The Epidemiology of Microscopic Colitis in Olmsted County, Minnesota: Population-Based Study From 2011 to 2019.

BACKGROUND & AIMS: Epidemiologic studies from Europe and North America have reported an increasing incidence of microscopic colitis (MC) in the late 20th century, followed by a plateau. This population-based study assessed recent incidence trends and the overall prevalence of MC over the past decade. METHODS: Residents of Olmsted County, MN, diagnosed with collagenous colitis (CC) or lymphocytic colitis (LC) between January 1, 2011, and December 31, 2019 were identified using the Rochester Epidemiology Project. Clinical variables were abstracted by chart review. Incidence rates were age- and sex-adjusted to the 2010 US population. Associations between incidence and age, sex, and calendar periods were evaluated using Poisson regression analyses. RESULTS: A total of 268 incident cases of MC were identified with a median age at diagnosis of 64 years (range, 19-90 y); 207 (77%) were women. The age- and sex-adjusted incidence of MC was 25.8 (95% CI, 22.7-28.9) cases per 100,000 person-years. The incidence of LC was 15.8 (95% CI, 13.4-18.2) and CC was 9.9 (95% CI, 8.1-11.9) per 100,000 person-years. A higher MC incidence was associated with increasing age and female sex (P < .01). There was no significant trend in age- and sex-adjusted incidence rate over the study period (P = .92). On December 31, 2019, the prevalence of MC, LC, and CC (including cases diagnosed before 2011) was 246.2, 146.1, and 100.1 per 100,000 persons, respectively. CONCLUSIONS: The incidence of MC and its subtypes was stable between 2011 and 2019, but its prevalence was higher than in previous periods. The incidence of MC continues to be associated with increasing age and female sex.

Experience and Outcomes at a Specialized Clostridium difficile Clinical Practice.

OBJECTIVE: To report our experience with and outcomes among patients referred to a specialized Clostridium difficile clinical practice. PATIENTS AND METHODS: We retrospectively identified consecutive patients referred for Clostridium difficile infection (CDI) management from January 1, 2013, through May 30, 2015. Data were collected for demographic characteristics, CDI history, final diagnoses, and management. RESULTS: Overall, 211 patients (median age, 65 years; 66.4% women) were included. The most common indications for referral were recurrent CDI in 199 patients (94.3%), first CDI episode in 5 patients (2.4%), and chronic diarrhea in 7 patients (3.3%). After evaluation, the diagnoses were recurrent CDI in 127 patients (60.2%), resolved CDI in 36 patients (17.1%), first-episode CDI in 5 patients (2.4%), and non-CDI in 43 patients (20.4%). The most common non-CDI diagnoses were postinfection irritable bowel syndrome (PI-IBS) in 32 patients (15.2% overall), inflammatory bowel disease (n=3), small intestinal bacterial overgrowth (n=2), microscopic colitis (n=1), and asymptomatic C difficile colonization (n=2). Two patients had diabetic gastroparesis and food intolerances, and 1 had chronic constipation with overflow diarrhea. Of 127 patients with recurrent CDI, 30 (23.6%) received antibiotics; of these 30, 12 had antibiotic treatment failure and received fecal microbiota transplantation (FMT) for recurrent CDI. Among 97 patients (76.4%) who underwent FMT, 85 (87.6%) were cured after the first FMT, 5 were cured after the second FMT, and 7 were treated with antibiotics for FMT failure, with resolution of symptoms. CONCLUSION: A substantial proportion of patients referred for CDI subsequently received alternative diagnoses; PI-IBS was the most common. Patients being referred for recurrent CDI should be evaluated carefully for alternative diagnoses.

The epidemiology of microscopic colitis in Olmsted County from 2002 to 2010: a population-based study.

BACKGROUND & AIMS: The increasing incidence of microscopic colitis has been partly attributed to detection bias. We aimed to ascertain recent incidence trends and the overall prevalence of microscopic colitis in a population-based study. METHODS: Using data from the Rochester Epidemiology Project, we identified residents of Olmsted County, Minnesota, who were diagnosed with collagenous colitis or lymphocytic colitis from January 1, 2002, through December 31, 2010, based on biopsy results and the presence of diarrhea (N = 182; mean age at diagnosis, 65.8 years; 76.4% women). Poisson regression analyses were performed to evaluate associations between incidence and age, sex, and calendar period. RESULTS: The age- and sex-adjusted incidence of microscopic colitis was 21.0 cases per 100,000 person-years (95% confidence interval [CI], 18.0-24.1 cases per 100,000 person-years). The incidence of lymphocytic colitis was 12.0 per 100,000 person-years (95% CI, 9.6-14.3 per 100,000 person-years) and collagenous colitis was 9.1 per 100,000 person-years (95% CI, 7.0-11.1 per 100,000 person-years). The incidence of microscopic colitis and its subtypes remained stable over the study period (P = .63). Increasing age (P < .001) and female sex (P < .001) were associated with increasing incidence. On December 31, 2010, the prevalence of microscopic colitis was 219 cases per 100,000 persons (90.4 per 100,000 persons for collagenous colitis and 128.6 per 100,000 persons for lymphocytic colitis). CONCLUSION: The incidence of microscopic colitis in Olmsted County residents has stabilized and remains associated with female sex and increasing age.

Comparative outcomes of younger and older hospitalized patients with inflammatory bowel disease treated with corticosteroids.

BACKGROUND: Data on the differences in inpatient treatment approaches and outcomes between younger and older patients with inflammatory bowel disease (IBD) are limited. Therefore, we used a parallel cohort study design to compare outcomes between younger and older patients with IBD. METHODS: All anti-tumor necrosis factor (TNF)-naive patients aged 60 years and older hospitalized at our institution between 2003 and 2011 and treated with corticosteroids for an IBD flare were matched 1:1 to younger patients aged 18 to 50 years. Rates of corticosteroid response, colectomy, and initiation of anti-TNF therapy were compared. RESULTS: Sixty-five patients were identified in each cohort. Median ages were 70 years (range, 60-94) and 30 years (range, 18-50) for the older and younger groups, respectively. Twenty-three percent of older patients were refractory to corticosteroids compared with 38% of the younger cohort (odds ratio, 0.5; 95% confidence intervals, 0.2-1.1). Older corticosteroid-refractory patients had surgery (80% versus 72%) and were started on anti-TNF therapy (20% versus 12%; P = 0.71), at a similar frequency as younger patients. Older steroid-responsive patients were less likely to start an anti-TNF agent during the first year of follow-up than younger patients (7% versus 31%, P = 0.006), but there was no difference in 1-year colectomy rates (27% versus 28%, P = 0.63). CONCLUSIONS: Corticosteroid response was similar in older and younger patients hospitalized for IBD. Inpatient treatment for corticosteroid-refractory patients was similar between cohorts. Older corticosteroid-responsive patients were less likely to be treated with an anti-TNF than younger patients.

Clinical factors associated with development of severe-complicated Clostridium difficile infection.

BACKGROUND & AIMS: Clostridium difficile infection (CDI) can cause life-threatening complications. Severe-complicated CDI is characterized by hypotension, shock, sepsis, ileus, megacolon, and colon perforation. We created a model to identify clinical factors associated with severe-complicated CDI. METHODS: We analyzed data from 1446 inpatient cases of CDI (48.6% female; median age, 62.5 years; range, 0.1-103.7 years) at the Mayo Clinic from June 28, 2007, to June 25, 2010. Patients with severe-complicated CDI (n = 487) were identified as those who required admission to the intensive care unit or colectomy, or died, within 30 days of CDI diagnosis. Logistic regression models were used to identify variables that were independently associated with the occurrence of severe-complicated CDI in 2 cohorts. One cohort comprised all hospitalized patients; the other comprised a subset of these inpatients who were residents of Olmsted County, Minnesota to assess the association of comorbid conditions with the development of severe-complicated infection in a population-based cohort. The linear combinations of variables identified by using logistic regression models provided scores to predict the risk of developing severe-complicated CDI. RESULTS: In a multivariable model that included all inpatients, increasing age, leukocyte count >15 × 10(9)/L, increase in serum level of creatinine >1.5-fold from baseline, and use of proton pump inhibitors or narcotic medications were independently associated with severe-complicated CDI. In the secondary analysis, which included only patients from Olmsted County, comorbid conditions were not significantly associated with severe-complicated CDI. CONCLUSIONS: Older age, high numbers of leukocytes in blood samples, an increased serum level of creatinine, gastric acid suppression, and use of narcotic medications were independently associated with development of severe-complicated CDI in hospitalized patients. Early aggressive monitoring and intervention could improve outcomes.

