维他命D值低与黄斑部病变风险有关


  【24drs.com】根据在线发表于4月2日Maturitas期刊的一篇系统回顾与一篇统合分析,体内的25-hydroxyvitamin D (25OHD)浓度最低的成年人,发生老年性黄斑部病变(age-related macular degeneration,AMD)的风险最高。
  
  法国Angers大学医院Cedric Annweiler博士等人写道,这篇统合分析的结果,强化了维他命D缺乏和AMD之间有关联的观念,尤其是在该疾病的后期(P=0.002);因此,针对维他命D缺乏进行处置可能可以改善AMD的预后。
  
  研究者使用Medline查找2015年11月前的资料,在发现的243篇研究中,有11篇研究符合他们的筛选准则。准则是,有关于AMD诊断(至少一眼)与维他命D浓度等结果资料的观察型或介入型研究。
  
  这些研究中,7篇是横断面研究、1篇是案例报告、1篇是案例控制研究、1篇是回溯纵向世代研究、1篇是不一致性的兄弟姐妹世代研究,样本数介于65-17,045名研究对象;患有AMD的人数介于31 -1440人。研究者将AMD分类为整体、早期或后期,这些研究都是在2007年后发表。
  
  包含3篇研究的一项统合分析中,共纳入1,126名黄斑部病变患者、8,206名对照组,分析发现黄斑部病变者体内的维他命D值平均比没有黄斑部病变者低15% (95%信赖区间[CI],-41%至11%),不过,这个差异未达显著程度(P = .272)。
  
  另一篇分析中,体内的维他命D值居于最高的五分之一者,发生AMD的机率远低于最少的五分之一者。相较于维他命D值最低者,维他命D值最高者发生AMD的机率减少83%(胜算比[OR]为0.83;95% CI, 0.71 - 0.97),后期AMD的机率降低47%(OR, 0.47;95% CI, 0.28 - 0.79)。
  
  此外,体内的维他命D值低于50 nmol/L的研究对象,发生后期AMD的风险是浓度较高者的2倍以上(OR, 2.18;95% CI, 1.34 - 3.56),不过,当考量所有AMD案例、不论病程阶段时,这项关联并不显著(OR, 1.26;95% CI, 0.90 - 1.76)。
  
  虽然作者主张维他命D值低可能会造成AMD,但是维他命D缺乏可能无法完全解释此情况之发生与恶化,另外,也还不清楚维他命D补充品是否可以预防发生AMD。
  
  他们也承认,目前没有有效的理论可以完全解释体内维他命D值和后期AMD的关联,而较低的维他命D值也可能是因为黄斑部退化导致。
  
  作者们解释,在这种情况下,原发性异常可能是因为AMD造成的视力偏低,其次是功能自主的相关损失、饮食摄取和日晒减少,最终引起维他命D缺乏。由单一篇纵向研究提出的这个假设尽管不是无效的,但是未获以下事实支持,此处所用的大多数[ORs]值,都有校正身体质量指数和/或季节/阳光曝晒时间/休闲体育活动。
  
  资料来源:http://www.24drs.com/
  
  Native link:Low Vitamin D Levels Linked to Macular Degeneration Risk

Low Vitamin D Levels Linked to Macular Degeneration Risk

By Tara Haelle
Medscape Medical News

Adults with the lowest concentrations of circulating 25-hydroxyvitamin D (25OHD) had the highest risk for age-related macular degeneration (AMD), according to a new systematic review and meta-analysis published online April 2 in Maturitas.

"The findings of the present meta-analysis strengthen the idea that there might be a link between vitamin D deficiency and AMD, notably at the late stages of the disease (P=0.002)," write Cedric Annweiler, MD, PhD, from Angers University Hospital in France, and colleagues. "It may therefore be possible that correction of vitamin D deficiency could improve the prognosis of AMD."

The researchers used a Medline search through November 2015 to identify 11 studies that met their selection criteria, out of an initial 243 found. The criteria included observational or interventional studies and outcomes based on data about AMD diagnoses (in at least one eye) and circulating vitamin D concentration.

Among the studies, seven were cross-sectional, one was a case series, one was a case–control study, one was a retrospective longitudinal cohort study, and one was a discordant sibling cohort. They ranged in size from 65 to 17,045 participants; from 31 to 1440 participants had AMD. The researchers categorized AMD as whole, early, or late. All the studies had been published since 2007.

A meta-analysis of three studies, including 1126 participants with macular degeneration and 8206 without, found that those with macular degeneration had circulating vitamin D levels an average 15% (95% confidence interval [CI], ?41% to 11%) lower than those without macular degeneration, but the difference was not significant (P = .272).

In a second analysis, those in the highest quintile of circulating vitamin D levels had the lowest odds of AMD compared with those in the lowest quintile. Those with the highest vitamin D levels had 83% lower odds of AMD (odds ratio [OR], 0.83; 95% CI, 0.71 - 0.97) and 47% lower odds of late AMD (OR, 0.47; 95% CI, 0.28 - 0.79) compared with those with the lowest levels.

In addition, participants with less than 50 nmol/L circulating vitamin D had more than twice the odds of late AMD (OR, 2.18; 95% CI, 1.34 - 3.56) than those with higher concentrations. However, this association dropped out of significance when all AMD cases, regardless of stage, were considered (OR, 1.26; 95% CI, 0.90 - 1.76).

Although the authors argue for the possibility that low vitamin D levels may contribute to AMD, they state that vitamin D deficiency may not fully explain development and worsening of the condition. Further, it is unclear whether vitamin D supplementation would be protective against developing AMD.

They also acknowledge that no validated theory currently exists that can fully explain an association between circulating vitamin D levels and late-stage AMD, and that lower vitamin D levels may result from macular degeneration.

"In this scenario, the primary abnormality would be low vision due to AMD, followed by related loss of functional autonomy, reduction in dietary intakes and sunlight exposure, which can ultimately cause vitamin D deficiency," the authors explain. "This hypothesis, although not invalidated by the single longitudinal study reported here, was yet not supported by the fact that most [ORs] used here were adjusted for body mass index and/or for season/sunlight exposure time/recreational physical activity."

No external funding was used for the study. The authors have disclosed no relevant financial relationships.

Maturitas. Published online April 2, 2016.

    
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