Department of Nephrology, Shanghai Jiaotong University Affiliated First People's Hospital, Shanghai, China.
Nephron Clin Pract. 2012;121(3-4):c102-11. doi: 10.1159/000345159. Epub 2012 Nov 22.
Previous studies have reported that reduced mortality rates in hemodialysis (HD) patients were negatively related to body mass index (BMI). The potentially protective effect of increased BMI in HD patients has been referred to as 'reverse epidemiology'. Our meta-analysis was conducted to examine the relationship between different BMI ranges and mortality in HD patients.
Eligible studies assessing the effects of BMI ranges on all-cause mortality (published from 1966 to February 2012) were searched, using 'hemodialysis' or 'haemodialysis' and 'obese' or 'body mass index' or 'overweight' as key words, in combination with 'mortality', 'survival', 'reverse epidemiology' and 'obesity paradox'. Inclusion criteria were that trials reported mortality in HD patients according to the traditional World Health Organization/National Institutes of Health BMI classification, and BMI levels are acceptable within 2 index points. The quality of the trials was evaluated using the risk of bias assessment in studies included in Cochrane reviews. The mortality rates in HD patients were the primary end point of the study. With no significant heterogeneity, a fixed-effects model was used for analyses.
Four studies with a total of 81,423 patients met final inclusion criteria. Compared to individuals with non-elevated BMI, those with elevated BMI (BMI ≥25, OR 0.67, 95% CI 0.65-0.68) had a lower all-cause mortality. In a risk-adjusted sensitivity analysis, elevated BMI levels (adjusted hazard ratio 0.94, 95% CI 0.92-0.96) remained protective against mortality.
High BMI levels were associated with lower all-cause mortality rates in HD patients. It is possible that more stable hemodynamic status, cytokine and neurohormonal alternations contribute to the protective effects of BMI on mortality in HD patients. There is a need for prospective studies to elucidate mechanisms behind this relationship.
既往研究报道，血液透析（HD）患者的死亡率降低与体重指数（BMI）呈负相关。在 HD 患者中，BMI 增加具有保护作用，这种现象被称为“反向流行病学”。本 meta 分析旨在探讨不同 BMI 范围与 HD 患者死亡率之间的关系。
使用“血液透析”或“血液滤过”和“肥胖”或“体重指数”或“超重”作为关键词，结合“死亡率”、“存活率”、“反向流行病学”和“肥胖悖论”，检索评估 BMI 范围对全因死亡率影响的研究（发表于 1966 年至 2012 年 2 月）。纳入标准为：根据世界卫生组织/美国国立卫生研究院 BMI 分类标准报告 HD 患者死亡率的试验，以及 BMI 水平在 2 个指数点内可接受的试验。使用 Cochrane 综述中纳入研究的偏倚风险评估来评估试验质量。HD 患者的死亡率是该研究的主要终点。如果没有显著的异质性，采用固定效应模型进行分析。
共有 4 项研究，总计 81423 例患者符合最终纳入标准。与非超重 BMI 患者相比，超重 BMI（BMI≥25）患者的全因死亡率较低（OR 0.67，95%CI 0.65-0.68）。在风险调整后的敏感性分析中，升高的 BMI 水平（调整后的危险比 0.94，95%CI 0.92-0.96）仍然对死亡率有保护作用。
高 BMI 水平与 HD 患者的全因死亡率降低相关。更稳定的血液动力学状态、细胞因子和神经激素改变可能是 BMI 对 HD 患者死亡率具有保护作用的原因。需要前瞻性研究来阐明这种关系背后的机制。
