MNT: Weight Management (2015)
Hoy MK, Winters BL, Chlebowski RT, Papoutsakis C, Shapiro A, Lubin MP, Thomson CA, Grosvenor MB, Copeland T, Falk E, Day K, Blackburn GL. Implementing a low-fat eating plan in the Women's Intervention Nutrition Study. J Am Diet Assoc. 2009; 109: 688-696.PubMed ID: 19328264
To evaluate if a lifestyle intervention targeting reducing fat intake influences breast cancer recurrence rates in women with early-stage, resected disease receiving conventional cancer management.
- Participants had histologically confirmed, resected invasive breast cancer
- Between 48 years and 79 years old
- Were within 365 days of cancer surgery
- Dietary intake of fat at baseline had to be less than 20% of total caloric intake
- Acceptable adjuvant cancer therapy was required and included radiation, select chemotherapies (required for hormone receptor negative cancers) and tamoxifen for receptor positive cancers.
If subjects did not meet the inclusion criteria.
Recruitment for the Women's Intervention Nutrition Study (WINS) was described elsewhere, but subjects were recruited from multiple center sites.
Randomized controlled clinical trial. Subjects were randomized into either the Low Fat Eating Plan (LFEP) Intervention group, which aimed for 15% of calories as fat (between 20g to 30g daily) and provided intensive long-term counseling to help participants maintain the LFEP, or the control group that received healthy eating information, but no specific nutrition intervention.
Subjects were not blinded to which group they were in; however, interviewers obtaining diet recalls were blinded to which group subjects were in when collecting the 24-hour food records.
- The intervention was delivered by trained registered dietitians who applied behavioral, cognitive and motivational counseling techniques
- The LFEP initiated with an initial intensive intervention phase lasting for months one to four, with eight bi-weekly individual counseling sessions, followed by a maintenance phase (months five up to and including year five). During the maintenance phase, participants visited with RDs every three months and also had optional monthly group sessions. Self-monitoring, goal setting and motivational interviewing strategies were key components.
Differences in baseline variables between and within groups were analyzed using T-test or paired T-tests. The T-tests were performed to compare differences in the nutrient intakes and anthropometric variables and corresponding 95% CIs were reported.
Timing of Measurements
- A 24-hour food recall was obtained at baseline, three months and annually via phone
- At study entry, subjects were given a daily fat gram goal calculated based on body weight, with the cutoff range of 20g to 30g of fat
- Individual sessions with the dietitian focusing on counseling and behavioral modification occurred bimonthly for the first four months, then quarterly for months five through year five, with optional monthly group meetings.
- Breast cancer recurrence rates.
- Dietary fat was calculated for all subjects based on weight: Weight (in pounds)/six equal fat grams per day with the aim of between 20g to 30g daily. Those less than 120 lbs did not consume less than 20g of fat, and those higher than 180 lbs did not consume more than 30g of fat daily
- Periodic unannounced 24-hour food recalls were obtained to ensure subjects remained compliant with the LFEP
- Counseling for those in the LFEP intervention group was based on the social cognitive theory of behavior change and included goal setting, self monitoring, modeling and social support. Relapse prevention and management techniques were used to maintain adherence. The goal was to educate on the LFEP and guide participants to long-term maintenance of this diet.
- Each visit with the dietitian followed a specific outline or plan such that all RDs were working with subjects equally:
|Intensive Intervention Visit Number||Topics Covered|
|2||Counting fat grams, setting goals|
|5||Individualize to promote adherence, menu planning|
|6||Individualize, recipe modification|
|7||Individualize, selecting fast and easy meals|
|8||Individualize, eating out|
|9||Individualize, quick guide for recipes and food labels|
|10||Individualize, positive and negative self-talk|
|11||Individualize, coping with appetite and food cues|
|12||Individualize, packing your lunch|
|14||WINS breakfast, lunch and dinner suggestions|
|15||Healthy eating on WINS|
|16||Individual modules focused on planning for long-term adherence|
A total of 2,437 women were randomly assigned, with 975 to the intervention group (LFEP) and 1,462 to the control group.
Attrition (Final N)
- In the control group, 66 were lost to follow-up and 106 discontinued study participation
- In the intervention group, 45 were lost to follow up and 170 discontinued
- Only six reported that there lack of continuing was due to a dislike of the low-fat diet.
At baseline, body weight was closely comparable in the randomization groups (160.2±35.1 lbs, and 160.0±35.0 lbs in the intervention and control groups, respectively).
Multiple sites across the United States; exact locations were not discussed.
