, as compared with nonsmokers and former smokers, were consistent with most studies reported in the literature. Investigation of the influence of changes in smoking habits on blood pressure over a five-year period shows clearly that the blood pressure trends of quitters differed from those of continuing cigarette smokers. Recent quitters displayed significant increases in systolic blood pressure in all categories of weight change, whereas the continuing smokers were declining in pressure with losses of weight and showing increases in pressure with gains in weight. In those instances of increasing weight over the surveillance period, greater blood pressure gains were shown by the quitters than the continuing cigarette smokers.
American Heart Journal
With respect to diastolic pressure, the quitters exhibited higher pressure values over the fiveyear interval when associated with weight gain, but there was virtually no change in blood pressure for the quitters who lost substantial amounts of body weight. The continuing cigarette smokers, on the other hand, showed a drop in diastolic pressure with weight loss and essentially no change with weight gain. These data suggest that cigarette smoking tends to have an inhibiting effect on blood pressure, with minimal pressure rises even in instances of substantial weight gains. When this inhibiting effect of cigarette smoking is removed, as in the case of the quitters, sharp rises in blood pressure are evident. This view receives further support from our finding that the risk of attaining hypertensive blood pressure levels over a five year span is far less pronounced among the subjects who continue to smoke than in those who have recently quit the habit. Thus, the effect of smoking remains after controlling for weight changes. It is possible that developing hypertension may be responsible, in some quitters, for decisions to lose weight. In these circumstances, loss of weight may be the reaction to this developing hypertension. However, it would seem likely, over all, that the stopping of cigarette smoking is directly related to increase in blood pressure, even among those who have lost considerable weight. Unfortunately, the data do not allow for the determination of the degree of blood pressure changes according to recentness of giving up cigarettes. Further investigation on this point is necessary.
503
REFERENCES
1. The Health Consequences of Smoking. A Report to the Surgeon General: 1971, U. S. Dept. Health, Education and Welfare, 1971. 2. Larson, P. S., and Silvette, H.: Tobacco: Experimental and clinical studies, Suppl. II, Baltimore. 1971, The Williams & Wilkins Company.
554
3. Reid, D. D., Holland, W. W., and Rose, G. A.: An AngloAmerican cardiovascular comparison, Lancet 2: 1375, 1967. 4. Rose, C., and Bell, B.: Selection of geographical stable subjects in the longitudinal study of aging, J. Am. Geriatr. Sot. 13:143, 1965.
May, 1974, Vol. 87, No. 5
The 1971 Public Health Service Report on smoking and health concluded, “Some epidemiological studies have indicated that smokers tend to have lower mean systolic and/or diastolic blood pressure than nonsmokers, while other studies have not found this to be the case.“’ In a separate and more extensive review of blood pressure levels according to smoking habits by Larson and Silvette,2 lower levels of blood pressure among smokers than nonsmokers were indicated in most studies, and ex-smokers tended to have higher blood pressures than current cigarette smokers. Blood pressure differences between smoking and nonsmoking groups have been attributed by some to body weight (adiposity) differentials among the various smoking groups3 Most research on the relationship of cigarette smoking to blood pressure is based on cross-sectional and prevalence data. Longitudinal studies measuring changes in blood pressure over time for subjects with different smoking habits are rare. Even less information is available on blood pressure changes for persons who have recently given up smoking cigarettes. This study will examine the secular changes in systolic and diastolic blood pressure according to smoking habits over an interval of five years in a series of healthy white veterans. Data and methods
The data on which this report is based were derived from a series of 849 adult white male From the Normative Aging Study, Boston Outpatient Clinic, Veterans Administration, and the Department of Nutrition, Harvard School of Public Health, Boeton, Mass. This study supported in part by The Fund for Reeearch and Teaching of the Harvard School of Public Health, and the Council for Tobacco Research-U. S. A. Received for publication July 26, 1973. Reprint requests to: Carl C. Seltzer, Ph.D., Senior Research Associate in Biological Anthropology, Department of Nutrition, Harvard University School of Public Health, 665 Huntington Ave.,, Boston, Maan. 02116.
