This study included 2,256 randomly selected participants from 6,769 aged 40-69 years persons visiting health promotion and risk factor screening (HP-RFS) service in Hospital for Children Eye ENT and Rehabilitation Services, during June to December 2019. The mean age (SD) of the participants was 51.75 (8.47) years. The visitors were at this specialty hospital for general eye and ENT consultations.
The mean (SD) BMI was 25.29 (3.81) kg/m2 and 26.72 (4.44) kg/m2 for male and female participants respectively (p<0.001). The mean BMI was observed to gradually decrease with advancing age in both male and female participants. The mean waist to height ratio was 0.56 (0.06) and 0.58 (0.08) for male and female (p<0.001). Similarly, Mean Waist circumference was 90.96 (10.32) cm and 88.24 (10.94) cm for male and female respectively (p<0.001).
Table 1: Mean (SD) of different anthropometric measurements according to age and gender
|
Age group
|
Gender
|
|
40-54 years
|
55-69 years
|
p-value
|
Male
|
Female
|
p-value
|
|
Mean
|
SD
|
Mean
|
SD
|
Mean
|
SD
|
Mean
|
SD
|
SBP
|
118.46
|
14.96
|
122.77
|
16.49
|
<0.01
|
121.47
|
15.50
|
118.90
|
15.74
|
<0.01
|
DBP
|
79.21
|
10.74
|
79.39
|
10.25
|
0.69
|
79.98
|
10.67
|
78.69
|
10.43
|
<0.01
|
Weight (KG)
|
65.55
|
10.81
|
61.58
|
11.41
|
<0.01
|
67.41
|
11.15
|
61.32
|
10.48
|
<0.01
|
Height (CM)
|
157.60
|
8.84
|
155.47
|
9.15
|
<0.01
|
163.19
|
7.23
|
151.54
|
6.62
|
<0.01
|
WC (CM)
|
89.51
|
10.38
|
89.40
|
11.36
|
0.83
|
90.96
|
10.32
|
88.24
|
10.94
|
<0.01
|
WHtR
|
0.57
|
0.07
|
0.58
|
0.08
|
0.02
|
0.56
|
0.06
|
0.58
|
0.08
|
<0.01
|
BMI
|
26.41
|
4.08
|
25.50
|
4.41
|
<0.01
|
25.29
|
3.81
|
26.72
|
4.44
|
<0.01
|
Prevalence of Obesity and overweight
The prevalence of obesity (BMI≥ 30kg/m2) and overweight (BMI: 25.0 to 29.9 kg/m2) was 16.09% and 42.20% respectively. Female participants had higher prevalence of obesity (21.4%) than male (9.6%) (p-value<0.001). The observed prevalence of overweight among male and female 42.8% and 41.7% respectively, using BMI, is statistically not significant (p-value = 0.6121). Younger age groups have significantly higher prevalence (p-value <0.001) of overweight and obesity in both genders. Table 2 summarizes obesity and overweight according to gender and age groups. Odds ratio for being obese comparing female to male was 2.58 (95% CI:2.01-3.31), and that of being overweight was 0.95 (95% CI:0.0.81-1.13).
The prevalence of obesity by Waist-to-Height-Ratio was 32.76% which is higher than obesity measured by BMI. Female participants have higher prevalence (40.1%) than male participants (23.8%) and the difference is statistically significant (p-value < 0.001). Age group 40 - 54 had significantly higher prevalence of abdominal obesity among female participants (37.59% vs 44.52%, p=0.0195) which was not different among male participants (23.96% vs 23.66%, p=0.974).
High waist circumference was observed among 66.76% participants, female participants have much higher prevalence (77.46%) than male (53.73%) (p<0.001). Thus, WC detected highest prevalence of obesity compared to other two metrics, the prevalence is not significantly different in between age groups.
