EAL

CD: Bone Density (2006)

Citation:

Mora S, Barera G, Beccio S, Menni L, Proverbio MC, Bianchi C, Chiumello G. A prospective, longitudinal study of the long-term effect of treatment on bone density in children with celiac disease. J Pediatr 2001; 139: 516-521.

PubMed ID: 11598597

Study Design:

Non-Randomized Controlled Trial

Class:

C - Click here for explanation of classification scheme.

Quality Rating:

POSITIVE: See Quality Criteria Checklist below.

Research Purpose:

To evaluate the impact of a long-term gluten-free diet, initiated during childhood, on bone mineral density.

Inclusion Criteria:

Eligible for the study were patients who had participated in a different longitudinal study. Diagnosis of celiac disease was made according to the recommendations of the European Society of Pediatric Gastroenterology and Nutrition. All patients showed positive anti-endomysium antibodies and mucosal atrophy on small bowel biopsy, with clinical improvement following the initiation of dietary treatment. All patients had been on a gluten-free diet since diagnosis.

Exclusion Criteria:

Excluded if they had a history of chronic illness; if they had sustained 1 or more fractures; if they had taken any medication, hormone, vitamin preparation or calcium supplements regularly.

Description of Study Protocol:

Recruitment

Recruited from a different longitudinal survey completed elsewhere.

Design

Nonrandomized Clinical Trial.

Blinding used (if applicable)

No blinding used.

Intervention (if applicable)

Gluten-free diet for 4.3 +/- 0.6 years. No calcium or vitamin supplements.

Statistical Analysis

Data expressed as mean +/- SD. All statistical analyses conducted at the alpha = 0.05 level and were two-tailed. Multivariate analyses were performed to evaluate the differences between patients with celiac disease and controls, after controlling for confounding variables. Bone mineral content, bone area and bone mineral density differences were computed from the values measured after the first year of gluten-free diet and after longer duration of treatment; annualized increments were then calculated. The bone densitometry data obtained from the control subjects were plotted against age. Simple regression analysis was performed, and the annual increments of spinal and total bone mineral content, bone area and bone mineral density were obtained.

Data Collection Summary:

Timing of Measurements

Bone density measured at diagnosis, after 1 year of gluten-free diet, and after 4.3 +/- 0.6 years of gluten-free diet. Intact parathyroid hormone, bone-specific alkaline phosphatase, and N-terminal telopeptide of type I collagen also measured.

Dependent Variables

Bone mineral measurements made with dual-energy x-ray absorptiometer. Bone mineral content, bone area and bone mineral areal density measured at L2 - L4 vertebrae and in whole skeleton
Blood and urine specimens collected between 10 am - noon to minimize effect of circadian rhythm on excretion of bone formation and bone resorption markers
Intact parathyroid hormone measured by immunoradiometric assay
Bone-specific alkaline phosphatase measured in serum as bone formation marker with commercial immunoassay
Urine concentration of N-terminal telopeptide of type I collagen as bone resorption index measured by ELISA
Urine creatinine measured by colorimetric method

Independent Variables

Gluten-free dietary compliance monitored through measurements of serum anti-tissue transglutaminase antibodies. Human tissue transglutaminase complementary DNA was cloned and translated in vitro and a protein-A-based radio-binding assay was used for anti-tissue transglutaminase antibodies.

Description of Actual Data Sample:

Initial N: 25 original patients in other longitudinal study. 19 patients with celiac disease agreed to participate. 211 healthy children as controls (101 female, 110 male).

Attrition (final N): 19 patients, 211 controls.

Age: 14.2 +/- 2.6 years. Controls aged 9.5 - 19.2 years.

Ethnicity: Controls were white.

Other relevant demographics: Mean weight was 42.7 +/- 10.7 kg, mean height was 151.5 +/- 12.0 cm. Mean weight and height of controls were 48.8 +/- 14.3 kg and 156.3 +/- 14.2 cm.

