Constipation Symptoms Differ Between Individuals With Irritable Bowel Syndrome With Constipation and Chronic Idiopathic Constipation

Abstract

Introduction: We characterized constipation symptoms among individuals with irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC). Methods: Adults (>18 years of age) were identified from a nationwide sample of over 70,000 US adults meeting modified Rome III criteria for IBS-C or CIC. Dimensions of the constipation experience were assessed using the validated GI-PROMIS® questionnaire administered by the novel ehealth app MyGI-Health. Question items were developed using systematic literature review followed by open-ended questions in patient focus groups. Question items were mapped onto a matrix according to pre-defined dimensions within the conceptual framework of constipation symptoms. Content validity, patient understanding, and reliability were established in semistructured interviews and a subsequent multi-center survey. Odds ratios (OR) with 95% confidence intervals (CI) were calculated using logistic regression to evaluate responses in IBS-C relative to CIC which were previously mapped onto five-point response scales. Differences in GI-PROMIS scores (range=0-100, mean=50, standard deviation=10) were assessed using one-way ANOVA. Results: 970 individuals met eligibility criteria (275 with IBS-C; 734 with CIC). Demographics were similar except for education, marital status, employment status, and income. GI-PROMIS scores, as a composite measure of frequency and severity, were higher in IBS-C (score=75) compared to CIC (score=68) (p=0.01). Among first-order individual question items within the constipation symptom domain, there were differences in constipation symptoms reported by IBS-C and CIC. IBS-C patients had more hard or lumpy stools, rectal pain frequency, and need for digitation though overall bothersomeness was similar between the groups (Table). No items in the instrument favored more severe or frequent symptoms in the CIC cohort.Table: Table. Responses to constipation question items characterizing the constipation experience in IBS-C and CICConclusion: GI-PROMIS scores are higher in IBS-C compared to CIC individuals. Given the striking overlap between symptoms in patients with IBS-C and CIC, it is reasonable to hypothesize that IBS-C and CIC reside upon a spectrum of disease severity with CIC patients representing the less severely affected end of the spectrum and IBS-C representing the more severely affected end of the spectrum.