Synopsis of doctoral dissertation: Study on bone mineral density and fracture risk factors in menopausal women in Rach Gia City, Kien Giang province

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Two following objectives: To survey the BMD with DXA method and determine the rate of osteoporosis in the community, along with factors related to osteoporosis in postmenopausal women; To assess the fracture risk in the community through two Garvan and FRAX models.

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Nội dung Text: Synopsis of doctoral dissertation: Study on bone mineral density and fracture risk factors in menopausal women in Rach Gia City, Kien Giang province

THE MINISTRY OF EDUCATION AND TRAINING THE MINISTRY OF NATIONAL DEFENSE VIETNAM MILITARY MEDICAL UNIVERSITY  THAI VIET TANG THE STUDY ON BONE MINERAL DENSITY AND RISK FACTORS OF FRACTURE IN POSTMENOPAUSAL WOMEN IN RACH GIA CITY, KIEN GIANG PROVINCE Specialist: Internal Medicine Code: 9720107 SYNOPSIS OF DOCTORAL DISSERTATION HA NOI – 2019
The work has been successfully completed at Vietnam Military Medical University Science Instructors: Assoc. Prof., Ph.D. Đoàn Văn Đệ Opponent 1: Opponent 2: Opponent 3: The thesis has been defended at Institutelevel Thesis Evaluation Council at Military Medical University............ (hour),...../...../..... (date) This thesis may be found at: Vietnamese National Library Library of Military Medical University
1 INTRODUCTION THE URGENT NATURE OF THE THESIS Osteoporosis is defined as a pathology characterized by reduced bone strength and an increased risk of bone fractures. Bone strength is related to two main factors which are bone mineral density (BMD) and bone structure. In postmenopausal women and men over 50, BMD is reduced by age, and the structure of the bone is degraded. The reduction of BMD and bone structure degradation make the bone weak and easily broken when impacted with a small force (such as sneezing). Therefore, fractures are a consequence of osteoporosis. Osteoporosis bone fracture is a major medical problem in the elderly. Worldwide, there are more than 8.9 million people with bone fracture every year; in which women are the majority (61%). Bone fractures, especially femoral fracture, increase the risk of mortality. The patients after bone fractures have a poor quality of life and are unable to walk normally. Bone fracture is also a global economic burden, which the annual cost associated with treatment in the United States is up to 1020 billion USD, 2.7 billion EUR in the UK and 7.5 USD in Australia. Patients with bone fracture, especially the femoral neck fracture suffer from complications such as pain, disability and 1220% of mortality in the first year. The survivors are also greatly reduced the quality of life. Currently, there are many methods of diagnosing osteoporosis, in which bone density measurement with DXA method has considered as a gold standard. Individuals whose BMD decline more than 2.5 in standard deviations in comparison with the average value
2 at the age of 2030 are diagnosed with osteoporosis. Patients diagnosed with osteoporosis are indicated for treatment. In addition, patients with a history of bone fractures who have not had osteoporosis are also indicated for treatment. But osteoporosis only partially explains the total number of fractures. Indeed, 55% of women suffering a fracture and 70% of men suffering from fracture, but they do not have osteoporosis. Therefore, osteoporosis only explains about 45% in women and 30% in men having fractures. Many studies around the world have shown that in addition to osteoporosis (or reduction of BMD), other factors also associated with fractures: old age, women, smoking, excessive alcohol use, weight loss., reduced height, history of fractures, long term corticosteroid use, rheumatoid arthritis, secondary osteoporosis, and falls. Therefore, besides BMD, there are 12 other factors that can help assess an individual's risk of bone fracture. For 10 years, there have been some prognostic models developed to assess the risk of fracture. Two popular models are Garvan Fracture Risk Calculator (Garvan) and FRAX. Garvan model uses 5 risk factors (age, BMD, weight loss, history of fractures, and falls); FRAX models use 12 risk factors which are mentioned above. Garvan and FRAX models use risk factors to predict fracture risk for 10 years. According to the recommendation of American National Osteoporosis Foundation (NOF) and International Osteoporosis Foundation (IOF), individuals at risk of fracture above 20% should be indicated for treatment. Two models Garvan and FRAX have been developed and applied in identifying individuals at high risk for treatment and prevention.
