Consequences of testing for celiac disease.

Population screening studies have identified that up to two thirds of celiac disease (CD) cases are asymptomatic. The aim of this study was to conduct a systematic review of the expected consequences of testing for CD in the following populations: (1) patients with symptoms suggestive of CD, (2) asymptomatic at-risk populations, and (3) general population. Standard systematic review methodology was used. A comprehensive literature search was conducted in MEDLINE (1996-2003), EMBASE (1974-2003), CAB (1972 forward), PsychINFO (1840-2003), AGRICOLA (1970-2003), and Sociological Abstracts (1963 forward); searches were conducted in December 2003. Pooled summary estimates were not calculated. The majority of the included studies were before-after studies, case control, or retrospective cohorts. The quality of evidence for the before-after studies is weaker. The overall strength of the evidence for this issue was fair to good. This area of research is relatively new, and further high-quality studies are required. The consequences of testing for celiac disease in symptomatic individuals appears to have a positive impact on patient-relevant outcomes. The data are less clear for those with silent CD or those with lower grade histologic lesions in small bowel biopsy. The literature suggests that compliance is less than ideal in these individuals, especially if diagnosed when adults. Long-term outcomes have not been extensively studied in those with silent CD.

The diagnostic accuracy of serologic tests for celiac disease: a systematic review.

Clinicians are increasingly utilizing noninvasive serologic tests for the diagnosis and screening of celiac disease (CD). The aim of this study was to conduct a systematic review of the diagnostic performance of serologic tests for the diagnosis and screening of CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. A weighted mean of the sensitivity and specificity along with 95% confidence intervals and summary receiver operating characteristic (ROC) curves were calculated. The pooled specificity of endomyseal antibody (EMA)-monkey esophagus (ME) or EMA-human umbilical cord (HU) was close to 100% in adults and children. The pooled specificity of transglutaminase antibody (tTG)-guinea pig (GP) and tTG-human recombinant (HR) were between 95% and 99%. IgA-EMA-ME demonstrated sensitivities of 96% and 97% in children and adults, respectively. EMA-HU demonstrated a similar sensitivity of 97% in children but 90% in adults. The pooled sensitivity of tTG-GP in adults and children was 90% and 93%, respectively. The sensitivity of tTG-HR was 98% and 96%, respectively. The performance of antigliadin antibody was inferior to that of EMA and tTG. EMA and tTG offer high sensitivity and specificity. The sensitivity of these tests appears to be lower than reported when milder histologic grades are used to define CD (below 90%). If true, the nearly perfect negative predictive value of these tests would drop. The positive predictive value of these tests is likely lower than reported when the tests are applied in low-prevalence populations.

The prevalence of celiac disease in average-risk and at-risk Western European populations: a systematic review.

Until recently, celiac disease (CD) was felt to be a rare disease in the United States. The aim of this study was to conduct a systematic review of the prevalence of CD in general Western populations and in populations at high risk for CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. Qualitative and quantitative prevalence estimates were produced after assessing study heterogeneity. The prevalence of CD in general Western populations is close to 1% and is somewhat higher in certain Western European populations. The prevalence of CD in populations at risk for CD is as follows: 3%-6% in type 1 diabetic patients, up to 20% in first-degree relatives, 10%-15% in symptomatic iron-deficiency anemia (IDA), 3%-6% in asymptomatic IDA, and 1%-3% in osteoporosis. The prevalence of CD in patients suspected of having CD varied depending on the reasons for suspecting CD and on whether the study was conducted in a referral center. In general, the prevalence ranged from 5% to 15%, but was up to 50% in symptomatic patients evaluated in a tertiary referral center. CD is a common medical condition. The prevalence is higher still in high-risk groups. Clinicians in a variety of specialties should have a high index of suspicion for the diagnosis of CD and in particular need to pay close attention to the identified high-risk groups.