G. Richard Locke

The epidemiology of irritable bowel syndrome in North America: A systematic review

OBJECTIVE:The aim of this study was to systematically review published literature about the prevalence, incidence, and natural history of irritable bowel syndrome (IBS) in North America.METHODS:A computer-assisted search of MEDLINE, EMBASE, and Current Contents/Science Edition databases was performed independently by two investigators. Study selection criteria included: 1) North American population-based sample of adults; 2) objective diagnostic criteria for IBS (i.e., Rome or Manning criteria); and 3) publication in full manuscript form in English. Eligible articles were reviewed in a duplicate and independent manner. Data extracted were converted into individual tables and presented in descriptive form.RESULTS:The prevalence of IBS in North America ranges from 3% to 20%, with most prevalence estimates ranging from 10% to 15%. The prevalences of diarrhea-predominant and constipation-predominant IBS are both approximately 5%. Published prevalence estimates by gender range from 2:1 female predominance to a ratio of 1:1. Constipation-predominant IBS is more common in female individuals. The prevalence of IBS varies minimally with age. No true population-based incidence studies or natural history studies were found. In one cohort surveyed on two occasions 1 yr apart, 9% of subjects who were free of IBS at baseline reported IBS at follow-up producing an onset rate of 67 per 1000 person-years. In all, 38% of patients meeting criteria for IBS did not meet IBS criteria at 1-yr follow-up.CONCLUSION:Approximately 30 million people in North America meet the diagnostic criteria for IBS. However, data about the natural history of IBS is quite sparse and renewed efforts should be focused at developing appropriately designed trials of the epidemiology of IBS.

Risk factors associated with symptoms of gastroesophageal reflux

BACKGROUND Although patients with gastroesophageal reflux are often instructed to change their lifestyle, population-based data on the risk factors for reflux in the United States are lacking. METHODS We performed a cross-sectional study in an age- and gender-stratified random sample of the population of Olmsted County, Minnesota. Residents aged 25 to 74 years were mailed a valid self-report questionnaire that measured reflux symptoms and potential risk factors. Logistic regression was used to estimate the odds ratios (OR) with 95% confidence intervals (CI) for reflux symptoms (heartburn or acid regurgitation) associated with potential risk factors. RESULTS Overall, 1,524 (72%) of 2,118 eligible subjects responded. A body mass index >30 kg/m2 (OR = 2.8; CI, 1.7 to 4.5), reporting an immediate family member with heartburn or disease of the esophagus or stomach (OR = 2.6; CI, 1.8 to 3.7), a past history of smoking (OR = 1.6; CI, 1.1 to 2.3), consuming more than seven drinks per week (OR = 1.9; Cl, 1.1 to 3.3), and a higher psychosomatic symptom checklist score (OR per 5 units = 1.4; CI, 1.3 to 1.6) were independently associated with frequent (at least weekly) reflux symptoms. CONCLUSION Obesity is a strong risk factor for gastroesophageal reflux, although the value of weight reduction remains to be proven. That family history was also a risk factor suggests that there may be a genetic component to the disorder.

Epidemiology of Eosinophilic Esophagitis Over Three Decades in Olmsted County, Minnesota

