Primecuts: This Week In the Journals

April 26, 2010

Bora Toklu, MD

Faculty Peer Reviewed

As the spring is phasing in, it’s again that time of the year when an uncomfortable guilt sets in as you recover from the sedentary life of winter and confront those extra pounds that the winter has snuck in. People seem to rely mostly on “diet and exercise” to make it into skimpy summer swim suits—a virtual seasonal ritual of our modern society. There is not much of a dispute over how to exercise, but the toughest part seems to be the rules of healthy nutrition. There are many things in our diet that we can modify for the better and as many that we really can’t.  In fact, there are still others whose potential harms we are not totally aware.  The New York Times seems to be on the topic this month. Several news items (1, 2, 3) made it to New York Times especially covering the hot debates over a possible “soda tax”.  Studies have indicated that the main dietary culprit for both the increase in sugar and the weight of Americans has been the ever-growing consumption of sugary drinks, especially soda.

 (4) In the midst of tax for soda debates came the report that was released by the Institute of Medicine (IOM) last Tuesday, officially stating that Americans consume unhealthy amounts of sodium in their food, far exceeding public health recommendations. Consuming too much sodium increases the risk for high blood pressure and can lead to a variety of diseases. IOM analysts estimate that population-wide reductions in sodium could prevent more than 100,000 deaths annually. Salt is currently considered a safe food ingredient, and there is no limit to how much of it companies can put in their products. Federal dietary guidelines say people should consume no more than 2,300 milligrams of sodium a day, which is equivalent to about a teaspoon of salt. The Centers for Disease Control and Prevention have recommended that people at risk of high blood pressure consume no more than 1,500 milligrams of sodium daily. But the Institute of Medicine report said Americans on average take in about 3,400 milligrams of sodium. The report added that efforts at sodium reduction should seek to lower the average intake to the guideline level of 2,300 milligrams. In this report, the IOM concludes that reducing sodium content in food requires new government standards for the accept­able level of sodium. Manufacturers and restaurants need to meet these standards so that all sources in the food supply are involved. The goal is to slowly, over time, reduce the sodium content of the food supply in a way that goes unnoticed by most consumers as individuals’ taste sensors adjust to the lower levels of sodium.

 (5)Shortly after the IOM report on the sodium intake, the Annals of Internal Medicine published an analysis looking at the cost-effectiveness of 2 population strategies to reduce sodium intake: government collaboration with food manufacturers to voluntarily cut sodium in processed foods, modeled on the United Kingdom experience, vs. a sodium tax. Authors of this analysis created and used a computer-simulated, state-transition (Markov cohort) model of incidence, prevalence, mortality, and direct costs associated with stroke and MI in U.S. adults aged 40 to 85 years. Outcome measures included incremental costs (2008 U.S. dollars), quality-adjusted life-years (QALYs), and MIs and strokes averted.  Results of the analysis estimated that a collaboration with industry that decreases mean population sodium intake by 9.5% averts 513,885 strokes and 480,358 MIs over the lifetime of adults aged 40 to 85 years who are alive today compared with the status quo.  This would increase QALYs by 2.1 million and would save $32.1 billion in medical costs. A tax on sodium that decreases population sodium intake by 6% increases QALYs by 1.3 million and saves $22.4 billion over the same period. Short to say this cost-effectiveness analysis suggests that either population strategy would lead to dramatic decreases in the number of strokes and myocardial infarctions and would save the health system billions of dollars. These findings are consistent with the IOM report and give an upper hand to those in favor of FDA control over the sodium content in food. In the following days we’ll watch and see how FDA will respond to the solidifying data over the concerns for sodium intake in our diet.  It’s quite possible that we are soon to witness another debate over a “salt tax”.

 (6)On the preventive medicine arena, Annals of Internal Medicine published a feasibility study for the ongoing National Lung Screening Trial. National Lung Screening Trial is aiming to define the effectiveness of screening for lung cancer. This randomized, controlled trial of a population of 3190 current or former smokers, aged 55 to 74 years, with a smoking history of 30 pack-years or more and no history of lung cancer randomly assigned patients to low-dose CT versus chest radiography and looked at the false-positive rates. Authors defined false-positive screenings as a positive screening with a completed negative work-up or 12 months or more of follow-up with no lung cancer diagnosis.  By using a Kaplan–Meier analysis, a person’s cumulative probability of 1 or more false-positive low-dose CT examinations was 21% after 1 screening and 33% after 2. The rates for chest radiography were 9% and 15%, respectively. A total of 7% of participants with a false-positive low-dose CT examination and 4% with a false-positive chest radiography had a resulting invasive procedure. These substantial findings warrant further study of resulting economic, psychosocial, and physical burdens of these screening methods and we, as physicians, should keep in mind the high false-positive rates of such imaging modalities when used for lung cancer screening in an asymptomatic population.

