People withrheumatoid arthritis(RA) who are obese are less likely to achieve disease remission than their non-obese counterparts, according to a meta-analysis published in May inArthritis Care and Research.The review also found that obesity was associated with higher levels of disease activity and pain, suggesting excess weight may negatively affect overall outcomes in RA. This meta-analysis supports earlier research, including astudypresented at the 2015 annual meeting of the American College of Rheumatology.
有强有力的证据表明，肥胖会增加患类风湿性关节炎的风险，但人们对其对患者的影响知之甚少。因此，研究人员回顾了3500多项关于肥胖与四个关键指标之间关系的研究:缓解率、疾病活动度、患者报告的随访结果和死亡率。
他们确定了20项符合纳入标准的研究;其中8个只关注缓解率。这些研究在规模(有些研究的肥胖患者数量相对较少)、设计和及时性(所有研究都是在过去五年内发表的，但有些研究的数据要追溯到几十年前)方面各不相同。尽管如此，结果还是相似的。
在调整了可能影响结果的因素后，如年龄、性别和症状持续时间，肥胖患者达到缓解的可能性比正常体重或超重的患者低43%，达到持续缓解的可能性低51%。Obesity was defined as a body mass index (BMI) greater than 30 and overweight as a BMI of 25 to 29.9 – classifications used by the World Health Organization.
尽管个别研究的作者对缓解的定义略有不同，但它通常意味着很少或没有临床疾病的迹象——包括很少有压痛或肿胀的关节;炎症的低血标志物，如c反应蛋白(CRP)或红细胞沉降率(ESR或“sed率”);改善了疼痛和功能。为了荟萃分析的目的，持续缓解指的是在一项特定研究中连续几个时间点出现的缓解，例如，在6个月、9个月和1年。
More disease activity, pain
When the researchers looked at other measures, including disease activity, patient-reported outcomes and mortality, they again found that many studies, though not all, reached similar conclusions. In general, obesity was associated with worse disease activity and pain as well as higher counts of tender (but not swollen) joints and inflammation markers.
The researchers did not see higher mortality rates in obese patients – in fact, just the opposite. But that finding may be skewed, according to co-author Gilaad G. Kaplan, MD, an associate professor in the departments of medicine and community health sciences at the University of Calgary, in Alberta, Canada. Dr. Kaplan explains that the studies he and his colleagues reviewed showed inconsistent results; ultimately there wasn’t enough data to know definitively whether obesity has a negative effect on mortality. It also wasn’t possible to determine if a particular treatment plan or medication affected outcomes (some RA medications are known to be less effective in overweight and obese patients) because different studies used different drug regimens and/or switched patients between medications during the study period.
Why obesity produces such poor outcomes isn’t clear, although the researchers point out that fat releases proteins (cytokines) that drive inflammation throughout the body; many of these cytokines are identical to those produced by inflamed joint tissue. They also note that obesity may make some arthritis drugs less effective. People who are obese may also have other health issues that restrict which medications can be used.
Whatever the reason, it’s clear that people with RA who are obese fare worse than those who are not. In one sense, this is good news because weight is something people can try to change. However, more studies are needed to determine if weight loss will, indeed, improve outcomes for obese patients with RA, Dr. Kaplan says.
Vivian Bykerk, MD, a rheumatologist at Hospital for Special Surgery (HSS) in New York City, thinks obese andoverweight patients need to start losing weight now. Dr. Bykerk was not involved in the meta-analysis, but she and her colleagues at HSS recently studied obesity in 1,000 newly diagnosed RA patients. They found that only 28 percent of those who were obese achieved sustained remission compared to 48 percent of normal-weight patients, despite receiving similar, guideline-based treatments.
The key message from both investigations, she says, is that “modifiable lifestyle factors such as smoking and obesity must be addressed in order for people with rheumatoid arthritis to achieve their treatment targets. Obesity rates in RA are approaching [those] of the general population and are having a significant negative impact in patients with rheumatoid arthritis.” (According to just-released statistics from the Centers for Disease Control and Prevention, 40 percent of U.S. women and 35 percent of men are obese).
Dr. Bykerk says it’s essential to put in place strategies to help people with RA lose weight, but that “those who have lived with long-standing RA and accumulated joint damage that has reduced mobility may find it even more difficult to achieve a healthier weight.”
Author: Linda Rath for the Arthritis Foundation
Related Resources:
- Being Overweight Can Hurt Rheumatoid Arthritis Remission
- Learn More About Rheumatoid Arthritis
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