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MNT: Gastrointestinal Disorders (2015

Citation:

Cheng J, Brar PS, Lee AR,Green PHR. Body mass index in celiac disease. Beneficial effect of a gluten-free diet. J Clin Gastroenterol. 2010; 44(4): 267-271.

PubMed ID: 19779362
 
Study Design:
Retrospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To investigate the the effect of a gluten-free diet (GFD) on  body mass index (BMI) of celiac disease patients.
Inclusion Criteria:
  • Patients with biopsy-proven celiac disease
  • Age 18 years or older
  • Available BMI
  • Followed by nutritionist within the last six years (upon diagnosis, at three months and annually thereafter).
Exclusion Criteria:
Those poorly responsive to the diet with recurrent symptoms needing evaluation.
Description of Study Protocol:

Recruitment

Subjects obtained from Celiac Disease Center of Columbia database (1981 to 2007).

Design

Retrospective cohort.

Intervention

Retrospective design: Patients were followed by an RD and were counseled to exclude gluten from diet.  

Statistical Analysis

  • Chi square test for differences or associations between categorical variables
  • Student T-test for differences between groups on continuous variables
  • Generalized regression models for predictors of BMI change.
Data Collection Summary:

Timing of Measurements

Baseline (prior to GFD) and end point (mean 2.8±2.7years overall).

Dependent Variables

BMI change.

Independent Variables

Counseling and follow up by an RD on exclusion of gluten in the diet.

Description of Actual Data Sample:

Initial N

  • Total: 369
  • Female: N=248 (67.2%)
  • Male: N=121 (32.8%)
  • P=0.02.

Attrition (final N)

A total of 0%.

Age

Overall mean: 46.2 (15.5) years.

Other Relevant Demographics

  • Majority presented without anemia: N=187 (50.2%)
  • Majority had Marsh LLB/C or total/sub-total villous atrophy: N=213 (61.2%)
  • Note: Marsh categories define level of villous histology with three as villous atrophy and zero as normal.

Anthropometrics

  • BMI before GFD: 22.4± 4.5 (median 21.4, range 14.8 to 42.8)
  • Normal weight: 60/7%
  • Underweight: 17.3%
  • Overweight: 15.2%
  • Obese: 6.8%.

BMI Categories

 BMI (kg/m2)  Total (N/%) Female (N/%) Male (N/%)
Less than 18.5 64 (17.3) 53 (21.3)* 11 (9.1)*
18.5 to 24.9 224 (60.7) 152 (61.3) 72 (59.5)
25 to 29.9 56 (15.2) 28 (11.3) 28 (23.1)
30 or higher 25 (6.8) 15 (6.1)** 10 (8.3)**

*P=0.02; **P=0.002.

Location

Columbia University, New York.

 

Summary of Results:
Key Findings
  • Greater proportion of females with low BMI than males (21.3% vs. 9.1%)
  • Greater proportion of males were overweight compared to females (23.1% vs. 11.3%) (P=0.002).


 Table 1. Changes in BMI Over Time for BMI Categories

  Less Than 18.5 18.5 to 24.9 25 to 29.9 More Than 30 P-value
Pre-GFD BMI (Mean±SD) 17.3±0.9 21.4±1.7 27.1±1.3 33.8±3.8  
Post-GFD BMI (Mean±SD) 19.0±2.7 21.7±2.3 26.8±2.4 33.3±3.9  
Follow-up length, y (Mean±SD) 3.8±6.6 2.7±2.8 2.1±1.8 1.7±1.1 <0.0001

Other Findings

 Table 2. BMI Comparison Between Study Sample and NHANES III Data:

 
  Study Sample (N=369) NHANES III P-value

Female (mean)
   BMI—Normal
   BMI—overweight

 
21.9
61%
11%
24.2
34%
21%
0.0001
 
0.0001
Males
  
   BMI—Normal (%)
   BMI—Underweight (%)

 
 
59.5%
9.1%
 
34%
26.7%
 
 
0.0001

Overall Findings

  • Significant correlation between change in BMI and duration of follow-up (R=0.68, P<0.0001)
  • BMI change associated with baseline presentation of diarrhea (55.1% with a BMI increase vs. 40.5% with a BMI decrease and 4.4% of those who had no BMI change, P=0.0084)
  • 42.4% initially underweight achieved normal weight
  • 3.4% initially underweight  became overweight
  • 1.7% initially underweight became obese
  • 6.5% initially normal weight became underweight
  • 6.5% initially normal weight became overweight
  • 16.7% initially overweight achieved normal weight
  • 6.3% initially overweight become obese
  • 5.9% initially obese became overweight
  • Villous atrophy improved in each BMI group per histology (P=0.09)
  • Biopsy change and BMI change significantly associated (P=0.05). The greatest histologic improvement was in those with BMI decrease (50.48%).

 

Author Conclusion:
A GFD had beneficial impact on change in BMI and biopsy status. Underweight patients gained weight and overweight or obese patients lost weight. The authors attribute their excellent results to involvement of a dietitian since a critical component in CD management is dietary compliance.
Funding Source:
Other: None reported
Reviewer Comments:
  • Observational study design does not allow for cause and effect
  • Time between pre-measures and post-measures varied significantly for individuals in different BMI categories, which could influence findings
  • Not clear how many patients were also counseled to lose or gain weight
  • Exercise could affect BMI change; there was no mention of this in the study
  • Not clear if weight was measured or self-reported and documented
  • Adherence to GFD was not reported.
Quality Criteria Checklist: Primary Research
Relevance Questions
  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
 
Validity Questions
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? No
2. Was the selection of study subjects/patients free from bias? Yes
  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? No
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  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? No
  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? N/A
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? No
  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? No
  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? No
  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? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  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? No
  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? No
  7.7. Were the measurements conducted consistently across groups? ???
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)? No
  8.6. Was clinical significance as well as statistical significance reported? No
  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