We studied 3235 young, healthy participants from 13 May 2019 to 22 February 2020. We excluded 205 volunteers; they were not healthy. (Figure 1)
3.1. Demographic characteristics and Clinical Measurements
Finally, 3,030 volunteers remained (1377 (45.4%) male, 1653 (54.6%) female, mean age 19.5 (± 5) years old, mean BMI 22.3 (± 3.9)) all were in good health. Of 3030 participants, 2732 (90.1 %) were single, 297 of 3030 volunteers (9.8%) were married, only one female was divorced. There was no relationship between these factors and IAD, (P = 0.451). Regarding the weight of participants 1904 out of 3030 (62.8%) had normal weight, and 124 (4.1%) were obese. A total of 115 /3030 persons (3.7%) had a hard-physical occupation (hard duty), 751 out of 3030 volunteers (24.7%) had a moderate duty, and 2164 out of 3030 volunteers
(71.4%) had a low duty (Tables 1, 2, 5).
Table 1: Demographic and Clinical Measurements of the study sample.
|
Systolic BP mmHg
|
Diastolic BP mmHg
|
|
N
|
Mean age/years
|
Mean BMI
|
Right hand
|
Left hand
|
Right hand
|
Left hand
|
Entire Cross-Sectional
|
3030
|
1 9.5 ± 5
|
22.3 ± 3.9
|
116.2 ± 14
|
113.6 ± 13
|
72.9 ± 10
|
72.37 ± 11
|
Right first hand
|
1692
|
20 ± 5
|
22.3 ± 3.8
|
116.4 ± 14
|
113.1 ± 13
|
72.8 ± 11
|
72.12 ± 11
|
Left first hand
|
338
|
20 ± 5
|
22.5 ± 3.7
|
114 ± 13
|
118.2 ± 13
|
73.1 ± 10
|
74.3 ± 10
|
Data are presented as mean ± standard deviation.
Table 2: General characteristics of study participants.
Variables
|
Total N (%)
|
Male N (%)
|
Female N (%)
|
P-Value
|
Age (years)
|
19.56 ± 5.14
|
20.65 ± 5.96
|
18.65 ± 4.13
|
<.001
|
Height (cm)
|
165.83 ± 9.82
|
172.96 ± 7.68
|
159.89 ± 7.08
|
<.001
|
Weight (kg)
|
61.84 ± 13.39
|
68.58 ± 13.37
|
56.23 ± 10.52
|
<.001
|
BMI (kg/m2)
|
22.38 ± 3.84
|
22.87 ± 3.95
|
21.97 ± 3.68
|
<.001
|
Classification of BMI
|
|
|
|
<.001
|
Under weight (BMI >18.5)
|
440 (14.5)
|
169 (38.4)
|
271 (61.6)
|
|
Normal weight (BMI 18.5 – 24.99)
|
1904 (62.83)
|
831 (43.6)
|
1073 (56.3)
|
|
Over weight (BMI 25 – 29.99)
|
562 (18.5)
|
304 (55)
|
258 (45.9)
|
|
Obesity (BMI ≤ 30)
|
124 (4.1)
|
73 (59)
|
51 (41)
|
|
Marital status
|
|
|
|
<.001
|
Single
|
2732 (90.16)
|
1182 (43.26)
|
1550 (56.73)
|
|
Married
|
297 (9.8)
|
195 (65.6)
|
102 (34.3)
|
|
Divorced
|
1 (0)
|
|
1 (0)
|
|
Occupational Status
|
|
|
|
<.001
|
High duty
|
115 (3.7)
|
66 (57)
|
49 (42)
|
|
Moderate duty
|
751 (%24.7)
|
453 (%60.3)
|
298 (39.6)
|
|
Low duty
|
2164 (71.4)
|
858 (39.6)
|
1306(60.35)
|
|
Level of Education
|
|
|
|
<.001
|
Unable to read and write
|
10 (0.33)
|
5 (50)
|
5 (50)
|
|
Able to read and write
|
17 (0.56)
|
7 (41.17)
|
10 (58)
|
|
High school
|
2356 (77.75)
|
1122 (47.6)
|
1234 (52.37)
|
|
Institute Graduate
|
41 (1)
|
26 (63.4)
|
15 (36)
|
|
Under Graduate
|
483 (15.9)
|
158 (32.7)
|
325 (67.2)
|
|
College Graduate
|
119 (3.9)
|
56 (47)
|
63 (53)
|
|
Post Graduate
|
4 (0.13)
|
3 (75)
|
1 (25)
|
|
Data are expressed as mean ± standard deviation, or numbers (%). The p value was derived from independent t-test, chi square, test. BMI = body mass index; underweight if BMI>18.5; normal weight if BMI (18.5-24.99); over weight if BMI 25-29.99); and obesity if BMI ≤30.
