Clinical Briefs By Russell H. Greenfield, MD
With Comments from Russell H. Greenfield, MD, Dr. Greenfield is Clinical Assistant Professor, School of Medicine, University of North Carolina, Chapel Hill, NC; and Visiting Assistant Professor, University of Arizona, College of Medicine, Tucson, AZ.
Understanding the Fine Print: Food Labels
Source: Rothman RL, et al. Patient understanding of food labels: The role of literacy and numeracy. Am J Prev Med 2006;31:391-398.
Goal: To examine the ability of people to read and fully grasp nutrition information found in food labels.
Study design: Cross-sectional trial.
Subjects: A convenience sample of 200 primary care patients (ages 18-80 years) recruited from an academic primary care clinic serving people from a wide socioeconomic range.
Methods: A 24-item measure of food label comprehension (Nutrition Label Survey, or NLS) was administered that required examination of actual food labels collected from a local grocery store. Literacy was measured using the Rapid Estimate of Adult Literacy in Medicine (REALM), and numeracy was evaluated using the Wide Range Achievement Test (WRAT-3). Subjects completed the questionnaires immediately before or after their clinic appointments.
Results: The vast majority of subjects reported using food labels (89%). Three-quarters of participants reported at least high school education, with some college education described by 68%. Slightly more than 75% showed at least 9th-grade reading skills on testing, but only 37% exhibited 9th-grade math skills. About 69% of patients answered food label questions correctly. The most common mistakes involved misapplication of serving size, incorrect calculations, and confusion related to extraneous information included in labeling. Higher levels of income, education, literacy, and numeracy were associated with better comprehension of food labels. Older age, being African American, being obese, and not having private health insurance were associated with lower scores on the NLS. The relationship between performance on the NLS and numeracy was linear, but that between NLS score and literacy was nonlinear.
Conclusion: Patient understanding of current nutrition labeling is often inadequate, potentially impacting clinical outcome for those with chronic illness.
Study strengths: Painstaking methodology; use of everyday food labels.
Study weaknesses: Small sample size; limitations implicit in a cross-sectional study (results imply association, not causation); measurement tools employed (WRAT-3 mainly measures calculation skills though it reportedly correlates with numeracy, and REALM defines the highest level of literacy as 9th grade or above); generalizability (participants were mostly well-educated); no tie-in to any patient's unique chronic illness.
Of note: Approximately 90 million Americans possess literacy and numeracy skills inadequate to function effectively in today's health care environment; the nutrition labeling format was changed in 1993 to help improve consumer use; in this study, only 37% of subjects could correctly calculate the number of carbohydrates present in a 20-ounce soda bottle that contained 2.5 servings, while only 60% were able to calculate the number of carbohydrates in 1/2 bagel when the serving size was a whole bagel; more than 40% of subjects had a chronic illness where dietary intervention would be deemed important, and 23% reported being on a specific diet; a 1996 food survey found that food-label use increased after the revisions of 1993, but a full 70% still wanted labeling that was easier to understand; the order of questions presented to subjects in this trial was altered with every other patient to try to address the impact of fatigue on study results.
We knew that: Comprehension of nutrition labeling can be of critical importance, especially for those with chronic illnesses like diabetes, obesity, and cardiovascular disease; nutrition labeling is mandatory for most packaged food in the United States and is regulated by both the FDA and USDA; standard labeling includes information on serving size, calorie content, percent daily value based on a 2,000 calorie diet, nutrient information, and information on recommended daily values for 2,000- and 2,500-calorie diets; studies have shown that people with poor literacy skills have worse understanding of their chronic illnesses, and often worse clinical outcomes.
Comments: We health care providers often speak to our patients about specific dietary practices, but a significant proportion of people may not be able to understand the labeling found on most supermarket products, and thus may not be eating optimally even when trying to follow our advice. As the results of this trial show, even people with higher levels of education can struggle to interpret food labels. While this article may help spur action on making food labeling less complex, such action will not take place overnight. In the meantime, helping our patients find and understand information on the number of servings contained in a package, and how that translates into calorie and nutrient intake, may make it easier for them to adhere to recommended dietary practices.
What to do with this article: Keep a hard copy in your file cabinet.