568
veterans participating in the Normative Aging Study of the Veterans’ Administration Outpatient Clinic in Boston, Mass.-an ongoing prospective study of aging. This is a selected population, since the participants were rigidly screened for an initial high level of health and for a reasonable expectation of geographical stability to assure their lifetime participation in the investigations.’ Special screening for admission into the study was made with respect to blood pressures. Subjects were excluded whose blood pressures in millimeters of mercury were greater than 140 systolic and 90 diastolic. Anthropometric and demographic characteristics such as ethnicity, socioeconomic status, and occupation were not used in qualifying subjects for thestudy. Subjects were examined at entry to the study and approximately five years later. Blood pressure measurements were taken by the examining physicians using standardized mercury sphygmomanometers. Subjects were seated with their arms resting on a desk. Diastolic blood pressures were recorded at the point of disappearance of sounds. Body weight values were obtained during the same examinations as blood pressures. The smoking habits of subjects were obtained at examinations by direct interview. Subjects with mixed forms of smoking (combinations of cigar, pipe, and cigarette), and former or current smokers of cigars or pipe exclusive of cigarettes were excluded from this analysis. Of the total 849 available subjects, 794 had smoking habits which could be classified into one of the following four classes: (11 nonsmokers-subjects with no history of tobacco smoking at entry to study; (2) current cigarette smokers-subjects who gave a history of cigarette smoking at entry and at follow-up period, (3) ex-cigarette smokers-subjects who had a history of cigarette smoking prior to entry May, 1974, Vol. 87, No. 5, pp. 558-564
Effect of smoking on blood pressure Table I. Mean blood pressure (BP> values at admission Nonsmokers No.
to study according
to smoking
Current cigarette smokers
BP (mm Hg)
No.
BP (mm Hg)
class and age
Ex-cigatette smokers No.
BP (mm I&l
Systolic: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
28 35 45 53 26 45 crude standardized*
232
121.9 124.4 123.5 121.8 122.4 123.7 123.0 122.9
50 35 56 40 21 12 214
119.3 119.5 119.0 120.2 120.5 129.0 120.1 120.1
21 36 45 52 47 43 244
125.3 121.6 120.3 124.5 124.1 126.1
73.1 75.8 74.6 76.8 74.6 77.8 75.0 75.0
21 36 46 52 47 43
79.2 76.9 76.9
123.6 123.2
Diastolic: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals, ‘Standardized
crude standardimd*
28 35 45 53 26 45
75.4 78.9 78.1 77.9 76.4 76.6
232
77.4 77.4
on the basis of the age distribution
of current
cigarette
to study but were not smoking at entry; (4) quitters-subjects who were smoking cigarettes at entry to study but who had stopped smoking during follow-up period. The subjects ranged in age from 25 to 64 years at the time of the initial examination, with a mean age for the total series of 45 ,years. Mean ages of subjects within smoking classes indicate that current cigarette smokers and quitters were younger on the average (43 and 42 years, respectively) than nonsmokers and ex-cigarette smokers (46 and 47 years, respectively). The variability in average age among smoking classes requires the age dimension to be included in the analyses of the relationship between smoking class and blood pressure that follow. And since changes in body weight appear to affect blood pressure levels, this variable will also be included in the analysis. The examination of the data will fall into two main parta (1) a cross-sectional view of the characteristics of the subjects at entry into the study according to smoking habits and (2) a longitudinal analysis of the changes in blood pressure for those subjects who modified their American Heart Journal
50 35 56 40 21 12 214
78.6 77.8 75.8
244
7F.7 77.8
smokers.
smoking period.
habits
over
the
five-year
follow-up
Analysis and results Blood pressure and body weight at admission.
Table I gives the mean systolic and diastolic blood pressure values at admission according to smoking habits and age classes. Current cigarette smokers presented a lower over-all mean age-standardized systolic pressure (120.1) than nonsmokers (122.9) and former smokers (123.2). Lower over-all mean diastolic blood pressure for current cigarette smokers (75.0) than for nonsmokers (77.4) and former smokers (77.8) was also recorded In every age class but one the blood pressure values of the cigarette smokers were lower than those of the nonsmokers and former smokers. The body weight values at entry into the study according to smoking class and age are given in Table II. From this table it may be seen that ex-cigarette smokers (those who quit cigarette smoking at some time prior to entry into the study) were by far the heaviest in body weight of the smoking classes. Ex-cigarette smokers with 559
Seltzer
Table II. Mean weight values at admission
to study according
Nonsmokers
to smoking
class and age
Current cigarette smokers
Ex-cigarette smokers
Age group No. -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
crude standardized*
*Standardized
wt. (lb.)