Tacrolimus salvage in anti-tumor necrosis factor antibody treatment-refractory Crohn's disease.

BACKGROUND: Several small retrospective studies have reported encouraging response rates in patients with Crohn's disease (CD) treated with tacrolimus. METHODS: We conducted a retrospective study of the use of oral tacrolimus for severe CD refractory to anti-tumor necrosis factor agents. Response was defined as a clinician's assessment of improvement after at least 7 days of treatment of one or more of the following: bowel movement frequency, fistula output, rectal bleeding, abdominal pain, extraintestinal manifestations, or well-being. Remission required all of the following: <3 stools per day, no bleeding, abdominal pain or extraintestinal manifestations, and increased well-being. RESULTS: Twenty-four eligible patients were treated with tacrolimus for a median of 4 months. Approximately 37% were steroid dependent or steroid refractory. Response and steroid-free remission rates were 67% and 21%, respectively, and lasted for a median of 4 months. Approximately 42% of patients were able to stop steroids and 54% of patients ultimately required surgery within a median of 10 months after starting tacrolimus. Patients with mean tacrolimus trough levels of 10 to 15 ng/mL had the highest rates of response (86%) and remission (57%). Surgery seemed to be postponed in this group compared with others. An adverse event occurred in 75% of patients. Eight of these events (33%) required dose reduction and 6 (25%) led to treatment discontinuation. There were no irreversible side effects or deaths attributable to tacrolimus over a median follow-up of 56 months. CONCLUSIONS: Oral tacrolimus seems to be safe and effective in some patients with severe CD refractory to anti-tumor necrosis factor therapy, particularly at a mean trough level of 10 to 15 ng/mL.

The epidemiology of Clostridium difficile infection in children: a population-based study.

BACKGROUND: The incidence of Clostridium difficile infection (CDI) is increasing, even in populations previously thought to be at low risk, including children. Most incidence studies have included only hospitalized patients and are thus potentially influenced by referral or hospitalization biases. METHODS: We performed a population-based study of CDI in pediatric residents (aged 0-18 years) of Olmsted County, Minnesota, from 1991 through 2009 to assess the incidence, severity, treatment response, and outcomes of CDI. RESULTS: We identified 92 patients with CDI, with a median age of 2.3 years (range, 1 month-17.6 years). The majority of cases (75%) were community-acquired. The overall age- and sex-adjusted CDI incidence was 13.8 per 100 000 persons, which increased 12.5-fold, from 2.6 (1991-1997) to 32.6 per 100 000 (2004-2009), over the study period (P < .0001). The incidence of community-acquired CDI was 10.3 per 100 000 persons and increased 10.5-fold, from 2.2 (1991-1997) to 23.4 per 100 000 (2004-2009) (P < .0001). Severe, severe-complicated, and recurrent CDI occurred in 9%, 3%, and 20% of patients, respectively. The initial treatment in 82% of patients was metronidazole, and 18% experienced treatment failure. In contrast, the initial treatment in 8% of patients was vancomycin and none of them failed therapy. CONCLUSIONS: In this population-based cohort, CDI incidence in children increased significantly from 1991 through 2009. Given that the majority of cases were community-acquired, estimates of the incidence of CDI that include only hospitalized children may significantly underestimate the burden of disease in children.

Symptomatic overlap between microscopic colitis and irritable bowel syndrome: a prospective study.