3.2. Prevalence of Inter-Arm Blood Pressure (BP) Differences.
Furthermore, 1369 out of 3030 (45.2 %) persons had never previously had their blood pressure measured; a total of 3030 volunteers 1634 had normal BP, 592 had pre-hypertension, but hypertension stage1 was recorded in 420, and hypertension Stage 2 was recorded in 221volunteers. (Table S1&S2)
Regarding the prevalence of inter-arm difference, a total of 163/3030 persons (5.37%) sIABP was equal, a total of 222/3030 persons (7.3%) dIABP was equal, a total of 926/3030 persons (30.7 %) sIAD was 1-4 mmHg, 1149 of 3030 persons (37.88%) sIAD was 5-10 mmHg, and 792 out of 3030 (26.1 %) persons sIAD > 10 mmHg (Table 3). The dIAD > or =10 mmHg was found in 508/1515 persons (33.5%) in the right arm, and 419/1293 persons (32.4%) in the left arm (Table 4). The IAD was greater in males (P < .001) (Table 5).
Table 3: Inter-Arm Blood Pressure (BP) Difference for the Entire Study Population.
|
Systolic BP
|
Diastolic BP
|
Inter-Arm BP Difference
|
All N (%)
|
Right Arm>Left Arm
|
Left Arm>Right Arm
|
All N (%)
|
Right Arm>Left Arm
|
Left
Arm>Right
Arm
|
Entire cross-sectional
|
0 mm/Hg
|
163 (5.3)
|
|
|
222(7.3)
|
|
|
1 mm/Hg
|
303 (10)
|
213
|
90
|
245 (8.1)
|
119
|
126
|
2 mm/Hg
|
230 (7.5)
|
155
|
75
|
265 (8.7)
|
140
|
125
|
3 mm/Hg
|
225 (7.4)
|
138
|
87
|
229.(7.3)
|
116
|
104
|
4 mm/Hg
|
168 (5.5)
|
114
|
54
|
198 (6.5)
|
101
|
97
|
5 mm/Hg
|
352(11.6)
|
226
|
126
|
397 (13.1)
|
221
|
176
|
6 mm/Hg
|
140 (4.6)
|
84
|
56
|
157 (5.1)
|
89
|
68
|
7 mm/Hg
|
153 (5.0)
|
95
|
58
|
136 (4.5)
|
70
|
66
|
8 mm/Hg
|
128 (4.2)
|
78
|
50
|
129 (4.2)
|
81
|
48
|
9 mm/Hg
|
113 (3.7)
|
72
|
41
|
134 (4.5)
|
70
|
64
|
10 mm/Hg
|
263 (8.6)
|
178
|
85
|
252 (8.3)
|
160
|
92
|
Above 10 mm/Hg
|
792(26.1)
|
515
|
277
|
675 (22)
|
348
|
327
|
Total n (%)
|
3030(100)
|
1868(61.65)
|
999(32.9)
|
3030 (100)
|
1515 (50)
|
1293 (42.67)
|
Data are presented as frequency and percentages.