No.
wt. (lb.)
171.0 175.9 171.5 172.0 173.6 168.4 171.8 172.2
50 35 56 40 21 12
171.4 171.9 170.0 172.8 167.0 152.1 170.0 170.0
28 35 45 53 26 45 232
on the basis of age distribution
of current
cigarette
214
wt. (lb.)
21 36 45 52 47 43 244
184.1 175.4 178.5 177.4 173.3 170.1 175.8 178.1
smokers.
Table Ill. Mean
cigarette
No.
blood pressure values (mm. Hg) at, admission smokers and quitters according to age
to study and at follow-up
Continuing cigarette smokers
for continuing
Quitters
Age group No.
Admission
Follow-up
Change
No.
Admission
Follow-up
Change
50 35 56 40 21 12
119.3 119.5 119.0 120.2 120.5 129.0
+0.2 -0.5 -0.2 +2.9 -2.7 -4.5
12%1 120.1
20 26 31 9 11 7 104
119.4 119.9 121.4 125.4 122.2 125.7 121.4 121.8
119.8 122.1 125.9 134.0 126.3 132.6
214
119.4 118.9 118.7 123.1 117.8 124.5 120.0 120.0
122.0 125.8
+0.6 +2.2 +4.5 +8.6 +4.1 +6.9 +3.6* +4.0*
50 35 56 40 21 12
73.1 75.8 74.6 76.8 74.6 77.8
72.5 73.5 75.2 76.2 71.2 72.5
-0.6 -2.3 +0.6 -0.6 -3.4 -5.3
+2.7 +1.1 +1.7 +4.5 +3.7 -0.6
7Co 75.0
74.0 76.2 76.9 74.4 76.2 77.7 75.9 75.6
76.7 77.3 78.6 78.9 79.9 77.1
7T9 73.9
20 26 31 9 11 7 104
7Ko 78.1
+2.1* +2.5*
Systolic BP: -34 35-39 40-44 45-49 50-54 55+ Totals, Totals,
crude standardizedt
-0.1 -0.1
Diastolic BP: -34 35-39 40-44 45-49 50-54 55+
-
Totals, Totals, *p < 0.05. tStandardized
on the basis of age distribution
an age-standardized were on the average than nonsmokers heavier than current ter group of smokers
560
214
crude standardizedt
of continuing
cigarette
mean value of 178.1 pounds almost six pounds heavier and about eight pounds cigarette smokers. The latwere somewhat more than
-1.1 -1.1
l l
smokers.
two pounds lighter smokers.
in body weight than the non-
Chsnges in blood pressure and body weight at five-year follow-up. There were 104 subjects
class%ed as current
cigarette
smokers
at the
May, 1974, Vol. 87, No. 5
Effect of smoking on blood pressure IV. Mean weight values (lb.1 at admission and quitters according to age
Table
to study and at follow-up for continuing
Continuing cigarette smokers
cigarette
smokers
Quitters
Age group No. -34 35-39 40-44 45-49 50-54 55+ Totals, Totals, *p < 0.05. **p < 0.01. tstandardised
crude standardizedt
on the basis of age distribution
50 35 56 40 21 12 214
Admission
Follow-up
Change
No.
Admission
Follow-up
171.4 171.9 170.0 172.8 167.0 152.1
176.8 176.4 173.2 176.0 165.5 153.8
+5.4** +4.5* +3.2* +3.2* -1.5 +1.7
20 26 31 9 11 7
170.1 176.2 174.8 177.8 171.5 161.0
180.5 182.3 184.7 184.7 177.9 162.3
+10.4* +6.1** +9.9** +6.9** +6.4** +1.3
1G.o 170.0
173.5 173.5
+G**
104
173.2 173.4
181.1 181.4
+G3** +8.0**
of the continuing
cigarette
time of admission to the study who quit smoking at some time during the five-year follow-up period. This group, the quitters, represents those subjects who changed their smoking habits and allows for the evaluation of changes in blood pressure with changes in smoking habits, viewed in light of concomitant body weight changes. Current cigarette smokers at admission to study and at follow-up were used as the standard of comparison for the quitter group. Changes in blood pressure of quitters and continuing cigarette smokers by age. The data for mean systolic and diastolic blood pressure at admission and follow-up for quitters and current cigarette smoker8 are found in Table III. The over-all crude and age-standardized means of these measures at admission and follow-up are given for both groups to indicate the extent of the changes for the total series. With respect to systolic blood pressure, it may be seen that the quitters showed substantial increases in blood pressure for every age class over the follow-up period. The over-all age-standardized increase in systolic blood pressure amounted to 4.0 mm. Hg; this was satistically significant. On the other hand, the continuing cigarette smokers’ systolic blood pressure was unchanged over the same follow-up period. Similarly, the quitters’ diastolic blood pressures significantly increased by an average of 2.5 mm. Hg over the follow-up period, in comAmerican
Heart Journal
+3.5**
Change
smokers.