BACKGROUND & AIMS Data on secular trends and outcomes of eosinophilic esophagitis (EE) are scarce. We performed a population-based study to assess the epidemiology and outcomes of EE in Olmsted County, Minnesota, over the last 3 decades. METHODS All cases of EE diagnosed between 1976 and 2005 were identified using the Rochester Epidemiology Project resources. Esophageal biopsies with any evidence of esophagitis and/or eosinophilic infiltration were reviewed by a single pathologist. Clinical course (treatment, response, and recurrence) was defined using information collected from medical records and prospectively via a telephone questionnaire. Incidence rates per 100,000 person years were directly adjusted for age and sex to the US 2000 population structure. RESULTS A total of 78 patients with EE were identified. The incidence of EE increased significantly over the last 3 of the 5-year intervals (from 0.35 [95% confidence interval (CI)], 0-0.87] per 100,000 person-years during 1991-1995 to 9.45 [95% CI, 7.13-11.77] per 100,000 person-years during 2001-2005). The prevalence of EE was 55.0 (95% CI, 42.7-67.2) per 100,000 persons as of January 1, 2006, in Olmsted County, Minnesota. EE was diagnosed more frequently in late summer/fall. The clinical course of patients with EE was characterized by recurrent symptoms (observed in 41% of patients). CONCLUSIONS The prevalence and incidence of EE is higher than previously reported. The incidence of clinically diagnosed EE increased significantly over the last 3 decades, in parallel with endoscopy volume. Seasonal incidence was greatest in late summer and fall. EE also appears to be a recurrent relapsing disease in a substantial proportion of patients.

American Gastroenterological Association Technical Review on Constipation

Constipation is a very common symptom. Prompted by several advances since the last technical review 15 years ago,1 this update will identify a rational, efficacious, and ideally cost-effective approach to patients with constipation. Toward those objectives, the epidemiology, clinical assessment, diagnostic testing, and management of constipation will be discussed, primarily from the perspective of a practicing gastroenterologist. Constipation in children and secondary constipation (eg, due to spinal cord injury) in adults will not be specifically addressed. This review was prepared by updating the previous technical review with material sourced from recent reviews on chronic constipation,2–4 supplemented by selected and focused literature searches of peer-reviewed, published studies. Although recommendations are graded based on US Preventive Services Task Force (USPSTF) ratings, formal cost-effectiveness analyses have not been performed. Comparisons of diagnostic approaches, with precise estimates of specificity and sensitivities, also have not been published. Indeed, in some instances, individual diagnostic techniques have not even been standardized.

Psychosocial Factors are Linked to Functional Gastrointestinal Disorders: A Population Based Nested Case-Control Study

BACKGROUND:It is widely accepted based on volunteer studies that levels of psychological distress are similar in those with functional gastrointestinal (GI) disorders and health in the community, while increased psychological distress in outpatients is largely explained by health-care seeking.AIMS:To determine if psychological distress, life event stress, or social support is associated with functional GI disorders in a population-based study.METHODS:A nested case-control study was performed by first mailing a self-report bowel disease questionnaire to a random sample of Olmsted County, Minnesota, aged 20–50 yr. All persons who reported symptoms of nonulcer dyspepsia (NUD) or irritable bowel syndrome (IBS) (cases), or an absence of GI symptoms (controls), were invited to complete a series of validated questionnaires designed to measure psychological distress, life event stress, social support, current symptoms, and physician visits.RESULTS:103 subjects with functional GI disorders and 119 controls participated (85% of eligible). Functional GI disorders were more likely to be reported by those with higher scores on each of the nine SCL-90-R scales used to measure psychological distress (except phobic anxiety), and those with more negative and total life event stress. In a multiple logistic regression model (including age and gender), somatization, interpersonal sensitivity, and total life event stress were independently associated with functional GI disorders. Findings were similar when subjects with the IBS and NUD were analyzed separately compared to controls.CONCLUSIONS:Contrary to current dogma, psychosocial factors were significantly associated with functional GI disorders in this community sample. This suggests that these factors may be involved in the etiopathogenesis rather than just driving health-care utilization.

