This Academy member benefit temporarily has been made public to allow all practitioners access to content that may assist in patient care during the national pandemic response. Click here for information on joining the Academy. 

CD: Quality of Life (2006)


Zarkadas M, Cranney A, Case S, Molloy M, Switzer C, Graham D, Butzner JD, Rashid M, Warren RE, Burrows V.  The impact of a gluten-free diet on adults with celiac disease:  results of a national survey.  J Hum Nutr Dietet 2006; 19:41-49. 

PubMed ID: 16448474
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To determine the impact of having to follow a gluten-free diet on the quality of life of individuals with celiac disease, to assess compliance with the diet and identify difficulties experienced with following such a diet and to evaluate sources of information about the disease and its treatment.
Inclusion Criteria:
Members of the Canadian Celiac Association, 16 years and older.
Exclusion Criteria:

Excluded if under 16 years of age.

Description of Study Protocol:


 Biopsy-proven adult members of the Canadian Celiac Association.


 Cross-Sectional Study.

Blinding used (if applicable)

 Not applicable.

Intervention (if applicable)

 Mailed out survey.

Statistical Analysis

 Logic checks were performed using cross-tabulations for key variables.  The proportion of respondents choosing different options was calculated for each question.  Where relevant, Student's t test for continuous variables and chi-square tests for discrete variables were performed when comparing 2 groups.

Data Collection Summary:

Timing of Measurements

Canadian Celiac Health Survey developed as mailed out survey with 76 questions.  Questionnaires mailed out in October 2002 and respondents asked to complete by end of the month.

Dependent Variables

  • Quality of life evaluated using the SF-12 and series of celiac-specific questions. Questionnaire reviewed by 2 international celiac disease experts

Independent Variables

  •  Gluten free diet not defined

Control Variables


Description of Actual Data Sample:

Initial N: 5240 members, 3408 (65%) response rate after one mail-out.  504 excluded from analysis for not having biopsy-proven celiac disease and 55 excluded for not completing questionnaire adequately

Attrition (final N):  2681 adults responded, 74.5% females.

Age:  mean age 56 years (range 16 - 90)

Ethnicity:  Not mentioned 

Other relevant demographics:  mean age at diagnosis was 46 years, mean duration of disease after diagnosis was 10 years

Anthropometrics (e.g., were groups same or different on important measures)

Location:  Canada, respondents from all 10 provinces


Summary of Results:



All of the time (%) Most of the time (%) Some of the time (%) Never (%) Not Applicable

Brought gluten-free foods while travelling


22 19



Avoided restaurants


27 48



Had difficulty finding good quality gluten-free foods 8 22 53 17 --
Had difficulty finding gluten-free foods 6 19 60 15 --
Could not determine if foods were gluten-free 5 13 67 15 --
Avoided travelling 3 10 25 62 0

Worried about staying in a hospital because of celiac disease


5 14



Felt left out of meal invitations because of celiac disease 2 6 28 63 1.0

 Other Findings

 The SF-12 summary scores were similar to normative Canadian data, but were significantly lower for females and newly diagnosed patients.

Respondents reported following a gluten-free diet (90%), improvement on the diet (83%), and difficulties following the diet (44%), which included determining if foods were gluten-free (85%), finding gluten-free foods in stores (83%), avoiding restaurants (79%), and avoiding travel (38%).

Most common reactions to consumed gluten (reported by 73%) included pain (80%), diarrhea (77%), bloating (74%), fatigue (40%), nausea (26%), headache (23%), itchy skin (21%), constipation (15%), insomnia (12%) and mouth ulcers (8%).

The most frequent responses regarding what would contribute most to improving their lives were early diagnosis (60.5%), better food labeling (52%), more gluten-free foods in the supermarket (39.8%), more gluten-free choices on restaurant menus (27.5%) and better dietary counseling (12.9%).

Excellent information on celiac disease and its treatment was provided by the Canadian Celiac Association (64%), gastroenterologists (28%), dietitians (26%) and family doctor (12%).

Author Conclusion:
Although the quality of life scores using the SF-12 were similar to those of the general Canadian population, the reasons for lower scores among women need further study.  Quality of life in those with celiac disease could be increased with early diagnosis, increased availability of gluten-free foods, improved food labelling, and better dietary instruction.  Education of physicians and dietitians about celiac disease and its treatment is essential.
Funding Source:
Foundation associated with industry:
Reviewer Comments:
65% response rate.  Only members of the association included.  Questionnaire not tested for reliability.
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) N/A
  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? 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? 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? 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? 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? N/A
  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? 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? N/A
  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)? N/A
  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