# Prevalence and Predictors of Osteoporosis Among the Chinese Population in Klang Valley, Malaysia
## 2 Materials and Methods  
This cross-sectional study adopted the quota sampling technique to recruit community-living Malaysian Chinese subjects aged \(\geq\)40 years living in Klang Valley, Malaysia. Solicitation of subjects was performed from April-December 2018. Invitations with specific inclusion and exclusion criteria were sent to community centers in Klang Valley and advertised in local newspapers and radio stations. Only subjects fulfilling the inclusion criteria in Table 1 were recruited. The total number of subjects recruited in the study was 408, of which 51 were excluded from the study due to the following reasons: thiazide diuretics users (n = 15), glucocorticoids users (n = 24), receiving cancer treatment (n = 2), having mobility problems (n = 4), and did not complete the study procedures (n = 6). Finally, data for 367 subjects were used in the present study. Informed consent was obtained from all the subjects before their enrolment. The study was approved by the Research Ethics Committee of Universiti Kebangsaan Malaysia (approval code: UKM PPI/111/8/JEP-2017-761). All subjects completed a questionnaire, which included demographic details (ethnicity, occupation, education level, parity, current menstrual status, age of menarche and menopause), medical history, intake of dairy products (milk, yoghurt, and cheese), coffee, tea, and alcohol, and lifestyle practices (smoking habits and physical activity). The subjects were classified based on household income into the bottom 40% (B40, with household income <RM 7640 or USD 1868), the middle 40% (M40, with household income RM 7640-RM 15,159 or USD 1868-USD 3707), and top 20% (T20, with household income \(\geq\)RM 15,160 or USD 3707) groups according to data of the Malaysian census [12]. For the intake of dairy products and beverages, the frequency of consumption was determined. For beverages, an intake of less than one unit per week was defined as non-drinker. One unit of milk was defined as 200 mL, while one unit of coffee/tea was defined as one standard cup [13]. Those who consumed beverages or dairy products 3-4 days per week were defined as regular drinkers. A unit of alcoholic drink referred to a bottle of beer/cider, a glass of wine, or a portion of spirits/strong alcohol according to the National Health Service, U.K. [14]. Due to the low number of subjects who stopped drinking alcohol, both former drinkers and regular drinkers (3-4 days per week) were grouped as \"ever drinker\". Meanwhile, those who consumed rarely (one or fewer days per month) or never consumed at all were grouped as \"non-drinker\". In this study, current smokers and those who abstained from smoking within the past 12 months were grouped as \"ever smoker\". As for calcium supplementation, subjects who consumed at least one tablet of calcium supplement for 3-4 days per week and took it for more than a month were considered as regular consumers. Physical activity status of subjects was assessed using the International Physical Activity Questionnaire (IPAQ), which is freely available online [15]. The total energy expenditure was determined by the multiplication of the duration (in minutes) and the frequency (days) of walking by a factor of 3.3, moderate intensity by a factor of 4, and vigorous intensity by a factor of 8. These were converted to the metabolic equivalent of task (MET) and summed up. Subjects were categorized into inactive, minimally active, or HEPA (health-enhancing physical activity) active based on total MET score or other additional criteria [11; 13]. Subjects' standing height without shoes was measured to the nearest 1 cm using a stadiometer (SECA, Hamburg, Germany). Body weight of subjects with light clothing, but without shoes was measured to the nearest 0.1 kg using a weighing scale (TANITA, Tokyo, Japan). Body mass index (BMI: kg/m\({}^{2}\)) was calculated by dividing body weight (kg) by the square of body height (m\({}^{2}\)).