Obesity is Associated with Increased Risk of Gastrointestinal Symptoms: A Population-Based Study

OBJECTIVES:Perception of sensations arising from the gastrointestinal tract may be diminished in obese subjects and thus facilitate overeating. Alternatively, excess food intake may cause gastrointestinal (GI) symptoms in obese patients. We evaluated the relationship between body mass index (BMI) and specific GI symptoms in the community.METHODS:Residents of Olmsted County, MN were selected at random to receive by mail one of two validated questionnaires. The association of reported GI symptoms with BMI (kg/m2) was assessed using a logistic regression analysis adjusting for age, gender, psychosomatic symptom score, and alcohol and tobacco use.RESULTS:Response rate was 74% (1,963 of 2,660). The prevalence of obesity (BMI ≥ 30 kg/m2) was 23%. There was a positive relationship between BMI and frequent vomiting (p = 0.02), upper abdominal pain (p = 0.03), bloating (p = 0.002), and diarrhea (p = 0.01). The prevalence of frequent lower abdominal pain, nausea, and constipation was increased among obese (BMI ≥ 30 kg/m2) compared to normal weight participants, however, no significant association was found between BMI and these symptoms.CONCLUSIONS:In the community, increasing BMI is associated with increased upper GI symptoms, bloating, and diarrhea. Clarification of the cause-and-effect relationships and the mechanisms of these associations require further investigation.

A comparison of the Rome and Manning criteria for case identification in epidemiological investigations of irritable bowel syndrome

Abstract OBJECTIVE: The aim of this study was to estimate the prevalence of irritable bowel syndrome using different standard definitions (Rome and Manning criteria) and to determine the degree of agreement between these definitions. METHODS: A population-based, cross-sectional survey study was conducted by mailing a valid, reliable questionnaire to an age- and gender-stratified random sample of residents of Olmsted County, MN, aged 30–69 yr. The threshold for a positive diagnosis of irritable bowel was varied from two to four of the six Manning criteria and from two to three of the five defecation disorders in the Rome criteria. Unadjusted as well as age- and gender-adjusted prevalence rates were calculated for each of the five definitions of IBS. Percent agreement and κ statistics were calculated to assess agreement between the definitions. RESULTS: Questionnaires were returned by 643 of 892 eligible subjects (72% response rate). The age- and gender-adjusted prevalence of IBS varied from 20.4% using a threshold of two symptoms in the Manning criteria to 8.5% using a threshold of three defecation disorders in the Rome criteria. The percent agreement for each comparison of Manning and Rome definitions was always >90%. The κ values ranged from 0.55 to 0.78, with the best agreement occurring between a threshold of three symptoms of Manning and two defecation disorders in Rome. CONCLUSIONS: The prevalence of IBS varied substantially depending on the specific definition of IBS used. The range of prevalence estimates in Olmsted County was similar to other published figures when IBS definition was accounted for. These findings are useful in interpreting epidemiological and clinical studies of IBS.

The Incidence, Prevalence, and Outcomes of Patients With Gastroparesis in Olmsted County, Minnesota, From 1996 to 2006

BACKGROUND & AIMS The epidemiology of gastroparesis is unknown. We aimed to determine the incidence, prevalence, and outcome of gastroparesis in the community. METHODS Using the Rochester Epidemiology Project, a medical records linkage system in Olmsted County, Minnesota, we identified county residents with potential gastroparesis. The complete medical records were reviewed by a gastroenterologist. Three diagnostic definitions were used: (1) definite gastroparesis, delayed gastric emptying by standard scintigraphy and typical symptoms for more than 3 months; (2) probable gastroparesis, typical symptoms and food retention on endoscopy or upper gastrointestinal study; (3) possible gastroparesis, typical symptoms alone or delayed gastric emptying by scintigraphy without gastrointestinal symptoms. Poisson regression was used to assess the association of incidence rates with age, sex, and calendar period. RESULTS Among 3604 potential cases of gastroparesis, 83 met diagnostic criteria for definite gastroparesis, 127 definite plus probable gastroparesis, and 222 any of the 3 definitions of gastroparesis. The age-adjusted (to the 2000 US white population) incidence per 100,000 person-years of definite gastroparesis for the years 1996-2006 was 2.4 (95% confidence interval [CI], 1.2-3.8) for men and 9.8 (95% CI, 7.5-12.1) for women. The age-adjusted prevalence of definite gastroparesis per 100,000 persons on January 1, 2007, was 9.6 (95% CI, 1.8-17.4) for men and 37.8 (95% CI, 23.3-52.4) for women. Overall survival was significantly lower than the age- and sex-specific expected survival computed from the Minnesota white population (P<.05). CONCLUSIONS Gastroparesis is an uncommon condition in the community but is associated with a poor outcome.