3 In Vietnam, there have been a number of studies on osteoporosis in specific patient groups, while the study in the population is still limited. In addition, there have been no studies assessing the risk of bone fracture in the community, and comparing the prognostic value of Garvan and FRAX. Therefore, we carried out the topic "Study on bone mineral density and fracture risk factors in menopausal women in Rach Gia City, Kien Giang province" with two following objectives: + To survey the BMD with DXA method and determine the rate of osteoporosis in the community, along with factors related to osteoporosis in postmenopausal women; + To assess the fracture risk in the community through two Garvan and FRAX models. The study also compared the prognostic value of two Garvan and FRAX models and compared with the recommended treatment indications and current treatment guidelines. NEW CONTRIBUTION FROM THE THESIS + Determine the prevalence of osteoporosis in the community. An important result and contribution of the thesis is the osteoporosis scale in the community in Rach Gia City (Kien Giang). The study indicates that 45% of postmenopausal women have osteoporosis (osteoporosis, 11.2%) or bone loss (osteopenia, 34%). + Determining risk factors related to osteoporosis. The study found that the following factors are related to osteoporosis: elderly, age with the first period above 15, weight loss, and infertility. + The correlation coefficient of prognostic value between Garvan and FRAX models is r = 0.7. This result means that the
4 prognostic value of FRAX model explains 49% of the difference in the prognostic value of the Garvan model. This result shows that two Garvan and FRAX models have relatively high similarity. + Based on the standard of bone fracture risk ≥20%, Garvan model predicted that 59.2% (122 over 206) had a high risk of fracture. FRAX model predicted only 7.3% at high risk (15 over 206). + In the group of osteoporosis, Garvan model predicted 100% (23/23) with a high risk of fracture; FRAX models predicted only 60.9% (14/23). In the group with a history of fractures, the Garvan model has 90% prognosis of high risk (27/30), but the FRAX model proposes only 30% (9/30). These results show that the Garvan model is more relevant to clinical reality than the FRAX model. THESIS OUTLINE The thesis covers 107 pages, including: Preamle: 2 pages Overview: 33 pages Materials and method:13 pages Outcome:28 pages Discussion:28 pages Conclusion: 2 pages Recommendation: 1 page The thesis consists of 42 tables, 6 charts, 9 figures and 129 references (including: 11 references in Vietnamese, 118 references in English). CHAPTER 1. OVERVIEW
5 Bone biology Bone is made up of two main types of tissue: inorganic and organic. Inorganic ingredients account for 70% while organic ingredients contribute 22% of bone weight. The main inorganic component is calcium phosphate hydroxyapatite. Organic ingredients are mainly collagen type I, accounting for about 85%, and non collagen proteins (about 15%) such as osteocalcin, osteopontin, sialoprotein, glycoprotein, proteoglycan, and glaprotein. Bone is a dynamic tissue created from three main cell groups: osteoblast, osteoclast, and osteocyte. The two main cells playing an important role in bone modeling and remodeling are osteoblast and osteoclast. These two types of cells work together and depend on each other, not independently. Osteoblast and osteoclast form a temporary structure called Basic Multicellular Unit (BMU). Each BMU is about 12 mm long and 0.2 to 0.4 mm wide. In normal conditions, osteoblasts and osteoclasts smoothly work together in BMU. When operating normally, the bone mass excreted is equal to the bone mass produced. However, in postmenopausal women and older people, osteoclasts are more active than osteoblasts, which lead to bone loss. Bone loss leads to a decrease in bone strength and an increased risk of bone fractures. Therefore, on the biological perspective, osteoporosis can be considered as a consequence of an imbalance between osteoblasts and osteoclasts. Osteoporosis Osteoporosis is a disease whose two main characteristics are reduced bone strength and degraded bone structure, leading to an increased risk of bone fractures. Bone strength is primarily assessed
6 by bone mineral density (abbreviated as BMD). Low BMD is a risk factor for bone fractures. In 1994, the World Health Organization (WHO) defined Osteoporosis as a disease characterized by reducing bone mass, damaging the subtle structure of bone, resulting in bone weakness and consequently increased risk of fractures. Osteoporosis is therefore diagnosed by measurement of BMD. As recommended by the World Health Organization, when BMD drops more than 2.5 standard deviations from the age of 2030 it is diagnosed with osteoporosis. In Vietnam, there have been several studies in the past few years on osteoporosis scale in the population. A community study in HCMC found that the rate of osteoporosis in women over 60 was about 29%. However, a hospital study in Hanoi found that nearly 60% of patients were diagnosed. Bone fractures are a consequence of osteoporosis. Worldwide, osteoporosis causes fractures every year at least 8.9 million people. In 2010, 158 million people broke their bones, expected to double in 2040. In Asia, it estimates the risk of neck femoral will increase 2.28 times. Costs for treatment of fracture rise billions of dollars each year. Risk factors for osteoporosis Many clinical epidemiological studies in the world and in Vietnam have identified a number of risk factors related to osteoporosis. These factors can be divided into two groups: modifiable and nonmodifiable risk factors. Modifiable factors include lifestyle (smoking, excessive alcohol), poor healthy diet, lack of exercise, reducing sex hormones (estrogen, testosterone), weight loss, dietary intake of low calcium,
