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MNT: Gastrointestinal Disorders (2015

Citation:
Kabbani TA, Goldberg A, Kelly CP, Pallav K, Tariq S, Peer A, Hansen J, Dennis M, Leffler DA. Body mass index and the risk of obesity in coeliac disease treated with the gluten-free diet. Aliment Pharmacol Ther. 2012; 35 (6): 723-729. PubMed ID: 22316503
 
Study Design:
Retrospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • To analyze changes in BMI in individuals after diagnosis of Celiac Disease (CD) with particular attention to the potential effects of Gluten Free Diet (GFD) adherence on weight change
  • To compare the BMI distributions at diagnosis and after treatment to regional population data from the 2007 National Health Interview Survey (NHIS).
Inclusion Criteria:
  • CD confirmed by biopsy
  • Electronic records in the Celiac Center at Beth Israel Deaconess Medical Center
  • Age 18 and older
  • Gluten-free diet adherence score by a specialized CD dietitian
  • Available BMI measurements on at least two separate hospital visits.
Exclusion Criteria:
  • Under age 18
  • No confirmation of CD by biopsy
  • Only one BMI measurement available
  • No assessment of adherence with a GFD.
Description of Study Protocol:

Recruitment

Review of medical records of patients with known or suspected CD from The Celiac Center at Beth Israel Deaconess Medical Center.

Design

Retrospective study.

Statistical Analysis

  • Performed using SPSS for Windows, Rel. 13.0, 2004
  • Change in BMI over time was analyzed using repeated-measures analysis with Greenhouse-Giesser correction, where appropriate
  • Study outcomes were assessed using Fisher's Exact test or Chi-square test with Yates correction for discrete variables and Student's T-test, as appropriate.
Data Collection Summary:

Timing of Measurements

The mean time between first and last BMI was 39.5 months (range, one to 345 months).

Dependent Variables

  • Changes in BMI (body weight in kg divided by height in m2) weight class from initial to follow-up visits:
    • Underweight: Less than 18.5
    • Normal: 18.5 to 24.9
    • Overweight: 25.0 to 29.9
    • Obese: 30 or higher.
  • GFD adherence was stratified into two groups:
    • Scores 1 or 2: Adequate GFD adherence
    • Scores 3 to 5: Inadequate GFD adherence.

Independent Variables

GFD adherence was determined based on recorded assessment by an expert Celiac dietitian (or from gastroenterologists' notes and serology results), using a five-point rating system.

  • Score of 1 to 2: Excellent or good adherence
  • Score of 3 to 4: Poor adherence
  • Score of 5: Non-adherence.

Control Variables

Percentage of patients with significant weight change: A change of two or more BMI points carried out a priori.

Description of Actual Data Sample:

Initial N

1,018 patients with biopsy-proven celiac disease.

Attrition (Final N)

  • 679 (66.7%) had documentation of BMI and GFD adherence from at least two separate visits
  • 123 (12.1%) patients had only one recorded BMI
  • 216 (21.2%) either had no records of BMI or had no assessment of their adherence with a GFD and were not included.

Age

  All Excluded Subjects
N=339 (% or SD)
Overall Cohort
N=679 (% or SD)
P-value Between Overall Cohort and Excluded Subjects
Age 51.9 (15.5) 52.4 (16) 0.64

Ethnicity

 
All Excluded Subjects
N=339 (% or SD)
Overall Cohort
N=679 (% or SD)
P-value Between Overall Cohort and Excluded Subjects
White (%) 320 (94) 645 (95) 0.66

Other relevant demographics

  All Excluded Subjects
N=339 (% or SD)
Overall Cohort
N=679 (% or SD)
P-value Between Overall Cohort and Excluded Subjects
Demographics Male (%) 92 (27) 166 (24) 0.36
Female (%) 247 (73) 513 (76)  
Initial BMI 24.4 (4.9) 24.0 (5.1) 0.42
Follow-up BMI N/A 24.6 (5.1) N/A
Presentation Gastrointestinal symptoms 209 (62) 424 (62) 0.8
Extra-intestinal symptoms 130 (38) 255 (38)  
BMI Less than 18 (%) 5 (4.1)* 46 (6.8) 0.3
18.5 to 24.9 (%) 72 (58.5)* 416 (61.3) 0.6
25 to 29.9 (%) 28 (22.8)* 139 (20.5) 0.5
30 or more (%) 18 (14.6)* 78 (11.5) 0.4

Anthropometrics

  • Baseline characteristics for included patients and those excluded were similar
  • There were more females than males (76% female)
  • There were more with gastrointestinal symptoms (diarrhea, bloating, abdominal pain, weight loss, nausea, vomiting, GERD, constipation) in 62% vs. non-gastrointestinal signs and symptoms in 38%.

Location

Beth Israel Deaconess Medical Center, Boston, MA.