Risk factors for irritable bowel syndrome: role of analgesics and food sensitivities.

OBJECTIVE:Symptoms of irritable bowel syndrome (IBS) are reported by 10% of the general population; however, evaluation of traditional risk factors has not provided any insight into the pathogenesis of this condition. The objective of this study was to identify additional risk factors for irritable bowel syndrome.METHODS:A valid self-report questionnaire that records the gastrointestinal (GI) symptoms required for a diagnosis of IBS, self-reported measures of potential risk factors, and a psychosomatic symptom checklist was mailed to an age- and gender-stratified random sample of Olmsted County, Minnesota residents aged 30–64 yr. A logistic regression model that adjusted for age, gender, and psychosomatic symptom score was used to identify factors significantly associated with IBS.RESULTS:A total of 643 (72%) of 892 eligible subjects returned the survey. IBS symptoms were reported by 12% of the respondents. IBS was significantly associated with use of analgesics (acetaminophen, aspirin, or nonaspirin nonsteroidal antiinflammatory drugs) for reasons other than IBS, reporting a food allergy or sensitivity, and ratings of somatic symptoms. No association was detected for age, gender, body mass index, smoking history, alcohol use, educational level, exposure to pets in the household, or water supply. Among subjects reporting the use of just one type of analgesic, IBS was associated with acetaminophen but not aspirin or nonaspirin nonsteroidal antiinflammatory drugs used alone. The odds of having IBS were higher among subjects reporting more reasons for taking analgesics and intolerance to a higher number of foods.CONCLUSIONS:IBS is significantly associated with analgesic use. However, this is confounded by other somatic pain complaints. IBS symptoms are associated with the reporting of many food allergies or sensitivities. The role of food-induced symptoms in IBS requires further investigation.

A community-based, controlled study of the epidemiology and pathophysiology of dyspepsia

BACKGROUND & AIMS Dyspepsia is common in clinical practice and in the community. The relationship of the symptoms to meals and the pathophysiology in community dyspeptic patients is unclear. The purpose of this study was to measure symptoms, demographic features, and gastric motor and sensory functions associated with dyspepsia in the community. METHODS A Modified Bowel Disease Questionnaire was mailed to a random sample of Olmsted County, MN, residents. Dyspeptic patients and healthy controls identified among community respondents completed further questionnaires, Helicobacter pylori serology, gastric emptying by scintigraphy, gastric accommodation by 99mTc-single-photon emission computed tomography imaging, and postprandial symptoms and satiation by a nutrient drink test. RESULTS A total of 34.1% of community respondents reported dyspepsia within the past year, frequent (at least 25% of the time in the past year) in 17.5%, and 18.4% reported meal-related dyspepsia. Dyspepsia was frequent and related to meals in 10.8% of respondents. Compared with nondyspeptic controls, community dyspepsia was associated with higher aggregate symptom scores and bloating after a fully satiating meal. Community dyspepsia also was associated with higher somatization scores (P = .001), reporting of other somatic symptoms (P = .07), and general severity score on the symptom checklist 90 (P = .01), but not with disordered motor or sensory function. Gastric volumes, gastric emptying, and maximum tolerated volumes were not significantly different between community controls and dyspeptic patients. CONCLUSIONS Meal-related dyspepsia is an important component of dyspepsia in the community. Community dyspeptic patients have higher symptom scores after a fully satiating meal, consistent with gastric hypersensitivity. This is associated with higher somatization scores rather than disorders of gastric emptying or volumes.