Of Bugs and Brains: Pesticides and Parkinson's
Source: Ascherio A, et al. Pesticide exposure and risk for Parkinson's disease. Ann Neurol 2006;60:197-203.
Goal: To determine whether people exposed to pesticides have a higher risk for Parkinson's disease (PD) than the general population.
Study design: Prospective cohort study.
Subjects: A subset of participants in the Cancer Prevention Study (CPS) II Nutrition Cohort (n = 143,325 people who returned the 2001 survey and did not have PD in 1992 [baseline]).
Methods: In 1982, as part of the CPS II mortality study, participants from a cohort of 1.2 million people completed a survey that included questions on occupation and exposure to a variety of chemicals, including pesticides. Subjects were also asked about duration of exposure and occupation. In 1992, a questionnaire on lifestyle and dietary habits was completed that included questions on factors like smoking and exercise. Follow-up surveys occurred in 1997, 1999, and 2001, with the last survey including questions on lifetime occurrence of PD. Follow-up ended in 2001 for subjects without PD, or at the time of diagnosis for those with PD. Those who reported a diagnosis of PD in 2001 were asked for permission to review their medical records and to contact their neurologists for confirmation.
Results: Pesticide exposure was reported by 8% of men and 3% of women. Those who reported pesticide exposure were 14 times more likely to be farmers, ranchers, or fishermen and twice as likely to be blue collar workers than those not exposed. A total of 413 incident cases of PD were included in the analysis. The mean age of onset of PD (70 years) was unrelated to pesticide/herbicide exposure, but lifetime risk for development of PD was 70% higher among those exposed to pesticides/herbicides when analysis was adjusted for age, gender, and smoking. None of the other exposures that were evaluated was associated with an increased risk of PD.
Conclusion: Findings of this large prospective trial support the hypothesis that exposure to pesticides is a risk factor for later development of PD.
Study strengths: Large sample size; prospective nature; degree of follow-up (89% of all living cohort members responded to the 2001 survey); confirmation of PD diagnosis, in part by specialist in movement disorders who was blinded to trial; analyses adjusted for known risk factors for PD.
Study weaknesses: Generalizability (participants were 98% Caucasian); lack of multiple comparisons; lack of information on specific types of pesticides as well as limited data on duration, frequency, and intensity of exposure; data on exposure only collected once and in 1982.
Of note: Questions on exposures focused on many agents including asbestos, coal dust, gasoline exhaust, and chemical solvents; MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropiridine) has a chemical structure similar to the herbicide paraquat and has previously been shown to cause degeneration of dopaminergic neurons and subsequent PD; rotenone and other pesticides have also been shown to have selective dopaminergic toxicity; except for occupation, most dietary and lifestyle measures were not significantly different between those exposed and those not exposed to pesticides; data for men and women were presented together because there was no apparent difference in risk of PD secondary to pesticide exposure by gender; only 28% of subjects provided data on duration of exposure to pesticides (no difference in risk for those exposed for > 10 years as opposed to < 10 years).
We knew that: Results of twin studies suggest that factors apart from genetics play a causative role in PD; several ecological and case-control studies suggest an increased risk of PD with pesticide exposure (however case-control studies can be affected by both recall and selection bias); prior prospective trials of pesticide exposure have suggested an increased risk of PD, but results have not been consistent; postmortem studies report high levels of organochlorine insecticides in the substantia nigra or striatum of people with PD, suggesting that unlike organophosphates and most other pesticides, organochlorine insecticides persist in tissue for years after exposure has ceased; studies suggest an increased risk for PD with rural residence, use of private wells, farming, and exposure to insecticides/herbicides; a meta-analysis of case-control studies showed that risk of PD is approximately 90% higher among people with pesticide exposure as compared to those not so exposed.
Comments: These and other data strongly suggest an association between pesticide exposure and subsequent development of PD, but they do not establish cause and effect. As the researchers readily point out, exposure to pesticides could be a marker for other aspects of rural living that actually cause PD. However, in this study farmers not exposed to pesticides were not at increased risk for PD. The results of this trial do not easily lend themselves to clinical action in the office, but do compel us to recommend caution with respect to lawn care and garden practices as pertains to herbicides and insecticides.
