輕微飲食異常的死亡率大於厭食與暴食

作者：Pauline Anderson  
出處：WebMD醫學新聞

　　October 23, 2009 — 新研究顯示，雖然「其他未註明之飲食疾患(eating disorders not otherwise specified，EDNOS)」一般被視為相對輕微，這些疾患的死亡率超過神經性厭食症與暴食症。
　　
　　第一作者、明尼拿波里州明尼蘇達大學精神科教授Scott J. Crow醫師表示，這個新發現可能會改變有關EDNOS的思維，這個飲食異常的總稱可能並不適合厭食與暴食的分類。
　　
　　他向Medscape Psychiatry表示，有些機構將EDNOS視為較不嚴重且不若厭食與暴食般需要治療，根據我們的資料，這不太有道理。
　　
　　研究者也發現，自殺是暴食與其他飲食異常的重要死亡原因。
　　
　　這項研究線上發表於10月15日的美國精神病學期刊(American Journal of Psychiatry)。
　　
　　【主要是女性】
　　該研究包括了1979至1997年間，在明尼蘇達大學飲食異常門診進行評估的1,885名病患；每位病患均完成飲食異常問卷，以評估人口統計學變項、飲食異常行為、治療經驗與其他問題。
　　
　　研究者根據病患自我報告的身高體重計算身體質量指數(BMI)，他們將厭食定義為BMI值小於等於17.5 kg/m2 且對體重增加有恐懼，暴食定義為BMI值大於17.5 kg/m2且最近有暴飲暴食、同時使用利尿劑、緩瀉劑或灌腸；嘔吐；禁食；運動。其他病患則被視為有一種EDNOS。
　　
　　研究者評估國家死亡指標資料庫以獲得有關死亡率的資訊，他們將死因分成四類：自殺、與物質濫用有關、創傷、醫療。
　　
　　毫無意外的，研究對象大多數(95.1%)為女性。最常見的診斷為暴食(48.1%)、其次為EDNOS (42.5%)與厭食(9.4%)。
　　
　　【死亡率令人驚訝】
　　EDNOS死亡率為5.2%。相對的，暴食死亡率為3.9% — 高於其他研究的報告數據。Crow醫師表示，這可能是因為其他研究用來確認死亡率的方法較薄弱，且追蹤病患的期間較短。此外，該研究中，有病患實際上有厭食症，但是在死亡時是符合暴食的準則。
　　
　　Crow醫師表示，厭食死亡率為4.0%，低於其他報告的數據。
　　
　　EDNOS病患的死亡率增加，大部份是在一些特定族群，研究者目前正在分析這些資料。
　　
　　Crow醫師表示，其中有些高死亡率是令人驚訝的。就歷史觀點看來，人們一般會說，在暴食或EDNOS看不到死亡率。
　　
　　Crow醫師表示，這個新資訊對於考量改變「精神疾病的診斷及統計手冊第5版」的診斷分類時會有幫助。
　　
　　【暴食之自殺】
　　另一個重要發現是，自殺是暴食與其他兩組的重要死亡原因(暴食有0.9%的死亡是自殺、EDNOS有0.5%、厭食有0.6%)。Crow醫師表示，一般認為暴食症病患的自殺率低於其他飲食異常者。
　　
　　該研究並未包括飲食異常病患死因的詳情，但是Crow醫師表示，這類病患可能有血液電解質異常、心臟病發作、餓死(厭食症患者)、嘔吐與過量使用緩瀉劑(暴食症患者)等併發症風險。
　　
　　本研究的診斷是根據飲食異常問卷中的病患自我報告資料，並沒有特定疾病的發作日期。其他研究限制為，只在單一機構進行，並未包括暴飲暴食的病患，也因為試圖確認死因，研究對象對於自殺率可能少報。
　　
　　【有關暴食的新發現】
　　馬里蘭州巴爾的摩約翰霍普金斯大學醫學院飲食異常計畫助理主任Graham Redgrave醫師接受Medscape Psychiatry邀請對這些發現發表評論時表示，他認為這是個極好的研究，主要是因為研究樣本夠大，包括了許多暴食症病患，且嚴謹的查明死因。
　　
　　他表示，就某方面來說，我對於暴食症的統計最感驚訝，因為以前未曾發表過；就我所知，暴食症的死亡率增加與自殺風險增加都是新發現。Redgrave醫師指出，因為該研究只有包括門診病患，它揭露的飲食異常死亡率可能未能反應實際情況，但是它們的確代表社區的典型病患。
　　
　　暴食比較可能在門診中心進行治療，所以這對於我們告知暴食症病患有關死亡率風險增加特別有幫助。
　　
　　Redgrave醫師同意有些EDNOS案例可能會是嚴重的。他使用一名BMI從35 kg/m2急速降低到20 kg/m2的婦女作為例子。BMI值降低了15，這可能是因為極大的壓力且會增加死亡風險，就算她是所謂的正常體重也是如此。
　　
　　Crow醫師指出他接受GlaxoSmithKline、Ortho-McNeil與Pfizer等藥廠的研究支持，以及Eli Lilly藥廠的發言獎金。研究作者之一、Carol B. Peterson博士接受Guilford Press的版稅。其他作者皆宣告沒有相關財務關係。
　　
　　Am J Psychiatry. 線上發表於2009年10月15日。

Mortality From "Mild" Eating Disorders Greater Than Rates for Anorexia and Bulimia

By Pauline Anderson
Medscape Medical News

October 23, 2009 — Although "eating disorders not otherwise specified" (EDNOS) are often considered relatively mild, the associated mortality rate for these disorders exceeds that for anorexia nervosa and bulimia, new research shows.

