Bone Density Characteristics of Study Subjects


2.5. Research diagram


Postmenopausal women are screened by history taking, physical examination, and basic blood tests.

n = 566


Bone density measurement and blood analysis for genetic analysis


Group

osteoporosis n = 223

Group

no osteoporosis n = 343


Genetic analysis to determine genotypes and alleles of 3 MTHFR gene polymorphisms

rs1801133, LRP5 rs41494349, FTO rs1121980


Goal 1

Determination of genotype polymorphism and comparison of genotype and allele frequencies in the osteoporosis group compared to the non-osteoporosis group

Goal 2

Studying the relationship between gene polymorphisms and bone density and some risk factors for osteoporosis


2.6. Errors and error control.

* Error:

Recall error: the subject answers incorrectly or does not answer.

Systematic error: error in the process of data collection, measurement, data entry and data analysis.

Errors due to measuring instruments, measuring techniques, bone density measurement techniques, DNA extraction techniques, and gene analysis.

* Error control:

- Research subjects were interviewed, clinically examined, had their height and weight measured, and had their blood test results checked by a trained musculoskeletal specialist.

- The research subjects had their bone density measured on the same Explorer machine of Hologic - USA located at the Center for Oncology and Nuclear Medicine - Bach Mai Hospital by trained technicians.

- DNA extraction methods and genotype analysis were performed at the Pathophysiology Department laboratory, Hanoi Medical University by a Pathophysiologist trained in gene analysis. The results were re-examined at the Pathophysiology Department laboratory by a physiologist trained in gene analysis.

- Clean data before entering into computer, detect missing data and unreasonable data, encode before entering.

2.7. Data analysis and processing

Data were entered and checked using REDCap software. Quantitative variables were presented as mean and standard deviation (SD) if normally distributed or median and interquartile range if not normally distributed. Qualitative variables were presented as frequencies and percentages. For continuous variables, comparisons between mean values ​​were performed using Independent samples T test or one-way analysis of variance or Mann


Whitney-U test or Kruskal-Wallis test. For categorical variables, comparison between proportions was performed using Chisquare test or Fisher Exact test. Analysis of the association between genotype and other factors (age, weight, height, BMI, region and education level, history of fracture) with bone density at 3 locations CXĐ, ĐTXĐ, CSTL using univariate and multivariate linear regression analysis.

For each gene, genotypes were coded and entered into hypothetical models for analysis: Dominant model, codominant model, superdominant model, recessive model and additive model. Allele and genotype frequencies were presented in frequencies (%) and Hardy-Weinberg-Equilibrium rule of genotype distribution in the population was tested by Chi-square test or Fisher exact test. Univariate linear regression analysis was applied to assess single-gene effects on bone density at 3 sites. The effects of genetic factors were analyzed in multivariate regression models after adjusting for other risk factors. Subjects with no or one risk allele were used as the reference group.

Unadjusted and adjusted regression coefficients were calculated with 95% confidence intervals. A p-value < 0.05 for both sides was considered statistically significant.

R language software version 3.6.3 was used for statistical analysis and graphing.

2.8. Research ethics

- This study used part of the data in the topic "Determination of polymorphism and susceptibility of genes related to osteoporosis and bone fractures in Vietnamese people" funded by the National Foundation for Science and Technology Development (NAFOSTED) and approved by the ethics committee.


in biomedical research of Dinh Tien Hoang Medical Research Institute No. 01/HĐĐĐ-VNCYHĐTH dated January 27, 2016.

- Research participants are provided with full information about the purpose of the research, the process, sign a consent form to participate in the research, and have the right to withdraw from the research if they do not want to participate.

- Information related to patients is kept confidential.

- Techniques of manipulation on patients are guaranteed to be professional.

- This research is carried out purely for scientific purposes and for no other purpose.


CHAPTER 3. RESEARCH RESULTS


3.1. General characteristics of research subjects

The study was conducted on 566 postmenopausal women screened at the Department of Examination and Department of Musculoskeletal, Bach Mai Hospital.