A total of 85/3030 persons (3%) were past smokers, 288 of 3030 persons (9.5%) were current smokers mostly smoking 10 to 20 cigarettes per day, a total of 290/3030 persons (9.6%) were smoking a hookah (Table S3). Nearly all had IAD ranging from 1-20 mmHg, and 30% of their IAD was above 10 mmHg (P < .001) (Table 5). In 2692 volunteers, BP was initially recorded in the dominant hand (right arm), but showed sIAD 5-9 mmHg in 787out of 2692 persons (30.99%), and sIAD> or = 10 mmHg was found in 943 of 2692 volunteers (37.1%) in the right arm. The first measurement was done in 338 left-handed volunteers and showedsIAD 5-9 mmHg in 99 out of 338 volunteers (30%), and sIAD> or = 10 mmHg in 112 out of 338 (34.1%), (P <.001) (Table 4). In addition, the blood oxygen level SPO2 of the all volunteers was normal. There was no association with basic SPO2, (P = 0.20) (Table 5).
Table 4: Inter Arm Systolic and Diastolic Difference.
Clinical variables
Dominant Hand
|
1- 4 mm Hg
N (%)
|
5 – 9 mm Hg
N (%)
|
10 – 14mm Hg
N (%)
|
15–19mm Hg
N (%)
|
≥ 20 mm Hg
N (%)
|
P value
|
Systolic inter-arm
Difference (sIAD)
|
|
Right first hand,
Right hand was dominant (n=2692)
|
809 (32.6)
|
787 (30.9)
|
490 (19.2)
|
196 (7.7)
|
257 (10.1)
|
< .001
|
Left first hand,
Left hand was dominant (n=338)
|
117 (35.6)
|
99 (30)
|
58 (18)
|
26 (7.9)
|
28 (8.5)
|
|
Diastolic inter-arm
Difference (dIAD)
|
|
Right hand (n=1515)
|
476 (31.4)
|
531 (35.05)
|
302 (19.9)
|
116 (7.6)
|
90 (5.9)
|
< .001
|
Left hand (n=1293)
|
452 (34.9)
|
422 (32.63)
|
232 (17.9)
|
106 (8.2)
|
81 (6.2)
|
|
Association was analysed by chi square, test. P ≤.05 is considered as statistically significant. And excluded (n=153) (5.68%) From right first hand and (n=10) (2.9%) from left hand first in this table because there is no difference between systolic right and left arm BP measurements, and excluded (n=222) (7.3%) of the study sample in this table because there is no difference between diastolic right and left arm BP measurements.
On the other hand, the height of participants had an effect on IAD (P =.041), and the residential area had a significant effect on IAD; urban participants had more inter-arm difference than rural area participants, (P =.002) (Table 5). The blood group has no effect on inter-arm difference, (P = 0.65) (Table 5); a total of 440/3030 volunteers (14.5 %) were under weight, 558 of 3030 volunteers (18.4%) were overweight. The IAD of overweight persons showed that 180 of 558 volunteers (32.2%) had IAD; 123 had IAD approximately 5-10 mmHg, and 57 had > 10 mmHg, (P = .046). In addition, 124 of 3030 volunteers (4.1%) were obese, just 30 of 124 (24%) had IAD; 18 had IAD approximately 5-10 mmHg, and 12 had >10 mmHg, (P =.04) (Table S4). The heart rate of 985 of 3030 volunteers was above 90 bpm, and 234 of 985 had IAD; in 162 (% 69.2) were between 5-10 mmHg, in 72 (%30.76) were >10 mmHg, (P =.001) (Table S5).
Table 5: Inter Arm Systolic Difference. (N=2867).