Table 2: BMI, WHtR and Waist circumference classification according to age and sex
Characteristic
|
n
|
Body Mass Index (BMI)
|
Waist to Height Ratio (WHtR)
|
Waist Circumference# (CM)
|
≥ 30.0 kg/m2
|
25.0 - 29.9 kg/m2
|
< 25.0 kg/m2
|
> 0.60
|
0.50 - 0.59
|
< 0.50
|
≥ cut off
|
< cut off
|
All
|
|
2,256
|
16.09
|
42.20
|
41.71
|
32.76
|
53.19
|
14.05
|
66.76
|
33.24
|
Male
|
All age
|
1,048
|
9.60
|
42.80
|
47.50
|
23.80
|
60.00
|
16.20
|
53.73
|
46.27
|
|
40-54
|
634
|
10.88
|
47.48
|
41.64
|
23.65
|
60.25
|
16.09
|
55.68
|
44.32
|
|
55-69
|
384
|
7.55
|
35.16
|
57.29
|
23.96
|
59.63
|
16.41
|
50.52
|
49.48
|
Female
|
All age
|
1,238
|
21.40
|
41.70
|
36.90
|
40.10
|
47.60
|
12.30
|
77.46
|
22.54
|
|
40-54
|
782
|
21.74
|
44.37
|
33.89
|
37.59
|
50.00
|
12.40
|
77.75
|
22.25
|
|
55-69
|
456
|
20.83
|
37.06
|
42.10
|
44.52
|
43.42
|
12.06
|
76.97
|
23.06
|
# cut off value of waist circumference for male is 90 cm and for female is 80 cm
Prevalence of Hypertension
Overall prevalence of hypertension and pre hypertension was 40.67% and 36.77% respectively. Male participants had slightly higher prevalence of hypertension (42.72%) than female participants (39.00%). Prevalence, of hypertension for both genders was found to increase as the age group increased. Prevalence of Pre- hypertension was found to be 38.50% and 33.85% among male and female participants. A staggering 81. 50% of male and 74.11% of female participants had either established hypertension or pre hypertension (hypertension suspects) A concerning finding was that among 916 participants with hypertension, 57.4% didn’t know they had raised blood pressure before this study.
Age adjusted odds ratio for being hypertensive for female compared to male was 0.85 (95% CI:0.72-1.02) and sex adjusted odds ratio for being hypertensive was 1.61 (95% CI: 1.35-1.91) for age group 55-69 compared to age group 40-54.
Table 3: Hypertension, sociodemographic variables and risk factors
|
|
Pre HTN
n (%)
|
HTN
n (%)
|
Unadjusted Odds Ratio for HTN (95% CI)
|
Adjusted Odds ratio* for HTN (95% CI)
|
All
|
|
828 (36.77)
|
916 (40.67)
|
|
|
Sex
|
Female
|
434 (35.11)
|
482 (39.00)
|
1
|
1
|
Male
|
394 (38.78)
|
434 (42.72)
|
0.86 (0.88-1.01)
|
0.86(0.72-1.02)
|
Age group
|
40-54
|
544 (38.50)
|
514 (36.38)
|
1
|
1
|
55-69
|
284 (33.85)
|
402 (47.91)
|
1.61 (1.35-1.91)
|
1.61(1.35-1.91)
|
BMI
|
< 25 kg/m2
|
337 (35.93)
|
312 (33.26)
|
1
|
1
|
≥ 25 kg/m2
|
491 (37.37)
|
604 (45.97)
|
1.74 (1.43-2.03)
|
1.89 (1.58-2.26)
|
WHtR
|
< 0.5
|
93 (31.74)
|
83 (28.33)
|
1
|
1
|
≥ 0.5
|
735 (37.52)
|
833 (42.52)
|
1.87 (1.43-2.45)
|
1.92 (1.46-2.52)
|
WC# (CM)
|
< cutoff
|
281 (37.57)
|
235 (31.42)
|
1
|
1
|
≥ cutoff
|
547 (36.37)
|
681 (45.28)
|
1.81 (1.50-2.17)
|
2.02 (1.66-2.45)
|
# cut off value of waist circumference for male is 90 cm and for female is 80 cm
* adjusted odds ratio of age and sex were adjusted for sociodemographic variables (age, sex).