Table 3.1: General characteristics of research subjects


Characteristic

Study group (n = 566)

a Age (years)

59.6 ± 7.39

a Height (cm)

152.0 ± 5.48

a Weight (kg)

51.29 ± 7.37

a BMI (kg/m2)

22.13 ± 2.70

b BMI grouping

Normal

327 (57.8)

Underweight

40 (7.1)

Overweight and obesity

199 (35.1)

b Place of residence

Countryside

428 (75.6)

Urban

138 (24.4)

b Physical activity (MET-minutes/week)

Not achieved (<600)

242 (42.8)

Pass (≥600)

324 (57.2)

a Obstetric history characteristics

Number of children

3.3 ± 1.5

Age of menopause (years)

48.9 ± 3.8

Number of years to menopause (years)

10.6 ± 8.41

b Characteristics of fracture history, n (%)

Are not

505 (89.2)

Have

61 (10.8)

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Bone Density Characteristics of Study Subjects

a: Variables that follow the normal distribution are represented by mean and standard deviation.

b: Categorical variables are expressed as percentages (numbers).


Comment:


- The average age of the study group was 59.6 years old, average weight was 51.29 kg, average height was 152 cm, average BMI was 22.13 kg/m 2.

- In the BMI subgroup, the normal BMI group accounted for the highest rate of 57.8%, the overweight and obese group accounted for 35.2%, and the underweight group accounted for 7.1%.

Bone density of study subjects

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

0.79

0.66

0.76

CXĐ

Construction

Location

CSTL

g/cm2

- The rate of physical activity reached 51.8%, the average age of menopause was 48.9 years old, the average number of years after menopause was 10.6 years, the average number of children was 3.3 children, 10.8% of postmenopausal women had a history of bone fracture.


Figure 3.1: Bone density characteristics of the study subjects


Comment: Bone density at the proximal femur is highest, while bone density at the femoral neck is lowest.




83,922



91,696



64,311



60,601
































39,399



35,689











16,078



8,304





Osteoporosis rate of study subjects

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

CXĐ

DTXĐ

CSTL

Shared

Location

Osteoporosis

No osteoporosis

Figure 3.2: Distribution of osteoporosis rate of study subjects


Comment:


- Among the three positions of CXĐ, ĐTXĐ, CSTL, the rate of osteoporosis at CSTL is the highest, the rate of osteoporosis at ĐTXĐ is the lowest.

- The overall osteoporosis rate (osteoporosis at any of the three sites: CXĐ, ĐTXĐ, CSTL) is 39.4%.


Table 3.2: General characteristics of study subjects according to osteoporosis and non-osteoporosis subgroups

Grouping


Characteristic

Osteoporosis n=223

No osteoporosis n=343

P

a Age (years)

63.88 (8.00)

56.75 (5.35)

<0.001

a Height (cm)

150.38 (5.76)

153.21 (4.98)

<0.001

a Weight (kg)

47.68 (6.71)

53.63 (6.81)

<0.001

a BMI (kg/m2)

21.05 (2.48)

22.84 (2.61)

<0.001

b BMI grouping



<0.001

Normal

147 (65.9%)

180 (52.5%)


Underweight

29 (13.0%)

11 (3.2%)


Overweight and obesity

47(21.1%)

152 (44.3)


b Place of residence



0.304

Countryside

163 (73.2%)

265 (77.3%)


Urban

60 (26.8%)

78 (22.7%)


b Physical activity (MET- minutes/week)



<0.001

Not achieved (<600)

121(54.3%)

124 (36.2%)


Pass (≥600)

102 (45.7%)

219 (63.8%)


a Obstetric history characteristics




Number of children

3.69 (1.81)

3.01 (1.24)

<0.001

Age of menopause (years)

48.08 (4.21)

49.49 (3.41)

<0.001

Number of years to menopause (years)

15.81 (9.08)

7.27 (5.88)

<0.001

b Characteristics of fracture history



0.019

Are not

190 (85.2%)

315 (91.8%)


Have

33 (14.8%)

28 (8.2%)


a: Variables that follow the normal distribution are represented by the mean and standard deviation, the p value is obtained from the Independent samples T test.

b: Categorical variables are expressed as percentages (numbers), p-values ​​are obtained from the Chisquare test.

Comment:

- There were statistically significant differences in age, height, weight, BMI, BMI subgroup, number of children, age of menopause, number of years of menopause, physical activity and history of fractures in the osteoporosis group compared with the non-osteoporosis group.

- There was no difference in the proportion of postmenopausal women living in urban and rural areas between the osteoporosis and non-osteoporosis groups.

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