Self-reported dietary fructose intolerance in irritable bowel syndrome: Proposed diagnostic criteria

Abstract

Aim: To study the criteria for self-reported dietary fructose intolerance (DFI) and to evaluate subjective global assessment (SGA) as outcome measure.

Methods: Irritable bowel syndrome (IBS) patients were randomized in an open study design with a 2 wk run-in on a habitual IBS diet, followed by 12 wk with/without additional fructose-reduced diet (FRD). Daily registrations of stool frequency and consistency, and symptoms on a visual analog scale (VAS) were performed during the first 4 wk. SGA was used for weekly registrations during the whole study period. Provocation with high-fructose diet was done at the end of the registration period. Fructose breath tests (FBTs) were performed. A total of 182 subjects performed the study according to the protocol (88 FRD, 94 controls).

Results: We propose a new clinically feasible diagnostic standard for self-reported fructose intolerance. The instrument is based on VAS registrations of symptom relief on FRD combined with symptom aggravation upon provocation with fructose-rich diet. Using these criteria 43 of 77 patients (56%) in the present cohort of IBS patients had self-reported DFI. To improve the concept for clinical evaluation, we translated the SGA scale instrument to Norwegian and validated it in the context of the IBS diet regimen. The validation procedures showed a sensitivity, specificity and κ value for SGA detecting the self-reported DFI group by FRD response within the IBS patients of 0.79, 0.75 and 0.53, respectively. Addition of the provocation test yielded values of 0.84, 0.76 and 0.61, respectively. The corresponding validation results for FBT were 0.57, 0.34 and -0.13, respectively.

Conclusion: FRD improves symptoms in a subgroup of IBS patients. A diet trial followed by a provocation test evaluated by SGA can identify most responders to FRD.

Trial registration: ClinicalTrials.gov NCT00555191.

Keywords: Breath test; Dietary restriction; Fructose malabsorption; Functional bowel disease; Sugar intolerance.

Figures

Figure 1

Scale and precision of the subjective global assessment measure. At 4 wk, the change in VAS registration (compared to pre-registration values) was calculated. Box and whiskers plot of VAS change in the different subcategories of SGA at 4 wk. It is noted that the scale is not entirely linear, with best discrimination in the left part of the plot, while the right part shows smaller VAS differences between groups. SGA: Subjective global assessment; VAS: Visual analog scale.

Figure 2

Subjective global assessment of irritable bowel syndrome-related symptoms during the whole study. Mean registration (95%CI) for study groups. The control group showed stable mean value during the 2 + 12 wk registration. The mean effect of FRD was marked, showing stable improvement of symptom rating during the whole study. The SGA ratings were: 1: Completely relieved; 2: Considerably relived; 3: Somewhat relieved; 4: Unchanged; 5: Worse. FRD: Fructose-reduced diet; SGA: Subjective global assessment; IBS: Irritable bowel syndrome.

Figure 3

Visual analog scale registrations of irritable bowel syndrome-related symptoms during the first 2 + 4 wk. Mean registration (95%CI) for the study groups. FRD: Fructose-reduced diet; VAS: Visual analog scale; IBS: Irritable bowel syndrome.