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C. Research Variables
1. Definition of Variables
The Consensus Development Conference statement in 1993 defined osteoporosis as a disease characterized by low bone mass and
micro architectural deterioration of bone tissue, leading to an enhanced bone fragility and a consequent increase in fracture risk Meyer et al.,
2000. In 1994, WHO established BMD measurement criteria allowing the diagnosis of osteoporosis before incident fractures Willig et al., 2001.
This definition is based on the major risk factor of reduced bone strength or density and includes those individuals who are at a high risk but without
fractures. Despite the use of bone mass definition, it is important to realize that bone density is a single risk factor and measured at a single point of
time. Other important risk factors include age, life expectancy, bone loss and bone turnover. In 2000, NIH of the United States also defined
osteoporosis as a disease of deteriorating bone strength that leads to increasing risks for bone fracture. Bone strength
by NIH‟s definition is composed of two major indexes of bone density and bone quality.
2. Independent Variables
a. Physical Activity
Physical activity level is categorized as mild, moderate or vigorous. Mild exercise minimal effort such as yoga, archery, fishing
from riverbank, bowling, horseshoes, golf, snowmobiling and easy walking. Moderate exercise not exhausting such as fast walking,
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baseball, tennis, easy bicycling, volleyball, badminton, easy swimming, alpine skiing and popular or folk dancing. Strenuous exercise heart
beats rapidly such as running, jogging, hockey, football, soccer, squash, basketball, cross country skiing, judo, roller skating, vigorous
swimming and vigorous long distance bicycling 5 times or more per week.
b. Age
Older people are classified into three sub-populations that commonly referred to as the young old of 55-70 years, the old of 71-84
years and the old-old of 85+ groups. c.
Race Race is defined as Malaysian and non-Malaysian people.
d. Weight
BMI is a measure of weight adjusted for height and it is calculated as weight in kilograms divided by the square of height in
meters kgm
2
. Underweight people with BMI of 16-18.5, normal people with BMI of 18.5-25 and overweight people with BMI of 25-35.
e. Social Class and Education Level
The social class of a household is recorded based on the occupation of the women. Based on International Labour of Office
Classification ILO, five groups are defined as follows: professional, intermediate occupation, service worker, industrial worker and
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unemployed. Educational level is also classified as uneducated, primary, secondary and tertiary.
f. Menopause Stage
Early menopause is defined as menopause before age 45 and those whose ovaries were removed before menopause. Premature
ovarian failure premature ovarian insufficiency, primary ovarian insufficiency, premature menopause, hypergonadotropic hypogonadism
are the loss of function of the ovaries before age 40. The average age of menopause is 51 years old, but there is no way to predict when an
individual woman will have menopause or begin having symptoms of menopause. The age at which a woman starts having menstrual periods
is also not related to the age of menopause onset, however most women reach menopause between the ages of 45 and 55,
g. Past Medical History
Past medical history of diseases such as endocrine disease, c
ushing‟s syndrome,
hypogonadism, hyperthyroidism,
hyperparathyroidism, renal failure, chronic liver disease, malabsorption syndromes or gastric surgery, rheumatoid arthritis, nutrition deficiency,
cancer, multiple myeloma and osteogenesis imperfecta have also to be considered.
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h. Drug History
Taking drug such as glucocorticoids, antiplatelets Heparin, Warferin,
antiepileptic Phenytoin,
Phenobarbital and
immunosuppressant have to be mentioned. i.
Smoking and Drinking Smoking habit can be classified as non-smoker, light smoker
with 1-4 cigarette per day, moderate smoker with 5-14 cigarette per day and heavy smoker with 15 cigarette per day. Drinking habit can also
be classified as never, light as 1.2 drinks per day, moderate as 2.2 drinks per day and heavy as 3.5 drinks per day.
3. Dependent Variable