Determination of Optimal Eosinophil Thresholds for Diagnosis of Eosinophilic Gastritis and Duodenitis: A Pooled Analysis of 4 Prospective Studies.

OBJECTIVES: Consensus is lacking regarding the number of eosinophils (eos) required for diagnosis of eosinophilic gastritis (EoG) and eosinophilic duodenitis (EoD). Additionally, thresholds that require multiple high-power fields (hpfs) may not be practical for clinical use, resulting in delayed or missed diagnoses. This pooled analysis of 4 prospective studies assessed thresholds for multiple and single hpfs used to diagnose EoG and EoD.

METHODS: Studies included the phase 2 ENIGMA1, the phase 3 ENIGMA2, an EoG/EoD prevalence study, and a healthy volunteer study. Eosinophils were quantified in the epithelium and lamina propria for controls and symptomatic participants. Symptomatic participants were further divided by histologic diagnosis of EoG/EoD. Peak eos counts were assessed, and area under the receiver operating characteristic (AUROC) curve was analyzed to identify eos cutoffs for detection of EoG/EoD using the Youden index and sensitivity and specificity equality approaches.

RESULTS: Based on the highest specificity analysis in 740 patients, the optimal eos threshold was determined to be 20 eos/hpf in 5 gastric hpfs for EoG (71% sensitivity; 94% specificity) and 33 eos/hpf in 3 duodenal hpfs for EoD (49% sensitivity; 100% specificity). For single-field analysis, the optimal eos thresholds were 33 eos/hpf (EoG) and 37 eos/hpf (EoD), both corresponding to 93% sensitivity and 93% specificity.

CONCLUSIONS: Highly specific single gastric and duodenal hpf thresholds may have more clinical applicability than thresholds requiring multiple hpfs and could better facilitate development of practical histopathologic guidelines to aid pathologists and clinicians in the detection and diagnosis of EoG and/or EoD.