BACKGROUND: Microscopic colitis and irritable bowel syndrome (IBS) are the common causes of watery diarrhea, abdominal discomfort, and other gastrointestinal symptoms. Previous retrospective data and post hoc analysis of information from a randomized controlled trial have suggested that there is considerable overlap between the symptoms seen in patients with microscopic colitis and the symptom-based criteria for IBS. We sought to study this overlap in a prospective cohort. METHODS: A random cohort of patients with biopsy-proven microscopic colitis seen at our institution were administered a symptom questionnaire. Based on their responses, the proportion of patients who met various definitions for IBS was determined. Clinical characteristics of those meeting IBS criteria were compared with those who did not. RESULTS: In the 120 patients who were included, 38% to 58% met the diagnostic criteria for IBS. These patients tended to be younger and more likely female than those who did not meet IBS criteria. CONCLUSIONS: Patients with microscopic colitis frequently meet the diagnostic criteria for IBS. Therefore, these criteria are not specific enough to exclude the presence of microscopic colitis. In patients with watery diarrhea, colonoscopy with mucosal biopsies should be performed if symptoms are not controlled by antidiarrheal medications.

Outcomes of patients with microscopic colitis treated with corticosteroids: a population-based study.

OBJECTIVES: To evaluate the outcomes of corticosteroid-treated microscopic colitis (MC) in a population-based cohort, and to compare these outcomes in patients treated with prednisone or budesonide. METHODS: A historical cohort study of Olmsted County, Minnesota residents diagnosed with collagenous or lymphocytic colitis (LC) between 1986 and 2010 was performed using the Rochester Epidemiology Project. RESULTS: Of 315 patients with MC, 80 (25.4%) were treated with corticosteroids. The median age at colitis diagnosis was 66.5 years (range: 16-95) and 78.7% were female. Forty patients (50%) had LC and 40 (50%) had collagenous colitis. Prednisone was used in 17 patients (21.2%) and budesonide in 63 (78.8%); 56 (75.6%) had complete response and 15 (20.3%) had partial response. Patients treated with budesonide had a higher rate of complete response than those treated with prednisone (82.5 vs. 52.9%; odds ratio, 4.18; 95% CI, 1.3-13.5). Six patients were lost to follow-up. The remaining 74 had a median follow-up of 4 years (range 0.2-14). Fifty patients out of the 71 who responded (70.4%) had a recurrence after corticosteroid discontinuation. Patients treated with budesonide were less likely to recur than those treated with prednisone (hazard ratio, 0.38; 95% CI, 0.18-0.85; P=0.02). After 397 person years of follow-up in the 73 patients with long-term data, 47 (64.4%) required maintenance with corticosteroids. CONCLUSION: Patients with MC often respond to corticosteroid therapy, but with a high relapse rate. Budesonide had a higher response rate and a lower risk of recurrence than prednisone.

Gastric acid suppression and outcomes in Clostridium difficile infection: a population-based study.

OBJECTIVE: To evaluate the association of gastric acid suppression medications, including proton pump inhibitors and histamine type 2 blockers, with outcomes in patients with Clostridium difficile infection (CDI) in a population-based cohort. PATIENTS AND METHODS: To understand the association between acid suppression and outcomes in patients with CDI, we conducted a population-based study in Olmsted County, Minnesota, from January 1, 1991, through December 31, 2005. We compared demographic data and outcomes, including severe, severe-complicated, and recurrent CDI and treatment failure, in a cohort of patients with CDI who were treated with acid suppression medications with these outcomes in a cohort with CDI that was not exposed to acid-suppressing agents. RESULTS: Of 385 patients with CDI, 36.4% were undergoing acid suppression (23.4% with proton pump inhibitors, 13.5% with histamine type 2 blockers, and 0.5% with both). On univariate analysis, patients taking acid suppression medications were significantly older (69 vs 56 years; P<.001) and more likely to have severe (34.2% vs 23.6%; P=.03) or severe-complicated (4.4% vs 2.6% CDI; P=.006) infection than patients not undergoing acid suppression. On multivariable analyses, after adjustment for age and comorbid conditions, acid suppression medication use was not associated with severe or severe-complicated CDI. In addition, no association between acid suppression and treatment failure or CDI recurrence was found. CONCLUSION: In this population-based study, after adjustment for age and comorbid conditions, patients with CDI who underwent acid suppression were not more likely to experience severe or severe-complicated CDI, treatment failure, or recurrent infection.

An evaluation of repeat stool testing for Clostridium difficile infection by polymerase chain reaction.