What to do with this article: Make copies to hand out to your peers.
"Feelings—Nothing More Than…"—Emotional Health and Spinal Fusion
Source: Trief PM, et al. Emotional health predicts pain and function after fusion: A prospective multicenter study. Spine 2006;31:823-830.
Goal: To determine what effect, if any, emotional health before lumbar spinal fusion surgery has on postsurgical pain and function in both short- and long-term follow-up.
Study design: Data taken from a large, prospective, multisite trial evaluating two different anterior lumbar fusion systems (investigational device experiment).
Subjects: People aged 26-67 years with lumbar degenerative disc disease who had failed to improve with conservative therapy over a period of at least six months (baseline assessments available for n = 160).
Methods: All subjects underwent fusion at the same sites and by the same physicians, the only difference being the type of lumbar cage used. Participants completed a battery of questions prior to surgery addressing health-related quality of life, back and leg pain, and function (SF-36, visual analog pain scale, and the Oswestry Disability Index). The same questionnaires were completed again at one and two years postsurgery.
Results: Significant improvements in function and back and leg pain were reported by most participants at both 12 and 24 months. Better emotional heath prior to fusion predicted less back and leg pain up to two years following surgery, and improved function at one year post-op. Interestingly, smoking, workers' compensation, and second surgeries were associated with worse postoperative pain and function in most measures.
Conclusion: Presurgical emotional status predicts functionality at one year after surgery and pain a full two years after lumbar fusion surgery.
Study strengths: Prospective nature of trial; multiple measures.
Study weaknesses: Results were included in the analysis for 22 subjects (13.8%) who required a second procedure before follow-up assessment (usually due to medical complications); lack of data on those who refused participation in trial; significant attrition, which could easily impact results (data available for assessment on 160 subjects at surgery, 155 at 12 months, and 115 at 24 months); no data available on presence of comorbidities.
Of note: The National Center for Health Statistics estimated that more than 192,000 spinal fusions were performed in the United States in 1997; most patients, unfortunately, do continue to have some residual pain and less than normal function following spinal fusion; a 1992 systematic review showed that only an average of 68% of those undergoing fusion surgery had satisfactory outcomes, but new techniques have been developed since that time; participants in this trial could have undergone no more than two prior nonfusion surgeries at the same lumbar level; 37.5% of participants were receiving workers' compensation disability payments at the beginning of the study; those who reported higher levels of pain and poorer function also had more pain or poorer function postsurgery.
We knew that: Back pain is the leading cause of disability and lost production in the United States, with cost estimates reaching $170 billion per annum for industrial-related back pain; persistence of pain or limited function following spinal fusion contributes to costs both financial and emotional; scores on subscales of the SF-36 can be aggregated to create both a Physical Component Score (PCS) and a Mental Component Score (MCS), the latter focusing on scores related to social functioning, role limitations caused by emotional problems, mental health, and vitality subscales.
Clinical import: Methodology weakens the findings of this study but the trends are clinically important, as well as commonsensical. Most of us have witnessed patients with wide-ranging attitudes having very different clinical outcomes. Were there effective means available to help optimize a person's mood before surgical intervention we might be able to lessen risk for subsequent complications. The authors of this trial call for additional studies to explore whether specific preoperative interventions might ameliorate postlumbar fusion pain and impaired function, especially in those with poor emotional health; however, numerous trials already exist showing improvements in postoperative outcomes when therapies like guided imagery or clinical hypnosis are employed perioperatively. A small number of trials of cognitive behavioral therapy likewise show promise in this setting. There comes a time when even the most skeptical of us admits that paying attention to a patient's mood can impact their physical outcome after a procedure. Additional sound efficacy studies are warranted, no doubt, but a focus on specific perioperative intervention programs and feasibility would also be welcome.
What to do with this article: Keep a copy of the abstract on your computer.Greenfield RH. Understanding the fine print: Food labels. Altern Med Alert 2007;10(1):9-10. Greenfield RH. Of bugs and brains: Pesticides and Parkinson's. Altern Med Alert 2007;10(1):10-11. Greenfield RH. "Feelings—nothing more than…"—Emotional health and spinal fusion. Altern Med Alert 2007;10(1):11-12.
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