7 vitamin D deficiency, falls, and poor health. Nonmodifiable factors include elderly, female, hereditary, history of individual fractures, and family history of fractures. Risk factor for fracture All of the risk factors for osteoporosis listed above are also risk factors for fracture. In addition, the reduction of bone density or osteoporosis is a considerable risk factor. The above factors affect the risk of fracture. Therefore, patients who pose more risk factors will face a greater risk of bone fracture. Prognosis model Although BMD is the most important risk factor for bone fractures, BMD only identifies 55% of women and 25% of men with broken bones. Therefore, the new trend in osteoporosis is to build prognostic models for predicting (prognosis) fractures in 10 years based on each individual's risk factors. Currently, there are two main prognostic models: FRAX and Garvan. FRAX model uses 12 risk factors, Garvan model uses 5 risk factors. Risk factors of FRAX include gender, age, history of bone fracture, weight, height, femoral neck bone density, family history of fracture, smoking, alcohol use, corticosteroid use, rheumatoid arthritis, and secondary osteoporosis. Risk factors in the Garvan model include gender, age, history of fractures, history of falls, and femoral neck bone density. However, assessing the correlation between these two models is still small, and not yet systematic. The study presented in this thesis is designed to provide scientific answers to the following questions: + How many postmenopausal subjects have osteoporosis in the
8 community in Kien Giang; and which factors are related to osteoporosis? + What is the scale of fracture in the community through FRAX and Garvan models? + Consistency between high fracture risk (through FRAX and Garvan models) and treatment indication? STUDY METHOD The study was conducted in the community of Rach Gia City, Kien Giang Province. The study duration was from November 2012 to December 2015. The study was designed according to the cross sectional model. Study subjects: including 206 menopausal women living in Rach Gia City, Kien Giang province, agreeing to participate in the study. Subjects of the study are invited from women's associations and elderly associations. The subjects were explained about the objectives and research process and agreed to participate. They were interviewed at the clinic of Kien Giang General Hospital and Van Phuoc Clinic (Can Tho). Measurement of BMD: each subject was measured the bone density at femoral neck using DXA device labeled Osteocore Station Mobile (MEDII INK, France) at Van Phuoc clinic (Can Tho). The value of the BMD was converted to the T index. Based on the scan results, each woman was classified into one of three groups: normal (Tscore higher than 1), osteopenia (Tscore in 1 to 2.5), and osteoporosis (Tscore is equal to or lower than 2.5).
9 Data collection: Each individual provides information related to anthropology, history of fractures, history of reproduction, lifestyle, weight, and height. Body mass index (BMI) is calculated from weight and height and divided into 3 groups: underweight (BMI
10 STUDY RESULTS The study was conducted on 206 postmenopausal women. The median age of the study subjects was 66 (the minimum value was 48 and the maximum was 85 years old). Among 206 subjects, 46% (n=94) were overweight and 2.4% (n = 5) were underweight. Results of analysis of Tindex showed that: 113 (55%) had normal BMD; 70 (34%) osteopenia, and 23 (11.2%) osteoporosis. The risk factors for osteoporosis are reported in Table 1 below: Risk factors for osteoporosos Risk factors OR 95%CI P Age (+1) 1,15 1,07 – 1,23
11 interval from 1.07 to 1.23). A history of fractures in the family has the greatest impact on the risk of fracture. Among 206 subjects, there were 30 subjects with a history of fractures. Prevalence of patients with history of fracture was 14.6% (confidence interval 95% : from 10.4% to 20%). Univariate analysis showed that the factors related to a history of fracture (statistically significant) are osteoporosis, infertility, a history of falls, and a history of fractures in the family. Table 3.27. The correlation between the history of fractures and osteoporosis History of fracture Non fracture before Osteoporosis OR, p Percentage classification Quantity Quantity Percentage % % Osteoporosis 10,0 12 40,0 11 6,25 (n= 23) (3,86 – 25,9) Non osteoporosis P
12 Table 3.31. The correlation between history of bone fractures and no birth History of fracture Non fracture before Status of OR, p Quantit Percentage Percentage childbirth Quantity y % % No birth 7 23,3 14 8,0 OR=3,52 (n= 21) (1,269,8) Giving birth 23 76,7 162 92,0 p
13 Table 3.35. The correlation between fracture and family history of fracture History of History of fracture History of nonfracture OR, p fractures in family Quantity Percentage % Quantity Percentage % With history of fracture in 10 33,3 12 6,8 OR=6,83 family (n=22) (2,4918,7) No fracture in P=0,001 family 20 66,7 164 93,2 (n=184) Total (n=206) 30 100 176 100 However, the analysis of multivariate logistic regression shows that after adjusting for all factors in the model, only osteoporosis is an independent factor. Accordingly, the subjects with osteoporosis had an odd ratio of 6.83 (95% in confidence interval from 1.71 to 23.0).