Clinical variables
|
1 – 4 mm Hg
N (%)
|
5 – 10 mm Hg
N (%)
|
Above 10 mm Hg
N (%)
|
P value
|
Age of participant by years
|
|
|
|
0.467
|
Age below 25 years (n=2543)
|
830 (32.6)
|
1018 (40)
|
695 (27.3)
|
|
Age above 25 years (n=324)
|
96 (29)
|
131 (40.4)
|
97 (30)
|
|
Weight of participant by (kg)
|
|
|
|
0.057
|
Weight below 55 kg (n=1052)
|
331 (31.4)
|
403 (38.3)
|
318 (30.2)
|
|
Weight above 55 kg (n=1815)
|
595 (32.7)
|
746 (41.1)
|
474 (26.1)
|
|
Height of participant by (cm)
|
|
|
|
0.041
|
Height below 160 cm (n=1059)
|
323 (30.5)
|
415 (39.2)
|
321 (30.3)
|
|
Height above 160 cm (n=1808)
|
603 (33.3)
|
734 (40.6)
|
471 (26)
|
|
Residential area
|
|
|
|
0.002
|
Rural (n=236)
|
75 (31.7)
|
113 (47.9)
|
48 (20)
|
|
Suburban (n=1186)
|
400 (33.7)
|
484 (40.8)
|
302 (25.4)
|
|
Urban (n=1445)
|
451 (31.2)
|
552 (38.2)
|
442 (30.6)
|
|
Level of Education
|
|
|
|
0.055
|
Unable to read and write (n=9)
|
4 (44)
|
3 (33)
|
2 (22)
|
|
Able to read and write (n=14)
|
3 (21)
|
6 (43)
|
5 (36)
|
|
High school (n=2231)
|
734 (32.9)
|
877 (39.3)
|
620 (27.8)
|
|
Institute graduate (n=39)
|
19 (48)
|
12 (30)
|
8 (20.5)
|
|
Undergraduate (n=461)
|
141 (30.6)
|
207 (44.9)
|
113 (24.5)
|
|
College graduate (n=110)
|
24 (22)
|
43 (39)
|
43 (39)
|
|
Postgraduate (n=3)
|
1 (33)
|
1 (33)
|
1 (33)
|
|
Blood group (n=2762)
|
|
|
|
0.635
|
A (n=717)
|
238(33.2)
|
277 (38.6)
|
202 (28.5)
|
|
B (n=420)
|
147 (35)
|
161 (38.3)
|
112 (26.6)
|
|
AB (n=172)
|
50 (29)
|
71 (42)
|
51 (29)
|
|
O (n=1000)
|
310 (31)
|
416 (41.6)
|
274 (27.)
|
|
Unknown blood group (n=453)
|
158 (34.8)
|
172 (37.9)
|
123 (27.1)
|
|
Gender
|
|
|
|
< .001
|
Male (n=1284)
|
453 (35.2)
|
521 (40.5)
|
310 (24.1)
|
|
Female (n=1583)
|
473 (29.8)
|
628 (39.6)
|
482 (30.4)
|
|
Marital status
|
|
|
|
.451
|
Single (n=2590)
|
848 (32.7)
|
1030 (39.7)
|
712 (27.5)
|
|
Married (n=277)
|
78 (28.1)
|
117 (42.2)
|
80 (28.9)
|
|
Past smoking
|
|
|
|
< .001
|
Yes (n=78)
|
26 (33)
|
27 (34)
|
25 (32)
|
|
No (n=2789)
|
900 (32.2)
|
1122 (40.22)
|
767 (27.5)
|
|
Current smoking
|
|
|
|
< .001
|
Yes (n=274)
|
84 (30.6)
|
104 (37.9)
|
86 (31)
|
|
No (n=2593)
|
842 (32.4)
|
1045 (40.30)
|
706 (27.2)
|
|
Smoking hookah
|
|
|
|
< .001
|
Yes (n=273)
|
88 (32.2)
|
113 (41.3)
|
72 (26.3)
|
|
No (n=2594)
|
838 (32.3)
|
1036 (39.9)
|
720 (27.7)
|
|
First time BP measurement
|
|
|
|
.187
|
Yes (n=1578)
|
487 (30.8)
|
648 (41)
|
443 (28)
|
|
No (n=1289)
|
439 (34)
|
501 (38.8)
|
349 (27)
|
|
SPO2%
|
|
|
|
.200
|
SPO2 between (91-95%), (n=131)
|
33 (25)
|
59 (45)
|
39 (29)
|
|
SPO2 between (96-99%), (n=2736)
|
893 (32.6)
|
1090 (39.83)
|
753 (27.5)
|
|
Data are expressed as frequency and percentage, or numbers (%). The P value was derived from, chi square test. P ≤ .05 is considered a statistically significant. Abbreviations: Kg = kilogram, Cm= centimetre. Blood group (A, B, AB, O) both positive, SPO2 = peripheral capillary oxygen saturation.