Allergy epidemic

Peanut allergy is common and its incidence is increasing in Australia and around the world. Action in research and public health is required to understand and control this alarming epidemic, say Australian researchers. A retrospective study of over 700 patients with peanut allergy in the Australian Capital Territory showed that most allergies (90%) developed by the age of 72 months, and peanut allergy increased 2.5-fold between 1995 and 2007. Age of onset and severity of allergic reactions have not changed over time, suggesting that the observed increase is not an artefact of early presentation of milder cases. Later age of the first reaction to peanut was associated with an increased severity of reaction, including anaphylaxis, leading the authors to suggest that delayed introduction might actually increase the risk of more serious reactions. They conclude that longer follow-up of data is required to support this hypothesis, but that peanut allergy needs to be considered a public health issue, particularly in the face of the increasing incidence of this potentially life-long problem.

J Allergy Clin Immunol Online; 12 Feb 2009

Guidance on guidelines

The number of clinical practice guidelines published in recent years has been increasing, and such publications are often considered the pinnacle of appropriate care, prompting US researchers to analyse the evolution of recommendations and the levels of evidence on which guidelines are based. Using the joint cardiovascular practice guidelines of the American College of Cardiology and the American Heart Association between 1984 and 2008, the authors found that the number of recommendations increased by 48%, and that a minority of recommendations were based on level of evidence A, with most based on level of evidence C or expert opinion. They conclude that the process of developing guidelines needs to be improved, and that clinicians should be cautious when using recommendations supported by a tenuous evidence base.

JAMA 2009; 301: 831-841

Fat, protein, carbs?

The debate about the relative merits of weight-loss diets based on varying proportions of nutrients continues to rage in the popular media. Despite this interest, there is conflicting evidence in the scientific literature on the benefits of high-carbohydrate, low-fat and high-protein diets and, in particular, on their long-term effects on weight loss. In an attempt to shed light on the issue, US researchers designed a 2-year randomised controlled trial to compare the effects on bodyweight of various energy-reduced combinations of macronutrients. Over 800 overweight adults were randomly assigned to one of four diets. Two diets were low-fat and two high-fat; two were average-protein and two high-protein. Carbohydrates were added to the diets, ranging from 35% to 65% of energy intake, to allow a dose-response test, and group and individual instructional sessions were offered to all participants. At 2 years, the average weight loss was 4 kg and there was no significant difference between any of the groups in terms of weight loss, satiety, and hunger. Attendance at sessions was strongly associated with weight loss. The authors conclude that any calorie-restricted diet taught with persistence, and preferably tailored to individual preferences, can succeed.

N Engl J Med 2009; 360: 859-873

Suicide and depression

Suicidality appears to be distinguishable from depression and can be viewed as a separate construct, though the two are substantially correlated, say Australian researchers. In a community-based study of over 7000 people who completed depression and suicidality scales, researchers found that people can experience suicidal thoughts and behaviours independent of depression. The findings were stable across different ages and sexes. The authors suggest that suicidality should be conceptualised as a separate syndrome from depression, and that this should be reflected in disease classifications such as DSM and ICD.

Aust N Z J Psychiatry 2009; 43: 208-215

Dr Tanya Grassi, MJA

©The Medical Journal of Australia 2009 www.mja.com.au PRINT ISSN: 0025-729X ONLINE ISSN: 1326-5377