GOALS: To evaluate the yield of repeat stool polymerase chain reaction (PCR) testing in patients with suspected Clostridium difficile infection (CDI). BACKGROUND: CDI is a major challenge in health care due to its frequent occurrence and high associated costs. Enzyme immunoassay and PCR are commonly performed diagnostic tests for CDI. METHODS: Our microbiology laboratory database was queried from January 1, 2008 to June 30, 2010 for all patients who underwent PCR stool testing for suspected CDI. Data collected included age, sex, number of stool tests performed within a 14-day period after the first test, and location of patient (inpatient vs. outpatient). Analyses were performed using JMP version 9.0.1. RESULTS: PCR testing was performed in 15,515 patients. The median age was 58.3 years (range, 10 d to 104.3 y) and 46.2% of patients were women. Repeat testing was infrequent; 87.3% of patients had testing performed only once in a 14-day period. Increased age, male sex, and inpatient location were predictors of repeat testing. The median time between an initial test and the first repeat test was 5 days. After an initial negative test, the percentage of patients having a subsequent positive test was low (2.7% in 7 d and 3.2% in 14 d). The percentage of repeat tests that was positive within 7 days (2.9%) was lower than the percentage that was positive from day 8 to day 14 (4.8%, P=0.05). CONCLUSIONS: Repeat testing for C. difficile has a low yield, and patients with an initial negative test should not routinely be retested.

The epidemiology of community-acquired Clostridium difficile infection: a population-based study.

OBJECTIVES: Clostridium difficile infection (CDI) is a common hospital-acquired infection with increasing incidence, severity, recurrence, and associated morbidity and mortality. There are emerging data on the occurrence of CDI in nonhospitalized patients. However, there is a relative lack of community-based CDI studies, as most of the existing studies are hospital based, potentially influencing the results by referral or hospitalization bias by missing cases of community-acquired CDI. METHODS: To better understand the epidemiology of community-acquired C. difficile infection, a population-based study was conducted in Olmsted County, Minnesota, using the resources of the Rochester Epidemiology Project. Data regarding severity, treatment response, and outcomes were compared in community-acquired vs. hospital-acquired cohorts, and changes in these parameters, as well as in incidence, were assessed over the study period. RESULTS: Community-acquired CDI cases accounted for 41% of 385 definite CDI cases. The incidence of both community-acquired and hospital-acquired CDI increased significantly over the study period. Compared with those with hospital-acquired infection, patients with community-acquired infection were younger (median age 50 years compared with 72 years), more likely to be female (76% vs. 60%), had lower comorbidity scores, and were less likely to have severe infection (20% vs. 31%) or have been exposed to antibiotics (78% vs. 94%). There were no differences in the rates of complicated or recurrent infection in patients with community-acquired compared with hospital-acquired infection. CONCLUSIONS: In this population-based cohort, a significant proportion of cases of CDI occurred in the community. These patients were younger and had less severe infection than those with hospital-acquired infection. Thus, reports of CDI in hospitalized patients likely underestimate the burden of disease and overestimate severity.

Observer variability in the histologic diagnosis of microscopic colitis.

BACKGROUND: Microscopic colitis is diagnosed based on histologic criteria. There has been no investigation of the reproducibility of the histologic diagnosis of microscopic colitis. Our aim was to evaluate interobserver and intraobserver variation in this diagnosis. METHODS: Colonic biopsies from 90 subjects (20 lymphocytic colitis, 20 collagenous colitis, 20 inflammatory bowel disease, and 30 normal) were blindly and independently reviewed by 4 gastrointestinal pathologists. The biopsies were classified by each pathologist into 1 of 6 diagnostic categories: lymphocytic colitis, collagenous colitis, active chronic colitis, focal active colitis, normal, or other. The slides were then relabeled and blindly reinterpreted 3 months later. The degree of agreement was determined using kappa statistics (lambda). RESULTS: Interobserver agreement with the 6 diagnostic categories was 69% (kappa = 0.76, 95% CI 0.69, 0.83) and 70% (kappa = 0.71, 95% CI 0.61, 0.79) for the first and second observations, respectively. Interobserver agreement with final diagnostic categories of microscopic colitis versus nonmicroscopic colitis was 91% (kappa = 0.90, 95% CI 0.82, 0.96) and 88% (kappa = 0.83, 95% CI 0.73, 0.92), respectively. Mean intraobserver agreement with the 6 diagnostic categories was 83% (kappa = 0.77). Mean intraobserver agreement with the final diagnostic categories of microscopic colitis versus nonmicroscopic colitis was 95% (kappa = 0.89). CONCLUSIONS: Both interobserver and intraobserver agreement were good in distinguishing among the 6 diagnostic categories, and excellent in distinguishing between microscopic colitis and nonmicroscopic colitis diagnoses. The histologic criteria for microscopic colitis provide for consistent and reproducible interindividual and intraindividual diagnoses in the evaluation of colonic biopsies.

