Arshad Anwar, Rashid Rozita, Benjamin Kim
Rheumatic Diseases Unit, Putra Specialist Center, Alor Setar, Kedah, Malaysia.
Mod Rheumatol. 2007;17(6):470-5. doi: 10.1007/s10165-007-0628-1. Epub 2007 Dec 20.
Rheumatoid arthritis (RA) is a chronic joint disease of undetermined cause that is associated with significant disability. Low-grade fever, anemia, and weight loss are recognized extra-articular features associated with increased disease activity. Weight loss and cachexia are well-established features of RA. The mechanism behind weight loss in RA is not known and may be multifactorial. Reduced energy intake and hypermetabolism are the major two factors frequently implicated in the etiology of RA cachexia. One would expect the effect of the above two factors to be highest during increased disease activity and lowest during remission. The purpose of this study was: (a) to establish whether in RA patients changes in body composition mirror changes in disease activity, (b) to investigate the relation between the energy expenditures and weight loss, (c) to examine the dietary energy intake and its role in weight loss in RA patients, and (d) to investigate the relation between the cytokine interleukin (IL)-6 and other variables including resting energy expenditure (REE), body composition, and acute phase reactants. Fourteen patients with RA were age-, sex-, and race-matched with 14 controls from patients with noninflammatory diseases/soft tissue rheumatism. The measurements included the following: disease activity assessment, anthropometric measurements, indirect calorimetry, and measurements of dietary intake. Blood was collected to measure the acute-phase reactants and IL-6 levels. We demonstrated that loss of fat-free mass (FFM) might accelerate during times of increased disease activity and is only partially restored during periods of reduced disease activity. This probably means that the extent of cachexia in RA patients is determined by the frequency and intensity of disease activity (flare) for a given disease duration. Hypermetabolism with increased REE was more evident during increased disease activity. Hypermetabolism in the face of increased energy intake continued to cause loss of the FFM. Interleukin-6 correlates with increased REE and erythrocyte sedimentation rate. There was no direct association between IL-6 level and low FFM. We conclude that loss of FFM is common in RA, cytokine production in RA is associated with altered energy metabolism, and preservation of FFM is important in maintaining good quality of life in patients with RA.
类风湿关节炎（RA）是一种病因不明的慢性关节疾病，会导致严重残疾。低热、贫血和体重减轻是公认的与疾病活动增加相关的关节外表现。体重减轻和恶病质是RA的既定特征。RA患者体重减轻的机制尚不清楚，可能是多因素的。能量摄入减少和高代谢是RA恶病质病因中经常涉及的两个主要因素。人们预期上述两个因素的影响在疾病活动增加时最高，在缓解期最低。本研究的目的是：（a）确定RA患者的身体成分变化是否反映疾病活动的变化，（b）研究能量消耗与体重减轻之间的关系，（c）检查RA患者的膳食能量摄入及其在体重减轻中的作用，以及（d）研究细胞因子白细胞介素（IL）-6与包括静息能量消耗（REE）、身体成分和急性期反应物在内的其他变量之间的关系。14名RA患者在年龄、性别和种族上与14名非炎性疾病/软组织风湿病患者的对照相匹配。测量包括以下内容：疾病活动评估、人体测量、间接测热法和膳食摄入量测量。采集血液以测量急性期反应物和IL-6水平。我们证明，无脂肪体重（FFM）的丢失可能在疾病活动增加时加速，并且仅在疾病活动减少期间部分恢复。这可能意味着，在给定的疾病持续时间内，RA患者恶病质的程度由疾病活动（发作）的频率和强度决定。疾病活动增加时，REE增加导致的高代谢更为明显。面对能量摄入增加时的高代谢继续导致FFM的丢失。白细胞介素-6与REE增加和红细胞沉降率相关。IL-6水平与低FFM之间没有直接关联。我们得出结论，FFM丢失在RA中很常见，RA中的细胞因子产生与能量代谢改变有关，并且保留FFM对维持RA患者的良好生活质量很重要。