14 Table 3.36. Multivariate regression analysis between history of fractures and risk factors. Factors OR 95%CI P Age ≥ 60 2,85 0,2927,56 0,37 BMI 10 years 0,46 0,121,74 0,26 History of falls 1,12 0,433,72 0,85 Family history of fractures 2,48 0,8010,74 0,19 Correlation coefficients r=0,70; p
15 Table 3.37. Predicting the risk of femoral neck fracture by age group Frax Model Garvan Model Age group Low risk High risk Low risk High risk (n=206) n (%) n (%) n (%) n (%)
16 Table 3.41. Comparison between the indications for treatment of osteoporosis and high risk based on the prognostic value of femoral fracture. Prognostic value Total Osteoporosis of femoral p (n = 206) (n = 23) fracture. FRAX ≥ 3% 15 (7,3%) 14 (60,9%) p
17 DISCUSSION Osteoporosis and fracture consequences are the public health burden in the community, especially in menopausal women and elderly men. Osteoporosis is a "silent" disease that has no specific symptoms, so identifying highrisk subjects is a difficult fact in clinical practice. To identify highrisk subjects, understanding the correlation between risk factors and osteoporosis (and fractures) is important. Currently, in the specialty of osteoporosis there are two common models, FRAX and Garvan, which can be used to assess an individual's fracture risk based on risk factors, and thereby identify the objects need to be intervened. However, the studies on the similarity between the two models, and the similarity between prognostic value and treatment indications in Vietnam are still very small. This study was conducted on 206 menopausal women which provided 4 new following information: + The rate of osteoporosis and osteopenia in menopausal women was about 45%; + Risk factors related to osteoporosis include elderly, low BMI, infertility, and a history of fractures in the family; + However, when analyzing with the history of fracture, only osteoporosis (low bone density) was an independent risk factor; + Garvan model identified nearly 60% of subjects with high fracture risk. Garvan model has prognostic value consistent with clinical treatment indications than the FRAX model. The new information from this study represents a contribution to Vietnamese medical literature in the management, treatment, and prevention of osteoporosis at the community level.
18 Our study focused on postmenopausal women (with an average age of 66.8). We chose female subjects because women are more likely to have osteoporosis and fractures than men. In this group, we found 11% of women are in osteoporosis status (Tscore is equal to or less than 2.5). The rate of osteoporosis in this study is somewhat different but is in the average range in comparison to previous studies. In a study of 504 women in Hanoi, Dang Hong Hoa et al. (2007) [3] estimated that 9.3% of women with osteoporosis. A larger study (n = 2232) also on women in Hanoi in 2004 showed that the rate of osteoporosis was 15.4% [2]. In Ho Chi Minh City, the study by Ho Pham Shu Lan et al [4] on 970 postmenopausal women randomly selected in the community showed osteoporosis rate of 29%. In addition, the study of 988 women in Hanoi (in hospital samples) detected 58.4% of osteoporosis [79]. In summary, the abovementioned studies indicate that the extent of osteoporosis in the community can range from 9% to 29%, depending on age and method of measurement. Our study estimates that the rate of osteoporosis was 11.2%, which is lower in comparison with the studies recently reviewed. The difference in the rate of osteoporosis between studies has many causes. The studies were based on the sample, and the sample was selected within the community, so sample fluctuations in estimating proportions are inevitable. In our study, although the average rate was 11.2%, the confidence interval was 95% which ranged from 7% to 16%. It is possible that the subjects in this study were not highly represented in the community, because they were recruited from community organizations (Women's Union, Elderly