Characterization of Symptoms in Irritable Bowel Syndrome (IBS) - PDF

NIH Public Access Author Manuscript Neurogastroenterol Motil. Author manuscript; available in PMC 2015 January 01. Published in final edited form as: NIH-PA Author Manuscript Neurogastroen...

NIH Public Access Author Manuscript Neurogastroenterol Motil. Author manuscript; available in PMC 2015 January 01. Published in final edited form as: NIH-PA Author Manuscript Neurogastroenterol Motil. 2014 January ; 26(1):. doi:10.1111/nmo.12220. Characterization of Symptoms in Irritable Bowel Syndrome with Mixed Bowel Habit Pattern Andrew Su1, Wendy Shih2, Angela P. Presson2,3,4, and Lin Chang5 1Northwestern University, Feinberg School of Medicine, Chicago, IL 2Department of Biostatistics, UCLA, Los Angeles, California 3Department of Internal Medicine, University of Utah, Los Angeles, California 4Department of Pediatrics, University of Utah, Los Angeles, California 5Oppenheimer Family Center for Neurobiology of Stress, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California NIH-PA Author Manuscript Abstract Background—Irritable bowel syndrome (IBS) with mixed bowel habits (IBS-M) is a heterogeneous subtype with varying symptoms of constipation and diarrhea, and has not been well characterized. We aimed to characterize gastrointestinal (GI) and non-GI symptoms in IBS-M patients from a U.S. community, and to compare them with IBS with constipation (IBS-C) and diarrhea (IBS-D). Methods—Subjects answering community advertisements and meeting Rome III criteria for IBS completed symptom questionnaires. Key Results—Of the initial 289 IBS patients identified, one-third (n=51, 32.5%) who met Rome III criteria for IBS-M endorsed having either loose stools or hard stools due to medication. These patients had more severe symptoms and longer duration of flares compared to the rest of the IBS- M group (p = 0.014, p = 0.005). Excluding IBS-M patients with medication-related extremes in stool form who could not be reclassified by medical history, 247 IBS patients were assessed. IBS- M was the most common (44.1%), followed by IBS-C (27.9%), IBS-D (26.3%), and IBS-U (unsubtyped, 1.6%). IBS-M shared symptoms with both IBS-C and IBS-D (p-value range: diarrhea”, “diarrhea > constipation”, or “equal constipation & diarrhea”. The distribution of stool frequency was also further categorized into “abnormal BM frequencies” and “normal BM frequencies”. “Abnormal BM frequencies” were defined as having BMs more than 3 times a day, less than 3 times a week, or having both at least 25% of the time. Patients with “normal BM frequencies” did not report any of the above. Interactions between stool form, stool frequency, and most bothersome symptoms were also analyzed. Non-GI Symptom Questionnaires Validated questionnaires were administered to assess psychological and somatic symptoms and health-related quality of life (HRQOL). A seven-question subscale of the full Coping NIH-PA Author Manuscript Strategies Questionnaire (CSQ) was used to measure catastrophizing as a coping strategy. (17) Scores were averaged with higher scores indicating greater catastrophizing. The Hospital Anxiety and Depression Scale (HAD) is a widely used 14-item questionnaire for assessing current symptoms of anxiety and depression. (19) The Patient Health Questionnaire (PHQ-15) is a somatic symptom subscale of the full PHQ covering the most common outpatient physical complaints and most prevalent somatic symptoms in the DSM- IV somatization disorder. (20) A PHQ-12 questionnaire, excluding three questions on GI symptoms to measure extraintestinal somatic symptoms only, was used in this study. Higher scores indicate greater somatic symptom severity. The Visceral Sensitivity Index (VSI) is a validated 15-item questionnaire developed to assess GI symptom-specific anxiety. (21) Lower scores indicate greater symptom-specific anxiety. The 12-Item Short Form Health Survey (SF-12) is a validated short form of the original 36-Item Short-Form Health Survey (SF-36) used to measure HRQOL. (22, 23) Physical and Mental Component Summary Scores (PCS & MCS) were calculated with 0 being the lowest level of health. Statistical Analysis