- Information on dietary intake was available for 975 and 1,461 of women in the dietary intervention group and the control group, respectively, at baseline; for 840 and 1,328 women respectively, at year one; for 654 and 1,077 women, respectively, at year three; and for 380 and 648 women, respectively, at year five
- Dietary fat intake were closely comparable at baseline between both groups
- After one year, dietary fat was reduced to a greater extent in the intervention group as compared to the control group and this reduction was maintained throughout the study
- At five years, the dietary fat gram intake was 53.9±26.7g in the control group and 34.9±18.4g in the intervention group (P<0.0001)
- This represented 31.4±23.2% and 23.2±8.4% of energy intake as fat in the control and intervention groups, respectively
- Dietary fat intake was consistently lower in the intervention compared with the control group at all time points (percent energy from fat at 60 months 23.2±8.4% vs. 31.2±8.9%, respectively,
P<0.0001) and was associated with mean 6.1 lb mean weight difference between groups (P=0.005) at five years (baseline and five years, respectively: control 160.0±35.0 lb and 161.7±32.8 lb; intervention 160.2±35.1 and 155.6±32.1 lb).
- The WINS LFEP resulted in significant and sustained reductions in both fat intake as well as body weight
- These results lend support to fact that modification of dietary interventions can be successfully implemented over an extended period of time
- Breast cancer recurrence was less frequent in women randomized to the intervention group (previously reported).
The WINS LFEP is a comprehensive, theory-based lifestyle intervention that did result in reduced fat intake and modest weight loss over time. In addition, the LFEP suggested a favorable effect on breast cancer recurrence rates, especially in post-menopausal women with hormone receptor negative disease. The WINS counseling program may provide a strategy for implementation of this LFEP in clinical practice.
|Government:||National Cancer Institute, National Institutes of Health, Department of Health and Human Services|
Similarity of groups not discussed; groups not similarly sized.
Quality Criteria Checklist: Primary Research
|1.||Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)||Yes|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||Yes|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||Yes|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||Yes|
|1.||Was the research question clearly stated?||Yes|
|1.1.||Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?||Yes|
|1.2.||Was (were) the outcome(s) [dependent variable(s)] clearly indicated?||Yes|
|1.3.||Were the target population and setting specified?||Yes|
|2.||Was the selection of study subjects/patients free from bias?||???|
|2.1.||Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?||Yes|
|2.2.||Were criteria applied equally to all study groups?||Yes|
|2.3.||Were health, demographics, and other characteristics of subjects described?||No|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||???|
|3.||Were study groups comparable?||???|
|3.1.||Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)||???|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||???|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||Yes|
|3.4.||If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?||N/A|
|3.5.||If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)||N/A|
|3.6.||If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?||N/A|
|4.||Was method of handling withdrawals described?||Yes|
|4.1.||Were follow-up methods described and the same for all groups?||Yes|
|4.2.||Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)||Yes|
|4.3.||Were all enrolled subjects/patients (in the original sample) accounted for?||Yes|
|4.4.||Were reasons for withdrawals similar across groups?||Yes|
|4.5.||If diagnostic test, was decision to perform reference test not dependent on results of test under study?||N/A|
|5.||Was blinding used to prevent introduction of bias?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||Yes|
|5.2.||Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)||Yes|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||N/A|
|5.4.||In case control study, was case definition explicit and case ascertainment not influenced by exposure status?||N/A|
|5.5.||In diagnostic study, were test results blinded to patient history and other test results?||N/A|
|6.||Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?||Yes|
|6.1.||In RCT or other intervention trial, were protocols described for all regimens studied?||Yes|
|6.2.||In observational study, were interventions, study settings, and clinicians/provider described?||N/A|
|6.3.||Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?||Yes|
|6.4.||Was the amount of exposure and, if relevant, subject/patient compliance measured?||Yes|
|6.5.||Were co-interventions (e.g., ancillary treatments, other therapies) described?||N/A|
|6.6.||Were extra or unplanned treatments described?||N/A|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||Yes|
|6.8.||In diagnostic study, were details of test administration and replication sufficient?||N/A|
|7.||Were outcomes clearly defined and the measurements valid and reliable?||Yes|
|7.1.||Were primary and secondary endpoints described and relevant to the question?||Yes|
|7.2.||Were nutrition measures appropriate to question and outcomes of concern?||Yes|
|7.3.||Was the period of follow-up long enough for important outcome(s) to occur?||Yes|
|7.4.||Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?||Yes|
|7.5.||Was the measurement of effect at an appropriate level of precision?||Yes|
|7.6.||Were other factors accounted for (measured) that could affect outcomes?||???|
|7.7.||Were the measurements conducted consistently across groups?||Yes|
|8.||Was the statistical analysis appropriate for the study design and type of outcome indicators?||Yes|
|8.1.||Were statistical analyses adequately described and the results reported appropriately?||Yes|
|8.2.||Were correct statistical tests used and assumptions of test not violated?||Yes|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||Yes|
|8.4.||Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||???|
|8.6.||Was clinical significance as well as statistical significance reported?||Yes|
|8.7.||If negative findings, was a power calculation reported to address type 2 error?||N/A|
|9.||Are conclusions supported by results with biases and limitations taken into consideration?||Yes|
|9.1.||Is there a discussion of findings?||Yes|
|9.2.||Are biases and study limitations identified and discussed?||Yes|
|10.||Is bias due to study's funding or sponsorship unlikely?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|