title: Diagnostic testing for celiac disease among patients with abdominal symptoms: a systematic review.
abstract: BACKGROUND
  The symptoms and consequences of celiac disease usually resolve with a lifelong gluten-free diet. However, clinical presentation is variable and most patients presenting with abdominal symptoms in primary care will not have celiac disease and unnecessary diagnostic testing should be avoided.
  
  
  OBJECTIVE
  To summarize evidence on the performance of diagnostic tests for identifying celiac disease in adults presenting with abdominal symptoms in primary care or similar settings.
  
  
  METHODS
  A literature search via MEDLINE (beginning in January 1966) and EMBASE (beginning in January 1947) through December 2009 and a manual search of references for additional relevant studies.
  
  
  METHODS
  Diagnostic studies were selected if they had a cohort or nested case-control design, enrolled adults presenting with nonacute abdominal symptoms, the prevalence of celiac disease was 15% or less, and the tests used included gastrointestinal symptoms or serum antibody tests.
  
  
  METHODS
  Quality assessment using the Quality Assessment of Diagnostic Accuracy Studies tool and data extraction were performed by 2 reviewers independently. Sensitivities and specificities were calculated for each study and pooled estimates were computed using bivariate analysis if there was clinical and statistical homogeneity.
  
  
  RESULTS
  Sixteen studies were included in the review (N = 6085 patients). The performance of abdominal symptoms varied widely. The sensitivity of diarrhea, for example, ranged from 0.27 to 0.86 and specificity from 0.21 to 0.86. Pooled estimates for IgA antiendomysial antibodies (8 studies) were 0.90 (95% confidence interval [CI], 0.80-0.95) for sensitivity and 0.99 (95% CI, 0.98-1.00) for specificity (positive likelihood ratio [LR] of 171 and negative LR of 0.11). Pooled estimates for IgA antitissue transglutaminase antibodies (7 studies) were 0.89 (95% CI, 0.82-0.94) and 0.98 (95% CI, 0.95-0.99), respectively (positive LR of 37.7 and negative LR of 0.11). The IgA and IgG antigliadin antibodies showed variable results, especially for sensitivity (range, 0.46-0.87 and range, 0.25-0.93, respectively). One recent study using diamidated gliadin peptides showed good specificity (> or = 0.94), but evidence is limited in this target population.
  
  
  CONCLUSIONS
  Among adult patients presenting with abdominal symptoms in primary care or other unselected populations, IgA antitissue transglutaminase antibodies and IgA antiendomysial antibodies have high sensitivity and specificity for diagnosing celiac disease.
authors.affiliation: Arthritis Research UK National Primary Care Centre, Primary Care Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK. d.van.der.windt@cphc.keele.ac.uk
authors.forename: Daniëlle A W M
authors.initials: DA
authors.lastname: van der Windt
authors.forename: Petra
authors.initials: P
authors.lastname: Jellema
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Mulder
authors.forename: C M Frank
authors.initials: CM
authors.lastname: Kneepkens
authors.forename: Henriëtte E
authors.initials: HE
authors.lastname: van der Horst
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D002446:Celiac Disease / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D003938:Diagnostic Techniques, Digestive System; D003967:Diarrhea / Q000209:etiology; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D011320:Primary Health Care; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D007070:Immunoglobulin A