PREVALENCE OF DISACCHARIDASE DEFICIENCY IN ADULTS WITH IRRITABLE BOWEL SYNDROME AND FUNCTIONAL DIARRHEA: ANALYSIS FROM A MULTICENTER, PROSPECTIVE US STUDY

Background: Disaccharidases are brush border enzymes that digest disaccharides to monosaccharides for absorption across the intestinal epithelium. Patients with disaccharidase deficiency (DD) may experience post-prandial abdominal pain, bloating, flatulence and diarrhea that can mimic irritable bowel syndrome with diarrhea (IBS-D) and functional diarrhea (FD). The US prevalence of disaccharidase deficiencies in symptomatic adults is poorly defined.

Aim: Analysis from a prospective, US, multicenter study assessing the prevalence of disaccharidase deficiency in US adult patients with IBS-D and FD.

Methods: Adult (>18 yrs) patients[SE1] [WC2] fulfilling Rome IV diagnostic criteria for IBS-D or FD were recruited at US academic medical centers. Exclusion criteria included pregnancy, lactation, severe GI or medical co-morbidities, and previous GI surgeries (excluding cholecystectomy or appendectomy). Eligible patients completed EGD with small intestinal biopsies collected from the duodenum. Biopsy samples underwent disaccharidase assay (DA) to measure enzyme activity (normal lactase: >15.4 mM/min/g; sucrase: >28.0 mM/min/g, maltase: >120.8 mM/min/g, palatinase: >9.8 mM/min/g, glucoamylase: >13.1 mM/min/g) using validated protocols at experienced reference labs (Arnold Palmer Hospital, Prometheus, and Joli Laboratories). Enrolled patients also underwent ¹³C-Sucrose breath testing (C-SBT, Metabolic Solutions).

Results: 199 patients (mean age= 46.1 years, 45% IBS-D, 55% FD, 73.5% female, 86.5% white) were enrolled and had biopsies for DD. More than a third of patients (75/199, 37.7%) had at least 1 DD. The most common DD was lactase deficiency (72/199, 36.2%). Seventeen patients (8.5%) tested positive for sucrase deficiency and 17 (8.5%) had maltase deficiency. Palatinase deficiency prevalence was 6.5% (13/199) and glucoamylase deficiency was identified in 6.2% (9/145) [Table 1]. Lactase deficiency most commonly occurred in isolation. Nineteen patients (9.5%) were identified with non-lactase deficiency, and most had multiple DDs (84% (16/19)). More than a third (7/19) had pan-DDs. The prevalence of the various DDs was consistent across sites. 29.8% (39/131) of participants had a positive C-SBT. Using disaccharide assay results as the gold standard, performance characteristics of C-SBT are listed in Table 2.

Conclusions: More than one-third of US adult patients with IBS-D or FD had at least 1 DD. Lactase deficiency was the most common DD identified and the most likely to occur in isolation. Non-lactase DD was identified in approximately 1 in 10 symptomatic patients, and was typically associated with at least one other DD. In this population, C-sucrose breath testing had limited predictive value in the diagnosis of sucrase deficiency. DD may be an important and overlooked causes for symptoms in US patients with IBS-D or FD.