# Prevalence and Predictors of Osteoporosis Among the Chinese Population in Klang Valley, Malaysia
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{**Variables**} & \multicolumn{1}{c}{**Odds Ratio (OR)**} & \multicolumn{2}{c}{**95\% CI for OR**} & \multicolumn{1}{c}{**\(p\)-Value**} \\  & & **Lower** & **Upper** & **\(p\)-Value** \\ \hline \multicolumn{1}{c}{} & Overall (among both sexes) & & & \\ Age & 1.110 & 1.060 & 1.162 & **<0.001** \\ Body weight & 0.885 & 0.840 & 0.933 & **<0.001** \\ Low monthly income & 11.292 & 2.349 & 54.282 & **0.002** \\ \hline \multicolumn{1}{c}{} & Sub-analysis among men & & & \\ Lean mass & 0.9997 & 0.9995 & 0.9998 & **<0.001** \\ \hline Lean mass & 0.9997 & 0.9995 & 0.9999 & **0.002** \\ Calcium supplement intake & 4.163 & 1.274 & 13.606 & **0.018** \\ Body mass index (BMI): & & & & \\ Underweight vs. normal & 3.543 & 1.029 & 12.198 & **0.045** \\ Overweight vs. normal & 0.517 & 0.087 & 3.066 & 0.467 \\ \multicolumn{1}{c}{} & Education: & & & \\ Secondary school vs. no formal education/primary school & 0.112 & 0.021 & 0.589 & **0.010** \\ Certificate/diploma vs. no formal education/primary school & 0.062 & 0.009 & 0.453 & **0.006** \\ University degree and above vs. no formal education/primary school & 0.037 & 0.003 & 0.437 & **0.009** \\ \hline \multicolumn{1}{c}{} & & & & \\ \end{tabular} The odds ratio was obtained through a multivariate logistic regression model. The predictors are adjusted to each other.  
\end{table} 
Table 4: Predictors of bone health status of the study population. The bolded p-values are statistically significant. number of previous studies [30; 31; 32]. Underweight subjects were shown to have a higher incidence of osteoporosis than those with a BMI \(\geq\) 18.5 kg/m\({}^{2}\) among Mainland Chinese (n = 4988, aged 41-95 years). Lower BMI was found to be positively correlated with osteoporosis [30]. A cross-sectional study in Thailand (n = 4528, age \(\geq\)40 years) also reported that osteoporosis was most commonly found in underweight women (52.1%), followed by those with normal weight (20.3%), those overweight (15.7%), and those obese (9.4%) [31]. Greater BMI or body weight is positively associated with BMD as it imposes mechanical stress on bone, and in response, the bone mass increases to accommodate the load [33; 34]. Adipose tissue also possesses aromatase enzyme, which converts androgen to estrogen, which is protective of bone [35; 36]. BMI may also reflect the nutritional status of the subjects, whereby underweight subjects may be deficient in the vital nutrients to maintain bone health. The positive association between BMI and bone health has been discussed in various geographical regions and populations [37; 38; 39; 40]. However, BMI is a poor determinant of obesity, because it is the excess fat mass that actually defines obesity rather than total body weight (or BMI) [33]. Lean mass, which is a component contributing to body weight aside from fat mass, was observed to predict negatively osteoporosis among the subjects of this study. The muscle can also exert mechanical forces on the bone and maintain its mass. It may also reflect the weight-bearing activity of the subjects, in which muscle mass and bone health are higher in those who are more active. Intake of calcium supplement was a positive predictor of osteoporosis among women in this study. We hypothesized that this observation was caused by the fact that women susceptible to osteoporosis had initiated calcium supplementation prior to joining the study. Calcium supplements have been widely used as a pharmacological agent to prevent bone loss [41; 42; 43]. However, the calcium supplementation might not be persistent or sufficient among women in this study to produce an effect on their bone health. Thus, the relationship was not causal. The majority of the subjects in the present study belonged to the low socio-economic group (95.6%). A lower monthly household income was found to predict osteoporosis among the subjects, especially women, in this study.