Clinical utility of serologic testing for celiac disease in asymptomatic patients: an evidence-based analysis.
OBJECTIVE
The objective of this evidence-based analysis was to evaluate the clinical utility of serologic testing for celiac disease in asymptomatic individuals presenting with one of the non-gastrointestinal conditions evaluated in this report. The clinical utility was based on the effects of a gluten-free diet (GFD) on outcomes specific to each of these conditions. The prevalence of celiac disease in asymptomatic individuals and one of these non-gastrointestinal conditions was also evaluated.
CELIAC DISEASE: Celiac disease is an autoimmune disease characterized by a chronic inflammatory state of the proximal small bowel mucosa accompanied by structural and functional changes.  TECHNOLOGY UNDER EVALUATION:  SEROLOGIC TESTS FOR CELIAC DISEASE: There are a number of serologic tests for celiac disease available. Serologic tests are automated with the exception of the anti-endomysial antibody test, which is more time-consuming and operator-dependent than the other tests.


OBJECTIVE
What is the prevalence of asymptomatic celiac disease in patients presenting with one of the non-gastrointestinal conditions evaluated?What is the effect of the gluten-free diet on condition-specific outcomes in patients with asymptomatic celiac disease presenting with one of the non-gastrointestinal conditions evaluated?What is the clinical utility of serologic testing for celiac disease in asymptomatic patients presenting with one of the non-gastrointestinal conditions evaluated? The clinical utility was defined as the impact of the GFD on disease specific outcomes.What is the risk of all-cause mortality and lymphoma in individuals with asymptomatic celiac disease?What is the budget impact of serologic testing for celiac disease in asymptomatic subjects presenting with one of the non-gastrointestinal conditions evaluated?


METHODS



METHODS
The study population consisted of individuals with newly diagnosed celiac disease without any symptoms consistent with the disease presenting with one of the non-gastrointestinal conditions evaluated. When evaluating the risk of lymphoma and all-cause mortality, the study population consisted of asymptomatic individuals with a positive celiac disease serologic test and/or small bowel biopsy.


METHODS



METHODS
Literature searches were performed for each disease/condition evaluated between December 2010 and March 2011 using OVID MEDLINE, the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA). No restrictions for start date of search were used. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with an unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established.


METHODS
Studies, systematic reviews, and meta-analyses that assessed the effects of a GFD in patients with newly diagnosed asymptomatic celiac disease presenting with one of the non-gastrointestinal conditions evaluated. If symptoms were not reported in the study but subjects were identified through screening for celiac disease the study was included.Studies, systematic reviews, and meta-analyses that assessed the prevalence of newly diagnosed asymptomatic celiac disease in patients with one of the non-gastrointestinal conditions evaluated. If symptoms were not reported in the study but subjects were identified through screening for celiac disease the study was included.Studies, systematic reviews, and meta-analyses that evaluated the risk of all-cause mortality or lymphoma in individuals with asymptomatic celiac disease.Sample size ≥ 10.Publications in English.


METHODS
Studies that retrospectively assessed the prevalence of asymptomatic celiac disease.Studies that reported the prevalence of one of the non-gastrointestinal conditions evaluated in subjects already diagnosed with celiac disease.Studies in individuals with one of the non-gastrointestinal conditions evaluated if the condition could be explained by other causes.Studies in subjects with celiac disease and symptoms consistent with the disease. If the study included individuals with and without symptoms consistent with celiac disease and their results were analysed separately, the results in individuals without symptoms were included in the analysis.Studies in which individuals did not report any symptoms consistent with celiac disease at study start but that either retrospectively reported the presence of such symptoms after following a GFD, or that previously presented with symptoms consistent with celiac disease.Study results published in letters to the editor or comments about other studies.Studies with a sample size ≥ 10, however, in which less than 10 patients were included in the analysis.


METHODS
The effects of a GFD on disease-specific outcomes for each condition evaluated in patients with asymptomatic celiac disease was assessed. The prevalence of asymptomatic celiac disease in patients presenting with one of the conditions evaluated was also assessed.  RESULTS OF EVIDENCE-BASED ANALYSIS: Three eligible observational studies evaluated the effects of GFD on growth parameters in subjects with asymptomatic celiac disease and idiopathic short stature. Four eligible observational studies evaluated the effects of GFD on metabolic control in subjects with asymptomatic celiac disease and type 1 diabetes. Five eligible observational studies evaluated the risk of all-cause mortality and five eligible observational studies evaluated the risk of lymphoma in subjects with asymptomatic celiac disease. No eligible studies on the effects of the GFD for the other conditions evaluated were identified. Twenty-three eligible studies measured the prevalence of asymptomatic celiac disease in subjects presenting with one of the conditions evaluated.  PREVALENCE OF CELIAC DISEASE IN ASYMPTOMATIC PATIENTS: The prevalence of celiac disease in asymptomatic patients presenting with one of the conditions evaluated was analysed. Most studies also included a control group that generally consisted of individuals randomly selected from the general population. Although there was a trend to a higher prevalence of asymptomatic celiac disease in individuals with the conditions evaluated compared to the controls, it only reached statistical significance in type 1 diabetes. No eligible prevalence studies were identified in patients with amenorrhea, delayed puberty, alopecia, and depression.  THE EFFECTS OF A GLUTEN-FREE DIET ON DISEASE-SPECIFIC OUTCOMES IN PATIENTS WITH ASYMPTOMATIC CELIAC DISEASE:  THE EFFECTS OF GFD ON METABOLIC CONTROL IN PATIENTS WITH ASYMPTOMATIC CELIAC DISEASE AND TYPE 1 DIABETES: The effects of a GFD on metabolic control (HbA1c, number of hypoglycemic episodes, and changes in insulin dosage) in subjects with asymptomatic celiac disease and type 1 diabetes were evaluated. One prospective case-control study reported an increase in HbA1c levels in cases with type 1 diabetes and asymptomatic celiac disease after the introduction of a GFD, however, the clinical significance of this change is unclear. Only one eligible retrospective case-control study evaluated the effects of a GFD on hypoglycemia episodes and since there were inadequate details in the study about both the ascertainment and severity of hypoglycemia episodes in both cases and controls, it is not possible to draw conclusions regarding the effects of a GFD on hypoglycemia episodes based on this study. One prospective case-control study did not show a statistically significant change in insulin dosage between cases with type 1 diabetes and asymptomatic celiac disease and controls with type 1 diabetes either before or after the introduction of a GFD. No eligible studies that evaluated the effects of a GFD on the long-term outcomes of type 1 diabetes such as cardiovascular or renal events in patients with asymptomatic celiac disease were identified.  THE EFFECTS OF A GLUTEN-FREE DIET IN PATIENTS WITH IDIOPATHIC SHORT STATURE AND ASYMPTOMATIC CELIAC DISEASE: A total of 3 eligible studies were identified. All studies consisted of case series that compared growth parameters in subjects with asymptomatic celiac disease and idiopathic short stature before and after the celiac disease was diagnosed and the GFD was instituted. Most subjects included in the studies demonstrated an improvement in growth parameters. Compliance with the GFD was not reported in the studies. The results of the studies suggest an increase in growth velocity in pediatric patients with asymptomatic celiac disease and idiopathic short stature once a GFD is introduced.  RISK OF LYMPHOMA IN PATIENTS WITH ASYMPTOMATIC CELIAC DISEASE: One retrospective cohort study evaluated the risk of lymphoma in patients with asymptomatic celiac disease. The authors concluded that the number of events identified was low during the long follow-up period and that the risk of overall malignancies was not increased among patients with asymptomatic celiac disease.  RISK OF ASYMPTOMATIC CELIAC DISEASE IN PATIENTS WITH LYMPHOMA: Four case-control studies, one of which retrospective, evaluated the risk of asymptomatic celiac disease in patients newly diagnosed with lymphoma. One retrospective cohort study did not show an increase in the risk of lymphoma among subjects with asymptomatic celiac disease. Three prospective case-control studies did not find a statistically significant risk of asymptomatic celiac disease in patients with newly diagnosed lymphoma. (ABSTRACT TRUNCATED)