A Refractory, Gas-Predominant Subgroup of Irritable Bowel Syndrome Markedly Improved With Relatively Long-Term Paroxetine Treatment: A Preliminary Study

Background The intestinal-gas symptoms of irritable bowel syndrome (IBS) are particularly bothersome and refractory. In our Japanese clinical practice, we often experience IBS patients with severe complaints of excess 'flatulence' or 'rumbling' as well as bloating, and have considerable difficulty in treating them. However, few studies have been reported on this subgroup of IBS for whom intestinal-gas symptom is the most bothersome <i>(gas-predominant IBS</i>). Aims The aim of this study was to characterize the features of refractory <i>gas-predominant IBS</i> and to find an effective treatment strategy. Methods One hundred and forty-six consecutive patients who fulfilled the Rome IV criteria for IBS were divided into subgroups according to the most distressing symptom. Among these subgroups, we focused on a <i>gas-predominant IBS</i> group. 'Flatulence' is defined as 'excess flatulence' or 'incontinence of flatulence'. Patients with <i>gas-predominant IBS</i> were treated with paroxetine, amitriptyline, or both. 'Remission-like improvement' was defined as achieving a severity rating of 30% or less for all IBS symptoms within 24 months, and no relapse occurred for at least six months. Results Of the 146 patients, 31 (21.2%) were classified ashaving <i>gas-predominant IBS.</i> All were refractory to conventional treatment. Ten did not meet the required treatment conditions (lack of treatment-related information (n=6) and deviation from the treatment protocol (n=4)) and were excluded, leaving the data of 21 patients available for study. Of the 21 studied patients, the most bothersome symptoms were 'flatulence' in 14 (66.7%), 'rumbling' in three (14.3%), both 'flatulence' and 'rumbling' in three (14.3%) and bloating in one (4.8%). Notably, 17 (81.0%) rated 'flatulence' and six (28.6%) rated 'rumbling' as one of the worst symptoms. Fifteen (71.4%) of the 21 patients exhibited very high anxiety scores for both state and trait anxiety, while a total of two (9.5%) were diagnosed with a psychiatric disorder, major depressive disorder. Eighteen (85.7%) of the 21 patients achieved 'remission-like improvement' with five to 23 months of treatment with paroxetine (n=14), amitriptyline (n=2), or both (n=2), and no relapse occurred for at least six months. Conclusions In Japan, there is a distinct refractory subgroup of IBS who complain of intestinal-gas symptoms such as 'flatulence' or 'rumbling' as their most distressing symptom. Further studies are needed on the prevalence and regional specificity of <i>gas-predominant IBS</i> in Japan and globally. Paroxetine treatment for a relatively long period may be effective in treating refractory <i>gas-predominant IBS</i>. However, this study was open-label and lacked a control group, and future investigations are needed to determine the most appropriate use of paroxetine for the treatment of <i>gas-predominant IBS.</i>