Summary of Results:
Key Findings

 

 
All Excluded Subjects, N=339 (% or SD) Overall Cohort, N=679 (% or SD) P-value Between Overall Cohort and Excluded Subjects Good Adherence, N=501 (% or SD) Poor Adherence, N=178 (% or SD) P-value Between Good and Poor Adherence Groups
Demographics
    Male (%) 92 (27) 166 (24) 0.36 117 (23) 49 (28) 0.27
    Female (%) 247 (73) 513 (76)   384 (77) 129 (72)  
    Age 51.9 (15.5) 52.4 (16) 0.64 52.2 (16.2) 53 (15.4) 0.57
    White (%) 320 (94) 645 (95) 0.66 473 (94) 172 (97) 0.3
    Initial BMI 24.4 (4.9) 24.0 (5.1) 0.42 23.6 (4.7) 25.4 (6.0) Less than 0.001
    Follow-up BMI N/A 24.6 (5.1) N/A 24.3 (4.7) 25.7 (5.8) 0.001
Presentation
 Gastrointestinal symptoms 209 (62) 424 (62) 0.8 316 (63) 108 (61) 0.67
  Extra-intestinal symptoms 130 (38) 255 (38)   185 (37) 70 (39)  
BMI
    Less than 18 (%) 5 (4.1)* 46 (6.8) 0.3 34 (6.8) 12 (6.7) 1.0
    18.5 to 24.9 (%) 72 (58.5)* 416 (61.3) 0.6 321 (64.1) 95 (53.4) 0.015
    25 to 29.9 (%) 28 (22.8)* 139 (20.5) 0.5 100 (20.0) 39 (21.9) 0.6
    30 or more (%) 18 (14.6)* 78 (11.5) 0.4 46 (9.2) 32 (18.0) 0.0025

 

*Available for 123 subjects with only one recorded BMI.
 

MI Category Less Than 18.5 18.5 to 24.9 25 to 29.9 30 or More
Initial BMI (N=679) 46 (6.8%) 416 (61.3%) 139 (20.5%) 78 (11.5%)
Follow-up BMI (N=679) 26 (3.8%) 390 (57.4%) 164 (24.2%) 99 (14.6%)
P-value 0.02 0.17 0.11 0.1
BMI increase two points or more* 24/46 (52.2%) 88/416 (21.2%) 31/139 (22.3%) 17/78 (21.8%)
BMI decrease two points or more* 1/46 (2.2%) 20/416 (4.8%) 25/139 (18.0%) 18/78 (23.1%)
BMI change less than two points* 21/46 (45.6) 308/416 (74%) 83/139 (59.7%) 43/78 (55.1%)

 

*A BMI change of two points or greater was considered statistically significant.

Other Findings

  • In the poor adherence group, there were significantly fewer normal weight patients (53.4% vs. 64.1%, P=0.015), and significantly more obese patients (18.0% vs. 9.2%, P=0.0025)
  • In comparison to the regional population of the Northeast United States, obtained from NHIS 2007 data, significant differences were seen at all BMI categories:
    • The celiac population was significantly more likely to be underweight (6.8% vs 2.3%, P<0.0001) or normal weight (61.3% vs. 38.9%, P<0.0001) and significantly less likely to be overweight (20.5% vs. 34.8%, P<0.0001) or obese (11.5% vs. 24.0%, P<0.0001) compared with population data.
  • Individual patients' follow-up BMIs were statistically higher than initial BMIs (mean 24.6 vs. 24.0, P<0.001)
  • The drop in the total percent of underweight patients from baseline to follow-up (6.8% to 3.8%) was statistically significant (P=0.02)
  • A BMI change of two points or greater is considered significantly significant:
    • 52.2% of those who were underweight at diagnosis demonstrated a BMI increase of at least two points
    • 21.2% increased their BMI by more than two points, compared to only 4.8% who decreased by more than two BMI points (P=0.0001).
  • The poorly adherent group showed an increased tendency towards weight loss compared with those with good adherence (15% vs. 8%, P=0.01).
  • The increased baseline prevalence of obesity seen in patients with poor GFD adherence compared with good GFD adherence on initial evaluation (18% vs. 9.2%, P=0.0025) remained highly significant at follow-up (21.9% vs. 12.0%, P=0.0019)
  • Sub-group analyses were performed to determine if timing of BMI measurement from the time of diagnosis made a difference in weight category. Increase in weight was directly correlated with increasing time between BMI measurements, suggesting ongoing weight gain in many individuals.
Author Conclusion:
The significant proportion of patients who were overweight or obese at baseline, combined with the large number of celiac patients who gain excess weight on the GFD to become overweight or obese, indicate that weight maintenance counseling should be an integral part of celiac dietary education.
Funding Source:
Other: not described
Reviewer Comments:
Some questions regarding the article:
  • What criteria did the celiac dietitians use to determine adherence score?
  • Were food diaries used?
  • Were all patients weighed the same (e.g., in light clothing without shoes)?
  • Was amount of exercise or physical activity documented?
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) N/A
 
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? N/A
  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? 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? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  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.) 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? Yes
  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? N/A
  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? ???
  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? 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? 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? No
  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)? No
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? Yes