This new finding may change the thinking surrounding EDNOS, which have traditionally been a catch-all label for eating disorders that do not fit into the categories of anorexia or bulimia nervosa, said the study's lead author, Scott J. Crow, MD, professor of psychiatry, University of Minnesota, Minneapolis.

"Some facilities view [EDNOS] as less severe and less in need of treatment than bulimia or anorexia, and that just doesn't make much sense according to our data," he told Medscape Psychiatry.

The researchers also found that suicide was an important cause of death for bulimia and other eating disorders.

The study was published online October 15 in the American Journal of Psychiatry.

Subjects Predominantly Women

The study included 1885 patients who were evaluated at the Outpatient Eating Disorders Clinic at the University of Minnesota between 1979 and 1997. Each patient completed an Eating Disorders Questionnaire to assess demographic variables, eating-disordered behaviors, and treatment experiences, among other things.

Researchers calculated body mass index (BMI) from self-reported weight and height. They defined anorexia as a BMI of 17.5 kg/m2 or less and a fear of weight gain, and bulimia as a BMI of more than 17.5 kg/m2 with recent regular binge-eating episodes plus use of diuretics, laxatives, or enemas; vomiting; fasting; or exercise. All other patients were considered to have an EDNOS.

To obtain information on mortality, researchers accessed the National Death Index database. They classified causes of death into 4 categories: suicide, substance-use related, traumatic, and medical.

Not surprisingly, the majority of participants in the study (95.1%) were women. The most common diagnosis was bulimia (48.1%), followed by EDNOS (42.5%) and anorexia (9.4%).

Mortality Rates Surprising

The EDNOS mortality rate was 5.2%. In comparison, the mortality rate for bulimia was 3.9% — higher than rates reported in other studies. This could be because other studies used a weaker method for establishing mortality and followed-up patients for a shorter period of time, said Dr. Crow. As well, the study may have captured patients who actually had anorexia but who had met criteria for bulimia at the time of their death.

The mortality rate for anorexia (4.0%) was lower than that reported in some other studies, said Dr. Crow.

The elevated mortality rate among patients with an EDNOS was largely contained in certain subpopulations, and the researchers are currently analyzing these data.

Some of these high mortality rates were surprising, said Dr. Crow. "Looking at it from the historical perspective, people have tended to say that you just don't see mortality in bulimia or in EDNOS."

This new information may be useful when considering changes to diagnostic categories in the revised Diagnostic and Statistical Manual of Mental Disorders, 5th edition, said Dr. Crow.

Suicide in Bulimia

Another significant finding was that suicide was an important cause of death in bulimia as well as the other 2 groups (0.9% of deaths in bulimia compared with 0.5% in EDNOS and 0.6% in anorexia). The prevailing opinion has been that the suicide rate among patients with bulimia was lower than for other eating disorders, said Dr. Crow.

This study did not include extensive detail on causes of death among patients with eating disorders, but Dr. Crow said such patients may be at risk from complications such as blood electrolyte problems, heart attack, and starvation in the case of anorexia, and vomiting and excessive laxative use in the case of bulimia.

The diagnoses used in this study were based on patient self-report data from the Eating Disorders Questionnaire that do not provide a specific illness-onset date. Other limitations of the study were that it was conducted at only one site, did not include patients with binge-eating disorder, and as with all attempts to determine cause of death, suicide rates may have been underreported.

New Findings on Bulimia

Asked by Medscape Psychiatry to comment on the findings, Graham Redgrave, MD, assistant director, Eating Disorder Program, John Hopkins University School of Medicine, Baltimore, Maryland, said he found the study "fascinating" and significant because of its size, the inclusion of a large number of patients with bulimia, and its rigorous ascertainment of cause of death.

"In some ways I was most surprised about the bulimia statistics because they have never been shown before; as far as I'm aware, both the increased mortality and increased risk of suicide in bulimia are new findings," he said.

Dr. Redgrave pointed out that because the study included only outpatients, the mortality rates for eating disorders that it uncovered might not reflect the true picture. But they do represent typical patients in the community. "Bulimia is much more likely to be treated in an outpatient center, so it's particularly helpful for us to be able to tell our patients with bulimia that there is in fact an increased [mortality] risk."

Dr. Redgrave agreed that some cases of EDNOS can be serious. He used the example of a woman who quickly drops from a BMI of 35 kg/m2 to a BMI of 20 kg/m2. "That's a loss of 15 BMI points, which may be incredibly stressful and increase risk for death, even though that woman may be at normal weight."

Dr. Crow reports he has received research support from GlaxoSmithKline, Ortho-McNeil, and Pfizer and speakers honoraria from Eli Lilly. Study investigator Carol B. Peterson, PhD, receives royalties from Guilford Press. All other authors have disclosed no relevant financial relationships.

Am J Psychiatry. Published online October 15, 2009.