Is a low-fat or a low-carbohydrate diet more effective in causing weight loss and improving cardiovascular disease risk?
More than 40 years ago Dr. Robert Atkins wrote his first book advocating for a low-carbohydrate diet to cause and sustain weight loss. "Told ya!" he might say if he were still here. This study (of mostly women) found that a low-carb diet -- though not as severe a diet as the Atkins approach -- caused an average 3.5 kg greater weight loss than a low-fat diet. Both diet approaches were undertaken without any caloric restriction; in other words, these were low-carbohydrate and low-fat, not low-calorie, diets. (LOE = 1b-)
Bazzano LA, Hu T, Reynolds K, et al. Effects of low-carbohydrate and low-fat diets: A randomized trial. Ann Intern Med 2014;161(5):309-318.
Study design: Randomized controlled trial (nonblinded)
Funding source: Government
Setting: Outpatient (any)
The 148 participants were volunteers from the general public: 88% were women and 50% were black. They were randomized, concealed allocation uncertain, to a diet of fewer than 40 g carbohydrates per day (the Atkins diet suggests fewer than 20 g/day) or a diet aimed to keep fat to less than 30% of daily energy intake, which is in line with the diet recommended by the National Cholesterol Education Program in the United States. Neither diet included a specific calorie goal. Participants in both groups received significant counseling consisting of individual weekly sessions with a dietitian for the first 4 weeks followed by small-group counseling sessions every other week for the next 5 months. At 12 months, the low-carb diet group lost an average 3.5 kg more than the low-fat diet group (?5.3 kg vs ?1.8 kg). They also had greater reductions in fat mass and higher lean mass gains. Though total cholesterol levels did not markedly change in either group, high-density lipoprotein levels increased significantly more in the low-carb group and triglyceride levels decreased significantly more in that group, as well. Blood pressure, glucose levels, and insulin levels were not different between the groups.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Is the combination of varenicline and nicotine replacement therapy more effective than varenicline alone in achieving long-term smoking cessation in adults?
The combination of varenicline (Chantix) and nicotine replacement therapy is more effective than varenicline alone in achieving smoking abstinence at 12 weeks and 24 weeks in adult smokers. (LOE = 1b)
Koegelenberg CF, Noor F, Bateman ED, et al. Efficacy of varenicline combined with nicotine replacement therapy vs varenicline alone for smoking cessation. A randomized clinical trial JAMA 2014;312(2):155-161.
Study design: Randomized controlled trial (double-blinded)
Funding source: Industry
Optimal combinations of therapy for achieving smoking cessation in adults remain uncertain. These investigators identified relatively healthy smokers, aged 18 years to 75 years, seeking assistance for smoking cessation. Eligible participants (N = 446) with a history of smoking at least 10 cigarettes per day during the previous year randomly received (concealed allocation assignment) varenicline (0.5 mg once daily for 3 days, titrated to 0.5 mg twice daily for days 4 to 7, and then to the maintenance dose of 1 mg twice daily for a total of 12 weeks) and either active 15-mg nicotine patches (applied topically for 16 hours each day, beginning 2 weeks before the target quit date and continuing for a total of 14 weeks) or matched placebo patches. Outcomes included self-reported use of nicotine-containing products with verification by measurement of exhaled carbon monoxide levels. Both patients and clinicians remained masked to treatment group assignment. Complete follow-up occurred for 88% of participants at 24 weeks. Individuals discontinuing the study or lost to follow-up were considered smokers in the per-protocol and intention-to-treat calculations of abstinence rates. Using a per-protocol analysis (including only patients who took at least one or more doses of varenicline while using the randomized patch), patients receiving varenicline and active nicotine replacement therapy were significantly more likely to achieve smoking abstinence at 24 weeks than those using varenicline and the placebo patch (65.1% vs 46.7%; number needed to treat [NNT] = 6; 95% CI, 4 - 11). Using intention-to-treat analysis, continuous abstinence at 12 weeks occurred in 44.6% of patients receiving active nicotine replacement therapy compared with 31.3% of those receiving placebo (NNT= 7.5; 4.5 - 23.0). There was no significant group difference in mean weight gain.
David Slawson, MD
Director of Information Sciences
University of Virginia Health System
Does smoking cessation affect mental health?
Improvement in anxiety, depression, and mixed anxiety/depression was associated with quitting smoking in this follow-up analysis of studies of smoking cessation. Similarly, improved measures of stress, positive affect, and psychological quality of life are also associated with quitting. The changes in anxiety and depression incidence are similar to those seen following pharmacologic treatment of these disorders. It's possible that people who had improved mood were more likely to quit, though it's unlikely given that the changes occurred following cessation. (LOE = 2a-)
Taylor G, McNeill A, Girling A, Farley A, Lindson-Hawley N, Aveyard P. Change in mental health after smoking cessation: systematic review and meta-analysis. BMJ 2014;348:g1151.
Study design: Meta-analysis (other)
Funding source: Foundation
Setting: Various (meta-analysis)
These researchers searched 5 databases, including Cochrane Central and reference lists of included studies, and assembled 26 observational studies in any language that evaluated mental health before smoking cessation and at least 6 weeks after cessation, comparing patients who successfully quit with those who continued to smoke. Fourteen of the studies drew patients from the general population and 4 studies enrolled patients with psychiatric disorders. Two investigators identified eligible studies and extracted the data. Most of the studies were judged to be high quality. Anxiety, evaluated in 4 studies at a median of 6 months following cessation, was slightly better in nonsmokers (standardized mean difference [SMD] = -.37; 95% CI, -.03 to -.70), though there was significant heterogeneity among the studies. Mixed anxiety and depression was similarly better in nonsmokers (SMD = -.31; -.14 to -.47) without heterogeneity. In 10 studies that evaluated depression, nonsmoking was associated with a significant decrease in depression from baseline to 1 year after quitting (SMD = -.25; -.12 to -.37). Similarly, measures of stress, positive affect, and psychological quality of life were improved after quitting as compared with baseline. There was no evidence of publication bias. Results were similar whether patients were drawn from a general population or from a cohort with physical or psychiatric disorders.
POEMs are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com(www.essentialevidenceplus.com).
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Top 20 POEMs of 2014