 (7)Annals of Internal Medicine took my attention once again this week as they published a study on a quite debatable area: The validity of U.S. News & World Report‘s annual rankings of the top 50 American hospitals. The rankings have been criticized for emphasizing the subjective reputation of hospitals too strongly and this study taking basis from this critique looked at the role of reputation in determining the relative standings of the top 50 hospitals. The rankings are based on a combination of subjective and objective components of quality which are combined as a weighted sum and then transformed into a 100-point scale to create the total U.S. News score. Authors looked at the association between reputation (subjective) score and the total score from all objective measures among the 50 top-ranked hospitals in each specialty. They concluded that on average, rankings based on reputation score alone agreed with U.S. News & World Report‘s overall rankings 100% of the time for the top hospital in each specialty, 97% for the top 5 hospitals, 91% for the top 10 hospitals, and 89% for the top 20 hospitals. The association was strong between the total U.S. News score and reputation score, variable between the total U.S. News score and total objective measures score, and minimal between the reputation score and total objective measures score. This study at its best implies a substantial discrepancy between reputational and objective rankings and I wonder how the rankings would shape around if only objective measures of quality were to be use. This study is just another friendly reminder to all of us not to choose a hospital for its reputation only.

 (8)Diet was again in the journals via EPICOR published in the Archives of Internal Medicine.  A diet with high levels of carbohydrates increases plasma triglyceride levels and reduces high-density lipoprotein (HDL) cholesterol levels, in addition to increasing blood glucose and insulin levels, thereby creating a profile expected to increase the risk of cardiovascular disease (CVD). Moreover, postprandial glycemia is now emerging as an independent risk factor for CVD in diabetic and nondiabetic individuals. Dietary glycemic load (*GL) and glycemic index (*GI) in relation to cardiovascular disease investigated by the EPICOR study made it to the Archives of Internal Medicine this week. EPICOR is a prospective investigation into the causes of CVD and is being performed on Italian cohorts recruited from 1993 to 1998 as part of the European Prospective Investigation into Cancer and Nutrition (EPIC). Study included 44 132 subjects (13 637 men [age range, 35-64 years] and 30495 women [age range, 35-74 years]) who completed a dietary questionnaire at baseline. During a median of 7.9 years of follow-up, 463 CHD cases (158 women and 305 men) were identified. Women in the highest carbohydrate intake quartile had a significantly greater risk of CHD than did those in the lowest quartile (RR, 2.00; 95% CI, 1.16-3.43), with no association found in men (P = .04 for interaction). Increasing carbohydrate intake from high-GI foods was also significantly associated with greater risk of CHD in women (RR, 1.68; 95% CI, 1.02-2.75), whereas increasing the intake of low-GI carbohydrates was not. Women in the highest GL quartile had a significantly greater risk of CHD than did those in the lowest quartile (RR, 2.24; 95% CI, 1.26-3.98), with no significant association in men (P = .03 for interaction). Authors concluded that a high dietary GL and the intake of carbohydrates from high-GI foods increase the overall risk of CHD in women but not men. They also proposed that the adverse effects of a high glycemic diet in women are mediated by sex-related differences in lipoprotein and glucose metabolism. Further prospective studies are required to verify a lack of association of a high dietary GL with CVD in men.

 (9)Dietary carbohydrates have been associated with dyslipidemia. Added sugars (caloric sweeteners used as ingredients in processed or prepared foods) are an increasing and potentially modifiable component in the US diet and their association to dyslipidemia is an uncharted territory. JAMA addressed this in a Cross-sectional study among US adults (n = 6113) from the National Health and Nutrition Examination Survey (NHANES) 1999-2006. Respondents were grouped by intake of added sugars using limits specified in dietary recommendations (< 5% [reference group], 5%-<10%, 10%-<17.5%, 17.5%-<25%, and 25% of total calories). Main outcome measures included adjusted mean high-density lipoprotein cholesterol (HDL-C), geometric mean triglycerides, and mean low-density lipoprotein cholesterol (LDL-C) levels and adjusted odds ratios of dyslipidemia, including low HDL-C levels (<40 mg/dL for men; <50 mg/dL for women), high triglyceride levels ( 150 mg/dL), high LDL-C levels ( 130 mg/dL), or high ratio of triglycerides to HDL-C (>3.8). In this study, authors concluded on a statistically significant correlation between dietary added sugars and blood lipid levels among US adults. Among participants consuming less than 5%, 5% to less than 17.5%, 17.5% to less than 25%, and 25% or greater of total energy as added sugars, adjusted mean HDL-C levels were, respectively, 58.7, 57.5, 53.7, 51.0, and 47.7 mg/dL (P < .001 for linear trend), geometric mean triglyceride levels were 105, 102, 111, 113, and 114 mg/dL (P < .001 for linear trend), and LDL-C levels modified by sex were 116, 115, 118, 121, and 123 mg/dL among women (P = .047 for linear trend). There were no significant trends in LDL-C levels among men. Among higher consumers ( 10% added sugars) the odds of low HDL-C levels were 50% to more than 300% greater compared with the reference group (<5% added sugars). Now I’m curious more to see the association between the added sugar related dyslipidemia and cardiovascular disease and if there is any sex-related differences.