Obesity and Hypertension
Prevalence of hypertension among the participants with BMI≥25kg/m2, WHtR≥0.5 and WC≥ cutoff value was 45.97%, 42.52% and 45.28% respectively. Not surprisingly, higher prevalence of hypertension was found among participants with either overweight or obesity compared to participants with normal weight (P-value <0.001). Age and sex adjusted Odds ratio for being hypertensive among high BMI, Waist to Height Ratio and Waist circumference than normal; were 1.74 (95% CI: 1.43-2.03), 1.87 (95% CI:1.43-2.45) and 1.81 (95% CI:1.50-2.17) respectively indicating waist to height ratio and waist circumference’s ability to better predict hypertension than BMI
Table 4 shows the correlation between BMI, WC, WHtR, BP and Age including level of significance. A strong positive correlation (r=0.682, P<0.01) was found between Waist circumference and BMI. Waist circumference had highest positive correlation (r=0.188, p<0.01) with systolic blood pressure than other two metrices. However, BMI had highest positive correlation (r=214, p<0.01) with hypertension than other metrices. The relationship between all three anthropometric metrices and systolic blood pressure was found higher than with diastolic blood pressure.
Table 4. Correlation between BMI, WHtR, WC, SBP, DBP and Age
|
BMI
|
WC (CM)
|
WHtR
|
SBP
|
DBP
|
Age
|
BMI
|
1
|
0.682**
|
0.770**
|
0.154**
|
0.214**
|
-0.120**
|
WC (CM)
|
0.682**
|
1
|
0.884**
|
0.188**
|
0.192**
|
-0.004
|
WHtR
|
0.770**
|
0.884**
|
1
|
0.168**
|
0.183**
|
0.054*
|
SBP
|
0.154**
|
0.188**
|
0.168**
|
1
|
0.726**
|
0.137**
|
DBP
|
0.214**
|
0.192**
|
0.183**
|
0.726**
|
1
|
-0.007
|
Age
|
-0.120**
|
-0.004
|
0.054*
|
0.137**
|
-.007
|
1
|
Abbreviations: BMI: Body Mass Index; CM: Centimeters; WC: Waist Circumference; WHtR: Waist to Height Ratio.
** Correlation is significant at the 0.01 level (2-tailed).
* Correlation is significant at the 0.05 level (2-tailed).
Receiver Operating Characteristic (ROC) analyses were used to determine the relative ability of the three-obesity metrics to predict HTN as depicted in Fig. 1 and Table 5. The areas under the curve (AUC) were significantly higher than 0.5 for BMI (0.570, 95% CI: 0.548-0.592), WC (0.585, 95% CI: 0.563-0.607) and WHtR (0.586, 95% CI:0.564-0.608). In both gender and all age groups, area under the curve is significantly higher than 0.5 (P<0.01)
Figure 1: Comparison of the ROC curves of WC, WHR and BMI in total participants
Table 5. Sex and Age specific comparisons of the area under Receiver Operating Characteristic (ROC) curves of Body Mass Index (BMI), Waist Circumference (WC) and Waist to Height Ratio (WHtR)
|
|
Area (95% CI) under the curve
|
|
|
BMI
|
WC (CM)
|
WHtR
|
All
|
|
0.593(0.569-0.616)*
|
0.610 (0.586-0.633)*
|
0.602 (0.578-0.625)*
|
Sex
|
Male
|
0.620 (0.585-0.654)*
|
0.620 (0.586-0.655)*
|
0.629 (0.595-0.664)*
|
|
Female
|
0.581 (0.549-0.614)*
|
0.598 (0.566-0.630)*
|
0.590 (0.558-0.623)*
|
Age
|
40-54
|
0.600 (0.570-0.631)*
|
0.606 (0.563-0.625)*
|
0.594 (0.563-0.625)*
|
|
55-69
|
0.610 (0.572-0.648)*
|
0.620 (0.583-0.658)*
|
0.609 (0.572-0.647)*
|
Abbreviations: BMI: Body Mass Index; CM: Centimeters; WC: Waist Circumference; WHtR: Waist to Height Ratio.
* p<0.01