CD: Nutritional Adequacy (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To investigate the prevalence of vitamin B12 deficiency in patients with untreated celiac disease.

Inclusion Criteria:
Biopsy-proven celiac disease patients.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:

Recruitment

Consecutive biopsy-proven celiac disease patients between September 1997 and February 1999.

Design

Cohort Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Gluten-free diet for a median of 4 months (range 2 - 13 months).

Statistical Analysis

Statistical analysis not described.

Data Collection Summary:

Timing of Measurements

Blood samples measured before and after gluten-free diet.

Dependent Variables

  • Full blood count
  • Serum vitamin B12
  • Red blood cell folate
  • Plasma ferritin, iron, transferrin and transferrin saturation
  • Celiac autoantibodies (IgA antigliadin and IgA antiendomysium)
  • Intrinsic factor antibodies and Schilling test part 1 in vitamin B12 deficient patients

Independent Variables

  • Gluten-free diet for a median of 4 months (range 2 - 13 months)

  • Compliance measured through antibody testing

Control Variables

 

Description of Actual Data Sample:

Initial N: 39 patients, 32 women, 7 men

Attrition (final N):  39 patients

Age: median age 48 years, range 22 - 77 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:

Location:  Scotland

 

Summary of Results:

Other Findings

A total of 16 (41%) patients were vitamin B12 deficient (<220 ng/L) and 16 (41%) patients (11 women and 5 men) were anemic.

Concomitant folate deficiency was present in only 5/16 (31%) of the vitamin B12 patients.

The Schilling test, performed in 10 of the vitamin B12 deficient patients, showed 5 low and 5 normal results.

Intrinsic factor testing was negative in all patients.

Although only 5 patients received parenteral vitamin B12, at follow-up the vitamin B12 results had normalized in all patients.

Red blood cell folate concentrations had also normalized in all 13 patients tested.

Acral paresthesia at presentation in 3 vitamin-deficient patients resolved after vitamin B12 replacement. 

Author Conclusion:
We conclude that vitamin B12 deficiency is common in untreated celiac disease in an unselected cohort of patients in Scotland, and that hematinic replacement - especially folate replacement - should not be prescribed without first ensuring that the patient is replete with vitamin B12.  Vitamin B12 deficiency will resolve on a gluten-free diet alone without parenteral supplementation, and such supplementation may be required only in those symptomatic for B12 deficiency.
Funding Source:
Government: Chief Scientist's Office (Scottish Executive)
Reviewer Comments:
Inclusion/exclusion criteria not well defined.  Compliance to GFD assessed through antibodies.  Statistical analysis not described.  Length of time on GFD only 2 months in some cases.
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? 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? No
  2.2. Were criteria applied equally to all study groups? ???
  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? N/A
  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? N/A
  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? 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? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? ???
  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? ???
  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? Yes
  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? N/A
  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? ???
  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? Yes
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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