parison with a modest decline (-1.1 mm. Hg) for the continuing cigarette smokers. Changes in body weight of quitters and continuing cigarette smokers by age. Concomitant with the above changes in blood pressure, both the quitters and the continuing cigarette smokers displayed significant increases in weight over the five-year surveillance period (Table IV). The quitters gained on the average a striking eight pounds; the continuing cigarette smokers also gained weight (3.5 pound&less than one-half as much as the quitters. It is also to be noted that the younger subjects in each smoking category showed the largest weight increases over the follow-up period. Blood pressure changes by weight change groups and smoking classes. A more comprehensive exposition of the relationship between weight change and blood pressure change by smoking class and between systolic and diastolic measures produced the data shown in Table V. Weight change categories from admission to follow-up have been created to indicate appreciable weight loss (-5 to -25 pounds), little or no change (-4 to +4 pounds), moderate weight increase (+5 to +12 pounds), a marked weight gain (+13 to +30 pounds).* The most striking result is that giving up *The extreme ends of the tails of the distribution of weight have not been used so as not to unduly elfect the trends.
changes
561
Seltzer
Table V. Blood pressure changes (mm. Hg) at follow-up for continuing weight changes and standardized for age*
smokers and quitters
according
to
Weigkt change (lb.1 Smoking class No.
-25 to -5
No.
-4 to +4
No.
+5 to +12
No.
+13 to +30
71
27
2.85 4.04
24 32
3.69
71 27
0.73 4.30
24 32
Mean systolic BP changes: Continuing Quitters
smokers
32 13
-4.00
32 13
-3.28 -0.31
1.77
84 27
-1.52
84 27
-2.04 -1.96
2.22
1.50
Mean diastolic BP changes: Continuing Quitters ‘Standardized
smokers
on basis of age distribution
of current
cigarette
smokers.
cigarette smoking (quitters) produced increases in systolic blood pressure even in the group that lost an appreciable amount of weight, from 5 to 25 pounds. The largest increases in systolic blood pressure occurred in those quitters with the largest weight gain, the smallest increase among those who lost the most weight. This finding is not in evidence in the case of the diastolic blood pressure. In this instance, while there were increases in diastolic pressure with increases in weight among the quitters, decreases in pressure occur for those quitters who lost weight. In contrast to the findings for the quitters, Table V indicates that continuing cigarette smokers displayed increases in systolic pressure with increases in weight and decreases with decreases in weight. With respect to diastolic pressure changes among the cigarette smokers, it is significant to note that continuing to smoke over the follow-up period appeared to inhibit an increase in pressure even in those who gained considerable weight. Declines in diastolic pressure accompanied sharp declines in body weight. Since the blood pressure changes in Table V are all age-standardized values, it would appear that controlling for age did not affect the singularity of ‘the pressure changes for the cigarette quitters. While for the continuing cigarette smokers systolic and diastolic changes were quite consistent with the direction of weight changes, in the case of the quitters systolic blood pressure increased with weight loss as well as weight gain. With respect to diastolic pressure,
562
-0.04 3.94
there was virtually no change for the quitters, who lost between five and 25 pounds, compared to a mean decrease of 3.3 mm. Hg for the continuing cigarette smokers with this substantial weight loss. The quitters who gained weight increased their blood pressure more than did the continuing cigarette smokers. Changes to critical blood pressure levels by smoking class. Some of the blood pressure changes seen in the quitters and the continuing cigarette smokers were quite modest and some were fairly substantial. Whether or not they were of biological significance is dif6cult to judge from these over-all values. Some light might be shed on this area by the following analysis. The rigid screening process insured that all subjects at entry into the study had systolic and diastolic pr essures no greater than 140 and 90, respectively. During the follow-up period a number of subjects had increased their blood pressure levels to critical levels of hypertension. Table VI shows the frequency of subjects, for quitters and continuing cigarette smokers, whose blood pressure levels had risen to variously defined critical levels of hypertension. It is clear from this table that the combined effects of giving up cigarettes and the over-all gain in weight produced far greater risks of critical levels of hypertension than continuing to smoke cigarettes. While fewer than one per cent of the continuing cigarette smokers reached systolic blood pressure levels above 160, almost five per cent of the quitters attained this critical level over the follow-up
May, 1974, Vol. 87, No. 5
Effect of smokingon blood pressure
Table VI. Frequency
smokers
of subjects with hypertension,
variously
defined, at follow-up for current
cigarette
and quitters Quitters
Current cigarette smokers No.
