In the present study, the author would like to elucidate the association between blood pressure and serum total cholesterol in response to changes in body mass index, which was estimated using a cross-sectional analysis and the relationship between incidence of hypertension and hypercholesterolemia against changes in BMI assessed through a longitudinal analysis of health examination results collected from industrial workers over 11 years (from 2002 through 2012). In the study, a total of 28,249 industrial workers (male subjects: 25,548, and female subjects: 2701 subjects) who aged 30~69 years old, living in Daejeon City, and received regular medical check-up at the health promotion center of a general hospital at east once per year from 2002 to 2012 (over 11 years) were included. In the analysis, the data from 2002 through 2012 was categorized into the Early phase (2002-2005), Middle phase (2006-2009) and Later phase (2010-2012) and then, averages of blood pressure (systolic blood pressure as well as diastolic blood pressure) and serum lipids were stratified by BMI which was obtained from the initial examination results of each individual. In addition, averages of changes in blood pressure as well as serum total cholesterol were analyzed by stratifying with changes in BMI over 10 years (from 2002); annual occurrence rates of high blood pressure, and hypercholesterolemia, stratified per BMI, were further assessed in which patients were in normal ranges of blood pressure and serum total cholesterol. Major findings are as follow.
1. When it comes to blood pressure stratified by BMI, the averages of systolic blood pressure and diastolic blood pressure were higher when patients had elevated BMI in the group of subjects younger than 39 years (P<0.01), the group of subjects in forties (P<0.01), and the group of subjects in fifties (P<0.01) of all phases [i.e., the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)]; yet no difference was noted in the group of subjects who are older than 60 years old.
2. In the average of total cholesterol stratified by BMI, both male and female subjects had significantly higher levels of total cholesterol if they represented elevated BMI in the group of subjects younger than 39 years (P<0.01), and the group of subjects in forties (P<0.01) of all three phases [i.e., the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)]. No difference was found in the groups of subjects in fifties as well as older than 60 years old.
3. Occurrence rates of abnormal systolic blood pressure and diastolic blood pressure, stratified by BMI, were incremented when patients were representing higher BMI in the group of subjects younger than 39 years (P<0.01), the group of subjects in forties (P<0.01), and the group of subjects in fifties (P<0.01) of all phases[i.e., the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)]. To note, the group of subjects older than 60 years old did not showed any association between BMI and blood pressure averages.
4. When it comes to the occurrence rates of abnormal total cholesterol, stratified by BMI, both male and female subject had higher rates in the group of subjects younger than 39 years (P<0.01), and the group of subjects in forties (P<0.01) as the BMI was elevated whilst no significant difference was found in the group of subjects in fifties and the group of subjects older than 60 years
5. Linear regression coefficients of systolic blood pressure and diastolic blood pressure in regards to BMI were all significant in the groups of male subjects younger than 39 years old, male subjects in forties, male subjects in fifties, and male subjects older than 60 years olds of all phases [i.e., the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)] whilst statistically significance was only found in the groups of female subjects younger than 39 years old and female subjects in their forties.
6. Linear regression coefficients of total cholesterol with regards to BMI were all significant in the groups of male subjects younger than 39 years old, male subjects in forties, and male subjects in fifties of all phases [i.e., the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)] whereas statistically significance was demonstrated in the groups of female subjects younger than 39 years old and female subjects in their forties.
7. When it comes to the annual trends of occurrence rates of high blood pressures stratified by BMI, both male and female subjects with normal blood pressure showed increased rates as the BMI was elevating from the low BMI group(less than18.5 kg/m2) through medium(18.5-25.0kg/m2) and high BMI groups(higher than 25.0kg/m2).
8. The annual trends of occurrence rates of hypercholesterolemia, stratified by BMI of patients with normal levels of serum cholesterol, were significantly elevating as patients’ BMI was increased from the low BMI group(less than 18.5 kg/m2) through medium(18.5-25.0kg/m2) and high BMI groups(higher than 25.0kg/m2).
9. The average changes in blood pressure(both systolic blood pressure as well as diastolic blood pressure) in response to changes in BMI over 10 years were significantly elevated in the groups of male subjects with or without obesity as their changes in BMI were more pronounced; in other words, blood pressure changes were more noticeable in which the subjects had increased BMI more than 0.5 kg/m2,compared to those of the other two groups with either reduced BMI(more than 0.5kg/m2 of BMI reduced) or no change in BMI(less than 0.5kg/m2 of BMI changed). In women, however, no specific difference was noted in certain years.
10. The average changes in total cholesterol in response to changes in BMI over 10 years were significantly elevated in both male and female subjects, and the groups of obese and non-obese subjects as the changes in BMI were more pronounced, meaning that total cholesterol changes were more significantly elevated in which the subjects had increased BMI more than 0.5 kg/m2, compared to those of the other two groups with either reduced BMI(more than 0.5kg/m2 of BMI reduced) or no change in BMI(less than 0.5kg/m2 of BMI changed).
Taken together, we analyzed health examination results of industrial workers, collected over 11 years and found that the averages blood pressure and serum total cholesterol were more significantly elevating in the group of subjects with high BMI (higher than 25.0 kg/m2 of BMI) compared to those of the low BMI group (less than 18.5kg/m2) as well as the medium BMI group (18.5-25.0kg/m2) in all three different study phases [the first term(2002-2005), middle term(2006-2009) and last term(2010-2012)]. Similarly, when it comes to the occurrence rates of high blood pressure and hypercholesterolemia, the group of subjects with higher BMI represented elevated risks compared to the groups of subjects with low BMI. In addition, with regards to changes in BMI over 10years, we found that increment of BMI significantly influenced on blood pressure and total cholesterol elevation, demonstrated by they early trends there of.