Group comparisons among bowel habits and across IBS-M medication status were evaluated using a Kruskal-Wallis, Chi-square, Fisher's exact test, or multinominal regression. NIH-PA Author Manuscript Irregularity of bowel habits, typical symptoms and most bothersome symptom differences among the bowel habits were examined using a multinomial regression while controlling for racial/ethnicity differences. In addition, differences in irregularity of bowel habits, typical symptoms and most bothersome symptom and differences among the IBS-M subgroups based on predominant stool frequency and form and between IBS-M “medication” and “non-medication” groups were evaluated using Chi-square test or Fisher's exact test. Abdominal pain severity, presence of dyspepsia, presence of heartburn, psychological symptoms, or bowel movement frequencies were compared among IBS-C, IBS-D, and IBS- M using a Kruskal-Wallis test. All statistical analyses were performed using SAS version 9.2 (SAS Institute, Cary, NC, USA) or R version 2.14.1 (http://cran.r-project.org/). A p- value less than 0.05 was considered to be significant for all comparisons. There was no adjustment for multiple testing because the sample size was relatively small and this was considered to be an exploratory study. Neurogastroenterol Motil. Author manuscript; available in PMC 2015 January 01.  Su et al. Page 5 Results Subject clinical characteristics NIH-PA Author Manuscript The demographic and clinical symptom data are shown in Tables 1 and 2, respectively. Figure 1 shows the study subject selection flowchart. Of the initial 289 subjects who met Rome III criteria for IBS, two were excluded because a subtype could not be determined due to incomplete answers. Almost one-half (47.7%) reported having seen a doctor in the past year for their abdominal symptoms. About one-third (51 patients, 32.5%) of the initial 157 IBS-M patients answered positively to having either loose/watery stools or hard stools only when taking laxatives or anti-diarrheal medications. Forty of these patients were excluded from the comparison of IBS subtypes analysis after not being able to definitively conclude a true IBS bowel habit subclassification from review of the medical histories. Of the remaining 11, three remained IBS-M after review of medical histories, seven were reclassified to IBS-C, and one to IBS-D. The final analysis included 247 Rome III positive IBS patients with IBS-M being the most common subtype (109 patients, 44.1%), followed by IBS-C (69 patients, 27.9%), IBS-D (65 patients, 26.3%), and IBS-U (4 patients, 1.6%). Mean age, prevalence of women, and education did not differ between bowel habit subtypes. The mean age overall was 35.8 ± 12.6 (range: 18-70 yr). Women comprised the majority of the group, about 76% of the subjects. Race/ethnicity across IBS bowel habit subtypes with more African-Americans comprising the IBS-C group and more Asians and less Caucasians NIH-PA Author Manuscript in the IBS-D group (p=0.036). IBS-M Medication Group Compared with the 106 IBS-M patients without extreme stool forms only from medications, the 51 patients in the IBS-M medication group had greater severity of GI symptoms in the past week (11.62 ± 4.26 vs. 10.14 ± 3.84, p=0.014) with longer periods of flares (3.76 ± 1.76+ 1.76vs. 3.02 ± 1.64, p=0.005). There was also a higher prevalence of dyspepsia (66.7% vs. 46.2%, p=0.018). Furthermore, a greater proportion of the medication group reported sensation of incomplete evacuation (100% vs. 87.7%, p=0.010), severity of bloating (12.9 ± 5.26 vs. 11.22 ± 4.99, p=0.022), and infrequent BMs (BM < 3×/wk) (48.8% vs. 36.8%, p=0.011). There were no differences in gender, age, race, or psychological symptoms. Comparison of IBS-M to IBS-C and IBS-D Prevalence of IBS Symptoms—As shown in Figure 2, there were significant differences among IBS bowel habit subtypes for each of the following symptoms: abnormal BM frequencies (3BMs/day), straining with defecation, incomplete NIH-PA Author Manuscript emptying after defecation, the need for manual evacuation after defecation, and difficulty relaxing or letting go to allow the stool to come out during defecation (p-value range: