Spencer D Dorn1, David B Matchar. 1. Division of Gastroenterology and Hepatology, University of North Carolina, CB#7080, Chapel Hill, NC 27599, USA. sdorn@med.unc.edu
Abstract
OBJECTIVE: To compare strategies for diagnosing celiac disease (CD). METHODS: A decision analytic model was used to compare five strategies on diagnostic performance and costs. RESULTS: First, tTG screening alone is the least costly strategy ($22/individual). While the NPV is high (99.8%), the PPV is low (63.4%). Second, if tTG-positive patients undergo esophagogastroduodenoscopy (EGD) to confirm CD, the PPV increases to 100% ($2,237/false-positive diagnosis avoided). Third, if EGDs are restricted to only those who are both tTG and HLA DQ2/8 positive, costs are slightly reduced ($59 vs. $63/individual), while PPV and NPV remain unchanged. Fourth, screening tTG-negative patients for IgA deficiency increases the NPV to 99.9% ($32,605/false-negative diagnosis avoided). Sensitivity analyses revealed that as the prevalence of CD increases, the cost of avoiding a false-positive diagnosis by adding EGD to the tTG alone strategy increases considerably. CONCLUSIONS: When the pre-test probability of CD is low, patients with positive tTG serology should undergo EGD with biopsy-either directly or after positive screening for HLA DQ2/8-to confirm CD. As the pre-test probability of CD increases, the added cost of EGD should be weighed against the consequences of a false-positive diagnosis. Routinely screening for IgA deficiency in order to avoid a false-negative diagnosis is quite costly.
OBJECTIVE: To compare strategies for diagnosing celiac disease (CD). METHODS: A decision analytic model was used to compare five strategies on diagnostic performance and costs. RESULTS: First, tTG screening alone is the least costly strategy ($22/individual). While the NPV is high (99.8%), the PPV is low (63.4%). Second, if tTG-positive patients undergo esophagogastroduodenoscopy (EGD) to confirm CD, the PPV increases to 100% ($2,237/false-positive diagnosis avoided). Third, if EGDs are restricted to only those who are both tTG and HLA DQ2/8 positive, costs are slightly reduced ($59 vs. $63/individual), while PPV and NPV remain unchanged. Fourth, screening tTG-negative patients for IgA deficiency increases the NPV to 99.9% ($32,605/false-negative diagnosis avoided). Sensitivity analyses revealed that as the prevalence of CD increases, the cost of avoiding a false-positive diagnosis by adding EGD to the tTG alone strategy increases considerably. CONCLUSIONS: When the pre-test probability of CD is low, patients with positive tTG serology should undergo EGD with biopsy-either directly or after positive screening for HLA DQ2/8-to confirm CD. As the pre-test probability of CD increases, the added cost of EGD should be weighed against the consequences of a false-positive diagnosis. Routinely screening for IgA deficiency in order to avoid a false-negative diagnosis is quite costly.
Authors: M Zarkadas; A Cranney; S Case; M Molloy; C Switzer; I D Graham; J D Butzner; M Rashid; R E Warren; V Burrows Journal: J Hum Nutr Diet Date: 2006-02 Impact factor: 3.089
Authors: K H Long; A Rubio-Tapia; A E Wagie; L J Melton; B D Lahr; C T Van Dyke; J A Murray Journal: Aliment Pharmacol Ther Date: 2010-04-08 Impact factor: 8.171