Clinical Features and Symptom Burden in Vietnamese Patients with Diarrhea-Predominant Irritable Bowel Syndrome: A Single-Center Cross-Sectional Study Using IBS-SSS and IBS-QoL Scores

Background/Objectives. Diarrhea-predominant irritable bowel syndrome (IBS-D) significantly affects patients’ quality of life (QoL). However, data on disease severity and its correlation with QoL among Vietnamese patients remain limited. This study aimed to investigate the clinical characteristics, symptom severity, and the relationship between symptom burden and quality of life in patients with IBS-D in Vietnam. Methods. A cross-sectional study was conducted on patients diagnosed with IBS-D based on the Rome IV criteria at an outpatient clinic of a tertiary hospital. Disease severity and QoL were assessed using the IBS Symptom Severity Score (IBS-SSS) and the standardized Vietnamese version of the IBS Quality of Life (IBS-QoL) questionnaire, respectively. Clinical characteristics, comorbidities, and overlap syndromes were also recorded. Results. Among the 123 patients enrolled (mean age 42.6 ± 14.5 years; 55.3% female), the median IBS-SSS score was 175 (interquartile range: 140–225), and the median IBS-QoL score was 72 (interquartile range: 54–85). The prevalence of overlap syndromes was relatively high, with functional dyspepsia accounting for 46.3% and gastroesophageal reflux disease for 8.9%. A moderate inverse correlation was observed between IBS-SSS and IBS-QoL scores (r = −0.494; p < 0.001). Notably, patients with severe IBS (IBS-SSS ≥ 300) had significantly higher rates of smoking (44.4% vs. 13.2%; p = 0.012) and diabetes (22.2% vs. 5.3%; p = 0.047) compared to the non-severe group. Conclusions. IBS-D imposes a substantial symptom burden and significantly reduces the quality of life in Vietnamese patients, particularly among those with severe disease. The high prevalence of overlap syndromes, along with contributing factors like smoking and diabetes, further increase the complexity and severity of the condition.