Definition of Variables Independent Variables

48

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, commit to user 49 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 commit to user 50 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. commit to user 51 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