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CD: Quality of Life (2006)


Usai P, Minerba L, Marini B, Cossu R, Spada S, Carpiniello B, Cuomo R, Boy MF.  Case control study on health-related quality of life in adult celiac disease.  Digest Liver Dis 2002; 34 (8): 547-552.

PubMed ID: 12502210
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate whether health-related quality of life in adult celiac disease is related to severity of illness in terms of number of symptoms at diagnosis, compliance to gluten-free diet, and presence of associated diseases.
Inclusion Criteria:

Diagnosis of celiac disease based on clinical, serological, and histological criteria.

Exclusion Criteria:
Two excluded due to complaint of major symptoms and silent disease.
Description of Study Protocol:


Consecutive adult celiac patients at Cagliari University between September and November 1998.  Controls selected from staff (physicians, nurses and technicians) of Dept of Internal Medicine of Cagliari University.



Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Gluten-free diet for at least 2 years.

Statistical Analysis

Raw scores of SF-36 were calculated from patient's answers and transformed into a score ranging from 0 - 100 (0 = marked dysfunction, 100 = no dysfunction) according to specific algorithm.  Mean score, standard error and 95% confidence intervals obtained for each domain were calculated.

Data Collection Summary:

Timing of Measurements

Subjected health status measured in both patients and controls.  All patients screened for IgA anti-endomysial and anti-gliadin antibodies for dietary compliance.  Patients with positive response to AgA-A and/or EmA were considered eligible for intestinal biopsy.  Medical records also reviewed at the time of diagnosis.

Dependent Variables

  • Subjective health status measured by Short Form 36 Health Survey (SF-36)
  • IgA EmA determined through indirect immunofluorescence
  • AGA-A antibodies measured through ELISA
  • Specimens from repeat intestinal biopsy classified according to Marsh & Crowe

Independent Variables

  • Gluten-free diet:  at time of interview, degree of adherence to gluten-free diet evaluated, graded as complete (no intake of gluten), adhesion (intake of gluten 2 - 3 times a week or month), or none (continuous intake of gluten).

Control Variables


Description of Actual Data Sample:

Initial N: 68 celiac patients, 54 female, 14 male.  136 sex-, age- and ethnic group-matched healthy controls.

Attrition (final N):  See above.

Age:  Patients:  range 18 - 74 years, mean 46 years.  Controls:  range 18 - 75 years, mean 47 years.

Ethnicity:  Not mentioned. 

Other relevant demographics:  Not mentioned.

Anthropometrics:  Age-, sex- and ethnic group-matched controls.

Location:  Italy 


Summary of Results:

Other Findings

Of celiac patients interviewed, 39 (59.1%) reported strict adherence to diet, 25 (37.9%) only partial adhesion, and 2 (3%) admitted non-compliance to diet.

Of the 39 reporting total dietary adherence, 2 (5%) resulted positive for antigliadin antibodies (AGA-A) and/or EmA.  24 of the 25 patients (96%) declaring positive adhesion showed positive AGA-A and/or EmA antibodies.

All 26 patients with positive AGA-A or EmA showed partial villous atrophy and crypt hyperplasia on small bowel biopsy.

Patients obtained worse scores with respect to healthy controls at all domains of SF-36 (p < 0.05).  Compliers showed better results than non-compliers.

Poorly compliant patients obtained significantly lower scores than compliant subjects for mental health and social functioning domains (p < 0.05); their scores for the remaining domains were lower, but this difference did not reach statistical significance.

The lowest scores at SF-36 were obtained in patients with more than 6 symptoms at diagnosis, mostly in non-compliers, the highest in compliers with less than 6 symptoms.

Patients with 2 or more associated diseases (n=20, compliers n=13/20, 65%) scored significantly worse than patients with only 1 associated disease (n=22, compliers n=14/22, 64%) in general health, mental health, vitality, bodily pain, emotional role, physical role, and physical functioning domains, while no significant difference was found between patients without any associated disease and patients with only 1 associated disease.

Author Conclusion:
The importance of gluten-free diet in clinical management of celiac disease is confirmed by results of the present study; moreover, the results seem to indicate that a complex interplay of factors should be taken into account in evaluating health-related quality of life in celiac disease.  Our results also suggest that factors other than gluten-free diet may influence the health-related quality of life of celiac patients, as suggested by the lower scores at SF-36 in patients affected by more than 6 symptoms.
Funding Source:
University/Hospital: Cagliari University (Italy), University of Naples Federico II (Italy)
Reviewer Comments:
Dietary compliance assessed through antibody measurement.
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? 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? Yes
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.) Yes
  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? 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? 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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? Yes
  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)? Yes
  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