%
No.
%
Systolic blood pressure 150+ Systolic blood pressure 160+
6 2
2.8 0.9
9 5
6.7 4.6
Diastolic blood pressure 95+
3
1.4
5
4.6
period. Systolic blood pressure levels of 150 and higher were reached by three per cent of the continuing cigarette smokers, in contrast to about nine per cent for the quitters. Similarly, with respect to diastolic blood pressure levels of 95 and over, almost five per cent of the quitters were found with these critical levels over the follow-up period, as against only 1.4 per cent among the continuing cigarette smokers. It is notable that the greatest increase in pressure to hypertensive levels among the quitters has occurred despite the fact that this group is younger than the continuing smokers. Discussion
The results presented focused primarily on the smoking issue, with age and body weight being controlled in the analysis. The findings of lower mean blood pressure and body weight values at time of admission to the study for the current cigarette smokers, as compared with nonsmokers and former smokers, were consistent with most studies reported in the literature. Investigation of the influence of changes in smoking habits on blood pressure over a five-year period shows clearly that the blood pressure trends of quitters differed from those of continuing cigarette smokers. Recent quitters displayed significant increases in systolic blood pressure in all categories of weight change, whereas the continuing smokers were declining in pressure with losses of weight and showing increases in pressure with gains in weight. In those instances of increasing weight over the surveillance period, greater blood pressure gains were shown by the quitters than the continuing cigarette smokers.
American Heart Journal
With respect to diastolic pressure, the quitters exhibited higher pressure values over the fiveyear interval when associated with weight gain, but there was virtually no change in blood pressure for the quitters who lost substantial amounts of body weight. The continuing cigarette smokers, on the other hand, showed a drop in diastolic pressure with weight loss and essentially no change with weight gain. These data suggest that cigarette smoking tends to have an inhibiting effect on blood pressure, with minimal pressure rises even in instances of substantial weight gains. When this inhibiting effect of cigarette smoking is removed, as in the case of the quitters, sharp rises in blood pressure are evident. This view receives further support from our finding that the risk of attaining hypertensive blood pressure levels over a five year span is far less pronounced among the subjects who continue to smoke than in those who have recently quit the habit. Thus, the effect of smoking remains after controlling for weight changes. It is possible that developing hypertension may be responsible, in some quitters, for decisions to lose weight. In these circumstances, loss of weight may be the reaction to this developing hypertension. However, it would seem likely, over all, that the stopping of cigarette smoking is directly related to increase in blood pressure, even among those who have lost considerable weight. Unfortunately, the data do not allow for the determination of the degree of blood pressure changes according to recentness of giving up cigarettes. Further investigation on this point is necessary.
503
REFERENCES
1. The Health Consequences of Smoking. A Report to the Surgeon General: 1971, U. S. Dept. Health, Education and Welfare, 1971. 2. Larson, P. S., and Silvette, H.: Tobacco: Experimental and clinical studies, Suppl. II, Baltimore. 1971, The Williams & Wilkins Company.
554
3. Reid, D. D., Holland, W. W., and Rose, G. A.: An AngloAmerican cardiovascular comparison, Lancet 2: 1375, 1967. 4. Rose, C., and Bell, B.: Selection of geographical stable subjects in the longitudinal study of aging, J. Am. Geriatr. Sot. 13:143, 1965.
May, 1974, Vol. 87, No. 5