 When it comes to a healthy diet it should be wise to keep in mind not just the size of your swimsuit, but also the quality adjusted life years you will gain in exchange of this simple life style modification.

 * The glycemic index (GI), introduced by Jenkins et al in 1981, is a measure of how much a standard quantity of food raises blood glucose levels compared with a standard quantity of glucose or white bread. The GI is thus an indicator of how quickly a carbohydrate can be absorbed as glucose. Because the amount of carbohydrate in a food (or overall diet) can vary and have a variable influence on the postprandial glycemic response, the glycemic load (GL) measure is also used. The GL is the product of the GI of a food item and the available carbohydrate content of that item.

Dr. Toklu is a first year resident at NYU Langone Medical Center

Peer Reviewed by Judith Brenner, Associate Editor, Clinical Correlations

 References: 

1.  Hartocollis A. Health officials willing to go to the mat over obesity and sugared sodas. New York Times (New York edition). 2010 April 5. Page A15.  http://www.nytimes.com/2010/04/05/health/policy/05daines.html

2.  Brody JE. A tax to combat America’s sugary diet. New York Times (New York edition). 2010 April 6. Page D7.   http://www.nytimes.com/2010/04/06/health/06brod.html

3.  Bittman M. Soda: A sin we sip instead of smoke? New York Times (New York edition). 2010 February 14. Page WK1.  http://www.nytimes.com/2010/02/14/weekinreview/14bittman.html

4.  Henny JE, Anderson CAM, Angell SY, Appel LJ, Beauchamp GK, Briefel RR, Cohen MN, Mireles Dewitt CA, Drescher G, Muth MK, Rubin RJ, Ruff J, Sorensen G, Yetley EA, Taylor CL, Boon CS, Delvalle HB, Ann Miller E, Datiles MJ, Lee S, Bandy A, Kennedo G, Meyers LD. Strategies to reduce sodium intake in the United States. Institute of Medicine of The National Academies – Food and Nutrition Board. 2010 April 20. 4p.  http://www.iom.edu/Reports/2010/Strategies-to-Reduce-Sodium-Intake-in-the-United-States.aspx

 5.   Smith-Spangler CM, Juusola JL, Enns EA, Owens DK, Garber AM. Population strategies to decrease sodium intake and the burden of cardiovascular disease. Annals of Internal Medicine. 2010 April 20;152(8):481-487.   http://www.annals.org/content/152/8/481.abstract

6.   Crosswell JM, Baker SG, Marcus PM, Clapp JD, Kramer BS. Cumulative incidence of false-positive test results in lung cancer screening. Annals of Internal Medicine. 2010 April 20;152(8):505-512.  ) http://www.annals.org/content/152/8/505.abstract

7.   Sehgal AR. The role of reputation in US news and world report’s rankings of the top 50 American hospitals. Annals of Internal Medicine. 2010 April 20;152(8):521-525.  http://www.annals.org/content/152/8/521.abstract

8.   Sieri S, Krogh V, Berrino F, Evangelista A, Agnoli C, Brighenti F, Pellegrini N, Palli D, Masala G, Sacerdote C, Veglia F, Tumino R, Frasca G, Grioni S, Pala V, Mattiello A, Chiodini P, Panico S. Dietary glycemic load and index and risk of coronary heart disease in a large Italian cohort. Arch Intern Med. 2010 April 12;170(7):640-647.  http://archinte.ama-assn.org/cgi/content/abstract/170/7/640

9.   Welsh JA, Sharma A, Abramson JL, Vaccarino V, Gillespie C, Vos MB. Caloric sweetened consumption and dyslipidemia among US adults. JAMA. 2010 April 21;303(15):1490-1497.   http://jama.ama-assn.org/cgi/content/abstract/303/15/1490

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