Sta Romana M, Li-Yu J T
Department of Epidemiology and Biostatistics, UP College of Public Health, Manila, Philippines.
J Clin Densitom. 2007 Oct-Dec;10(4):386-90. doi: 10.1016/j.jocd.2007.08.001.
This study aims to determine the prevalence of Type 2 diabetes in women with osteoporosis and estimate the odds ratio (OR) of osteoporosis in women with Type 2 diabetes using Bayesian inference. This is a case-control study design that looked into prevalence of diabetes among 582 female patients who had normal bone mineral density (BMD) and 598 female patients with osteoporosis. The subjects included women at least 30 yr of age who had their BMD measured in the lumbar spine and femoral neck using dual-energy X-ray absorptiometry at a tertiary referral center in Manila, Philippines. Prevalence of Type 2 diabetes in subjects with osteoporosis is 22.41%, whereas 19.07% of the subjects with normal BMD had diabetes. The odds of developing osteoporosis is 22.54% higher for Type 2 diabetic subjects. Patients with osteoporosis were older than subjects with normal BMD by almost 10 yr. Of the diabetic osteoporotic patients, 44.78% were physically active compared with 20.72% diabetics with normal BMD. Most of the diabetics (60.36%) with normal BMD were obese, whereas majority of diabetic osteoporotics (64.93%) have normal body mass index (BMI). Less than 10% of both diabetic osteoporotics and diabetics with normal BMD have ever undergone hormone replacement therapy. Of the 598 subjects with osteoporosis, 124 (20.74%) had suffered from fragility fractures. When controlling for physical activity and BMI, the odds of developing osteoporosis was 21.73% and 53.89% higher for Type 2 diabetics, respectively. In considering all possible confounders and effect modifiers (age, physical activity, BMI, and hormone replacement therapy) in the model which made use of a diffuse normal prior distribution, the estimate for OR (Model 1) is 0.67. A separate analysis excluding modifiable confounders (Model 2) gave the measure of association an equal likelihood of diabetes being a protective factor or a risk factor. The crude OR indicated that Type 2 diabetes is a risk factor for osteoporosis. However, when identified confounders were included in the model, the direction of the relationship changed. Considering the credible intervals (95% credible interval in both models), the study concluded that diabetes is indeed a protective factor for osteoporosis. Results of the study may have potential limitations. There are sources of bias that have been identified--selection bias where patients included in the study were referred by primary care givers for a specified reason as well as misclassification and recall biases on certain information such as type and duration of physical activity. Diabetes is a protective factor for osteoporosis in this referred population of women. However, with the well-known diabetes-related factors, that is, microvascular complications, visual acuity, and risk for fall, one should still strongly consider assessing and screening for osteoporosis and fracture risk reduction in diabetic patients.
本研究旨在确定骨质疏松症女性中2型糖尿病的患病率，并使用贝叶斯推断估计2型糖尿病女性中患骨质疏松症的比值比（OR）。这是一项病例对照研究设计，调查了582名骨矿物质密度（BMD）正常的女性患者和598名骨质疏松症女性患者中的糖尿病患病率。研究对象包括至少30岁的女性，她们在菲律宾马尼拉的一家三级转诊中心使用双能X线吸收法测量了腰椎和股骨颈的BMD。骨质疏松症患者中2型糖尿病的患病率为22.41%，而BMD正常的患者中这一比例为19.07%。2型糖尿病患者发生骨质疏松症的几率高出22.54%。骨质疏松症患者比BMD正常的患者年龄大近10岁。在糖尿病骨质疏松症患者中，44.78%身体活跃，而BMD正常的糖尿病患者中这一比例为20.72%。BMD正常的糖尿病患者中大多数（60.36%）肥胖，而大多数糖尿病骨质疏松症患者（64.93%）体重指数（BMI）正常。糖尿病骨质疏松症患者和BMD正常的糖尿病患者中均不到10%曾接受过激素替代疗法。在598名骨质疏松症患者中，124名（20.74%）曾发生脆性骨折。在控制身体活动和BMI后，2型糖尿病患者发生骨质疏松症的几率分别高出21.73%和53.89%。在使用扩散正态先验分布的模型中考虑所有可能的混杂因素和效应修饰因素（年龄、身体活动、BMI和激素替代疗法）后，OR估计值（模型1）为0.67。排除可改变混杂因素的单独分析（模型2）得出的关联度量表明，糖尿病同样有可能是保护因素或风险因素。粗略OR表明2型糖尿病是骨质疏松症的一个风险因素。然而，当将已识别的混杂因素纳入模型时，关系的方向发生了变化。考虑到可信区间（两个模型中的95%可信区间），研究得出结论，糖尿病确实是骨质疏松症的保护因素。本研究结果可能存在潜在局限性。已识别出一些偏差来源——选择偏差，即纳入研究的患者是由初级保健提供者因特定原因转诊而来的，以及在某些信息（如身体活动类型和持续时间）方面的错误分类和回忆偏差。在这一转诊的女性人群中，糖尿病是骨质疏松症的保护因素。然而，鉴于众所周知的与糖尿病相关的因素，即微血管并发症、视力和跌倒风险，仍应强烈考虑对糖尿病患者进行骨质疏松症评估和筛查以及降低骨折风险。