Location: Italy

Summary of Results:

	At Diagnosis	Short-Term GFD (1.1 +/- 0.3 years)	Long-Term GFD (4.3 +/- 0.6 years)
Age (years)	9.6 +/- 0.7	10.8 +/- 0.7	14.5 +/- 0.6
Spinal Bone Mineral Content (g)	18.0 +/- 1.9	21.3 +/- 2.5	29.5 +/- 2.8
Spinal Bone Area (cm2)	24.4 +/- 1.2	26.2 +/- 1.5	31.5 +/- 1.4
Spinal Bone Mineral Density (g/cm2)	0.713 +/- 0.042	0.769 +/- 0.042	0.904 +/- 0.050
Total-Body Bone Mineral Content (g)	1077.5 +/- 96.5	1311.6 +/- 107.5	1717.4 +/- 117.1
Total-Body Bone Area (cm2)	1207.2 +/- 81.3	1383.2 +/- 80.2	1674.1 +/- 73.6
Total-Body Bone Mineral Density (g/cm2)	0.874 +/- 0.022	0.913 +/- 0.026	1.007 +/- 0.028

Other Findings

At the time of diagnosis, spinal bone mineral density values of patients with celiac disease was significantly lower (P = 0.03) than those of controls. The mean difference between groups, after controlling for age, sex and weight was 0.027 g/cm2. After controlling for confounding variables, spinal bone mineral content were reduced on average by 2.9 g (P = 0.03). Spinal bone area measurements were also significantly lower (1.05 cm2, P = 0.05).

Total-body bone mineral density measurements at diagnosis were also significantly lower in patients than controls (0.022 g/cm2, P = 0.04). Total-body bone mineral content significantly lower in patients than controls (44.3 g, P = 0.04). Total-body bone area values also significantly lower than in controls (32.3 cm2, P = 0.045).

Bone mineral measurements were repeated after 1.1 +/- 0.3 and 4.3 +/- 0.6 years of gluten-free diet and spinal and total-body values did not differ from controls.

Mean annual increment of spinal bone mineral density during the first year was 0.061 g/cm2, whereas total-body bone mineral density increased by 0.042 g/cm2. During subsequent years of treatment, bone mineral density increased at a lower rate (0.042 g/cm2/year spinal, 0.030 g/cm2/year total-body).

None of the patients on a gluten-free diet showed elevated values of intact parathyroid hormone (average concentration 15.7 +/- 4.2 pg/mL, reference values 10 - 60 pg, mL).

Patients on a gluten-free diet had bone-specific alkaline phosphatase (110.2 +/- 67.2 U/L, P = 0.0088) and N-terminal telopeptide of type I collagen levels (261.9 +/- 187.8 nmol bone collagen equivalents/mmol creatinine, P = 0.01) that were significantly higher than those of control subjects.

The anti-tissue transglutaminase antibody assay detected positive levels in 9 patients. Levels of bone-specific alkaline phosphatase (P = 0.035) and N-terminal telopeptide of type I collagen (P = 0.05) were significantly higher in patients with good compliance with the gluten-free diet, compared with those having poorer compliance.

Author Conclusion:

This study provides evidence for complete recovery of bone density after about a year of gluten-free diet in children and adolescents with celiac disease and for maintenance of normal body mineral density values after long-term treatment. This study shows that bone mineral content, bone area, and bone mineral density improve significantly with a gluten-free diet. The difference between patients with positive antibodies and those with negative antibodies was statistically significant. This finding could indicate that bone metabolism may be affected by immunologic alterations, which could impair normal function of bone cells, and ultimately affect bone mineralization.

Funding Source:

University/Hospital:

University of Milan (Italy)

Reviewer Comments:

Compliance to gluten-free diet was monitored and data evaluated between groups.

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?	N/A
	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?	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?	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?	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?	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?	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?	N/A
	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