Clinical question: Are dietary intervention with low-fat, Mediterranean or low-carbohydrate diets effective?
Background: Obesity is a growing, worldwide problem. Past trials comparing the effectiveness and safety of various dietary interventions have been limited by short follow up and high dropout rates.
Study design: Prospective randomized trial.
Setting: Employees of a research center in Israel.
Synopsis: 322 subjects (average BMI 31) were randomized to a low-fat/restricted-calorie, Mediterranean/ restricted-calorie, or a low-carbohydrate/non-restricted calorie diet. Diet adherence was 84.6% at two years and all groups lost significant amounts of weight. The Mediterranean and low-carbohydrate diets showed similar aver∆age weight loss of 4.4 kg and 4.7 kg, respectively. The low-fat diet group on average lost 2.9 kg. Diabetic patients had improved glycemic control and lower insulin levels with the Mediterranean diet. Subjects assigned to the low-carbohydrate diet had the greatest improvement in lipid profile (20% relative decrease of total cholesterol to HDL ratio).
The trial took place at a single site (a scientific research center in Israel) and included only 14% women, so its generalization is uncertain. The study was based on self-reported dietary intake and may be subject to reporting bias.
Bottom line: Mediterranean and low-carbohydrate diets are safe and effective alternatives to low-fat diets with favorable effects on glycemic control in diabetics and lipid metabolism, respectively.
Citation: Shai I, Schwarz-fuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. NEJM. 2008;359(3):229-241.
Admissions for Acute Coronary Syndrome Decreased after Implementation of Smoke-free Legislation
Clinical question: Is there a reduction in admissions for acute coronary syndrome (ACS) after enactment of smoke-free legislation?
Background: Multiple, small, retrospective studies have shown a decrease in ACS after implementation of smoke-free legislation.
Study design: Prospective observational multi-center cohort study.
Setting: Nine hospitals in Scotland.
Synopsis: Data was collected on all patients admitted with ACS 10 months before and after implementation of smoke-free legislation, which prohibited smoking in all enclosed public and work places in Scotland. After the smoking ban, the number of ACS admissions fell by 17% (95% CI 16-18) in Scotland as a whole, compared with a 4% reduction in England during the same period (England does not have similar smoke-free legislation). Among smokers, former smokers and non-smokers, the number of ACS admissions decreased by 14% (95% CI 12-16), 19% (95% CI 17-21), and 21% (95% CI 18-24), respectively. Among non-smokers, self-reported exposure to second-hand smoke decreased significantly; these reductions were confirmed by measured reductions in serum cotinine levels, even among those who never smoked.
Results were limited by the observational nature of the study, although the authors did attempt to carefully match comparison cohorts by season and geography. Also, secular trends other than legislation may have reduced prevalent smoking in Scotland during the study period.
Bottom line: Admissions for ACS for both smokers and non-smokers decreased after implementation of smoke-free legislation.
Citation: Pell JP, Haw S, Cobbe S, et al. Smoke-free legislation and hospitalizations for acute coronary syndrome. NEJM. 2008;359(5):482-491.
Continuation of Beta-blockers in Patients Hospitalized for Heart Failure Improves Mortality
Clinical question: Does the withdrawal or continuation of beta-blockers in patients hospitalized with decompensated heart failure have any effect on clinical outcomes?
Background: Previous clinical trials have demonstrated mortality benefit with the use of beta-blockers in patients with symptomatic chronic heart failure and left ventricular systolic dysfunction (LVSD), however, controversy exists whether to continue these medications in acute decompensated heart failure.
Study design: Prospective cohort analysis from the OPTIMIZE-HF registry (Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure).