NC: Diabetes Management (2007)
- To study the short- and long-term effectiveness of a comprehensive weight-reduction program vs. a conventional program in overweight patients with type 2 diabetes
- To identify predictors for the degree of weight loss.
- BMI over 27kg per m2
- Type 2 diabetes, based on WHO criteria.
- History of angina
- History of heart failure
- History of intermittent claudicaiton
- History of proliferative retinopathy
- History of treatent with subcutaneous insulin injections, diuretics, beta-blocking agents, drugs for hyperlipidemia or other drugs influencing carbohydrate metabolism.
Patients recruited from general practices and from an outpatient diabetes clinic.
- Run-in period of three months preceded a two-year treatment period
- Post three-month run-in period, subjects were stratified according to sex to either a 24-month comprehensive weight-reduction program or to a 24-month conventional weight-reduction program.
Three-month run-in period to ensure weight stabilization:
- During "run-in" period, all subjects were seen at least three times
- Measurements were obtained during the run-in period following a 12-hour overnight fast
- Subjects seen by dietitian twice
- Prior to each visit, subjects completed a three-day food record
- During the visit, the dietitian checked food intake records for accuracy and obtained additional information as necessary
- Subjects were instructed not to change dietary habits during the run-in period.
Following the run-in period, subjects were stratified to one of two 24-month treatment groups:
- Conventional Program
- Subjects visit outpatient clinic at 2 month intervals and seen by physician and dietitian every visit
- At each visit the following occurs:
- The various measurement results obtained during run-in period are recorded in booklet form and provided as feedback during each visit
- Dietitian provides dietary education
- Adherence to diet recommendations assessed on each visit via 3-day food record (completed by subject prior to each visit)
- Comprehensive Program
Consists of all components of the conventional program plus:
- Sessions on behavior modification strategies
- Conducted in group format (eight to 10 subjects)
- Led by a psychologist experienced in eating disorders
- Sessions held once per week during the first two months and thereafter at Months Four, Eight, 12, 16 and 20
- Behavioral strategies taught include self-monitoring, stimulus control techniques, self-reinforcement, cognitive restructuring appraoches and relapse prevention methods.
- Exercise training
- Group format (five or six subjects), led by two physiotherapists
- Three periods of three-month duration
- Frequency of training sessions
- Twice per week during Months Three through Six
- Once per week during Months Nine through 12 and Months 15 through 18.
- Session content
- Five minutes warm-up
- Training on bicycle ergometer for 30 minutes (intensity 60% to 80% of maximal heart rate)
- 30 minutes of various sports activities
- Five-minute cool-down.
- Subjects were encouraged to exercise every day at home and increase regular daily activity.
- Sessions on behavior modification strategies
- Run-in clinical and metabolic data on both groups was compared using Wilcoxon's rank-sum test
- To compare effects of both programs on various variates, median changes for each were compared at the six-, 12- and 24-month time points, using Wilcoxon's rank sum test
- Overall effect of both programs computed by assessing the average difference of the changes for each program over the two-year treatment period using Hodges-Lehmann estimator. Additionally, a 95% confidence interval was computed to compare the effects of each program.
- Spearman correlation coefficients used to describe associations between changes in body weight and other variates
- Because correlation coefficients were similar for the separate therapy groups, only results of combined analyses were provided
- Multiple linear regression techniques were used to investigate whether the magnitude of weight loss at 24 months could be predicted by subject and metabolic characteristics measured at baseline
- To avoid confound by treatment, all tested models included a variate-indicating therapy
- Variates were built step-by-step into prediction model in forward fashion using the following rules: Significance at 10% level, the maximal increment in variance explained (R2)
- Special attention was given to underlying assumptions of Gaussian-distributed residuals.
Timing of Measurements
- During the three-month run-in period: "At least" three times (specific times not indicated)
- During the two-year treatment period: Every two months (e.g., Months Two, Four, Six and so on up to Month 24).
Run-in period (post 12-hour overnight fast)
- Body weight (without shoes and heavy clothing on calibrated balance scale to nearest 0.1kg)
- Body composition (via bioelectrial impedance analysis with tetrapolar device)
- Blood pressure measured in supine position (in triplicate with London School of Hygiene mercury sphygmomanometer)
- Waist-to-hip ratio (WHR) calculated by dividing waist circumference measure (at level of minimal girth) by hip circumference measure (at level of maximal circumference over buttocks)
- Venous blood samples drawn with minimal venous occlusion.
Run-in period, visits with dietitian (measures obtained before each visit)
- Three-day food record (two weekdays and one weekend day)
- Food record information converted to energy and macronutrient intake (using Dutch Food Composition Table 1986 and nutrient software package "voeding" (current version: Stichting NEFO, TNO-voeding, Zeist, the Netherlands).
Two-year treatment period
- Every two months (e.g., Months Two, Four, Six and so on up to Month 24): Three-day food record (two weekdays and one weekend day) converted to energy and macronutrient intake (as described in run-in period).
Primary aim clinical variables
- Body weight (without shoes and heavy clothing on calibrated balance scale to nearest 0.1kg)
- Body fat percentage (via bioelectrial impedance analysis with tetrapolar device)
- WHR (calculated by dividing waist circumference measure, at level of minimal girth, by hip circumference measure, at level of maximal circumference over buttocks
- Systolic blood pressure (mmHg)
- Diastolic blood pressure (mmHg)
- Blood pressure was measured in the supine position (in triplicate with London School of Hygiene mercury sphygmomanometer).
Primary aim metabolic variables (obtained in fasting state)
- HbA1c (percentage): Inter-assay coefficient of variation (CV) of 3.3%, determined by ion-exchange high-performance liquid chromotography (modular diabetes monitoring system, Bio-Rad Lab BV, Veenendaal, Netherlands)
- Plasma insulin (intra-assay CV 7%): Measured by RIA (insik4, Sorin Biomedia, Saluggia, Italy)
- C-peptide (intra-assay CV 4%): By RIA (Diagnostic Systems Lab, Texas, USA)
- Triglycerides (intra- and inter-assay CV 0.5 and 3.5%): Measured enzymatically by GPO-PAP method (Boehringer Mannheim GmbH, Mannheim, Germany)
- Serum cholesterol (intra- and inter-assay CV 0.8 and 1.1%): Measured enzymatically by CHOD-PAP method (Boehringer Mannheim GmbH, Mannheim, Germany)
- HDL2: Performed by density gradient ultracentrifugation, using modification of procedure described by Terpstra et al (inter-assay CV 8.6%).
- Behavior modification
- Exercise training.
- Moderate energy-restricted diet designed to reduce usual energy intake by 500kcal, with minimum intake of 1,000kcal every 24 hours
- Diet prescription composed of:
- 50% to 55% carbohydrate
- 15% protein
- 30% fat calories (emphasizing use of unsaturated fat).
- Cholesterol: Under 300mg per day
- Fiber: Approximately 25g.
|Variables||Comprehensive Program||Conventional Program|
- Differences (95% CI) between change in body weight in CPP, compared to CVP after six and 24 months of treatment were -2.2kg (-4.0kg, -0.3kg), P=0.03 and -1.3kg (-3.3kg, 0.7kg), P=0.21, respectively
- CPP resulted in greater decrease (95% CI) of HbA1c after six months: -0.8% (-1.2%, -0.2%), P=0.01, but not after two years: -0.4% (-1.0%, 0.1%), P=0.12
- The only serum lipid that decreased significantly was serum total cholesterol in the CPP, compared to CVP at six and 12 months: -0.4mmol (-0.7mmol, -0.1mmol) per L (P=0.04) and -0.4mmol (-0.8mmol, -0.1mmol) per L (P=0.03), respectively.
- In the short-term (six months), the comprehensive program produced significantly lower HgA1C levels, but this difference did not persist to 12 months
- The long-term outcome of the conventional program was not significantly different from that of the comprehensive program.
- Included patients who were already treated for "quite a while" at the outpatient diabetic clinic
- Authors do not state whether subjects were randomly assigned to groups
- Actual timing of measurements during the run-in period were not specified
- Due to outliers, median values were used to compare characteristics of subjects during the run-in period, however no P-values were provided to indicate significance
- The run-in period was used to ensure "weight stabilization before outset of study," however no statistics were run to indicate that this occurred.
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?||???|
|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?||Yes|
|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?||Yes|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||N/A|
|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?||N/A|
|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?||???|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||No|
|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?||N/A|
|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?||???|
|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?||???|
|7.5.||Was the measurement of effect at an appropriate level of precision?||???|
|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?||N/A|
|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)?||Yes|
|8.6.||Was clinical significance as well as statistical significance reported?||???|
|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|