Symptomatic overlap between irritable bowel syndrome and microscopic colitis.

BACKGROUND: Microscopic colitis is diagnosed on the basis of histologic criteria, and irritable bowel syndrome (IBS) is diagnosed by symptom-based criteria. There has been little investigation into the symptomatic overlap between these conditions. Our aim was to assess the prevalence of symptoms of irritable bowel syndrome in a population-based cohort of patients with microscopic colitis. METHODS: The Rochester Epidemiology Project (REP), a medical records linkage system providing all health care data for the defined population of Olmsted County, Minnesota, was used to identify all county residents with a diagnosis of microscopic colitis between 1985 and 2001. The medical records of these individuals were reviewed to ascertain symptoms consistent with Rome, Rome II, and Manning criteria for irritable bowel syndrome. RESULTS: One hundred thirty-one cases of microscopic colitis were identified. Median age at diagnosis was 68 years (range, 24-95); 71% were women. Sixty-nine (53%) and 73 (56%) met Rome and Rome II criteria for irritable bowel syndrome, respectively. Fifty-four (41%) had three or more Manning criteria. Forty-three (33%) had previously been diagnosed with irritable bowel syndrome. CONCLUSIONS: In this population-based cohort of histologically confirmed microscopic colitis, approximately one-half met symptom-based criteria for the diagnosis of irritable bowel syndrome. The clinical symptom-based criteria for irritable bowel syndrome are not specific enough to rule out the diagnosis of microscopic colitis. Therefore, patients with suspected diarrhea-predominant irritable bowel syndrome should undergo biopsies of the colon to investigate for possible microscopic colitis if symptoms are not well controlled by antidiarrheal therapy.

The epidemiology of microscopic colitis: a population based study in Olmsted County, Minnesota.

OBJECTIVE: Although the epidemiology of microscopic colitis has been described in Europe, no such data exist from North America. We studied the incidence, prevalence and temporal trends of microscopic colitis in a geographically defined US population. DESIGN AND SETTING: In this population based cohort study, residents of Olmsted County, Minnesota, with a new diagnosis of microscopic colitis, and all who had colon biopsies for evaluation of diarrhoea, between 1 January 1985 and 31 December 2001 were identified. Biopsies were reviewed for confirmation (cases) and to identify missed cases (diarrhoea biopsies). MAIN OUTCOME MEASURES: Incidence rates, age and sex adjusted to the 2000 US white population. Poisson regression assessed the association of calendar period, age and sex with incidence. RESULTS: We identified 130 incident cases for an overall rate of 8.6 cases per 100,000 person-years. There was a significant secular trend, with incidence increasing from 1.1 per 100,000 early in the study to 19.6 per 100,000 by the end (p<0.001). Rates increased with age (p<0.001). By subtype, the incidence was 3.1 per 100,000 for collagenous colitis and 5.5 per 100,000 for lymphocytic colitis. Collagenous colitis was associated with female sex (p<0.001) but lymphocytic colitis was not. Prevalence (per 100,000 persons) on 31 December 2001 was 103.0 (39.3 for collagenous colitis and 63.7 for lymphocytic colitis). CONCLUSIONS: The incidence of microscopic colitis has increased significantly over time, and by the end of the study, the incidence and prevalence were significantly higher than reported previously. Microscopic colitis is associated with older age, and collagenous colitis is associated with female sex.

Microscopic colitis is not associated with cholecystectomy or appendectomy.

BACKGROUND: Microscopic colitis is a common cause of chronic watery diarrhea of unknown origin. Some patients develop diarrhea after cholecystectomy, and some patients with microscopic colitis have evidence of bile acid malabsorption. However, the association between cholecystectomy and microscopic colitis has not been studied. A protective effect of appendectomy on the development of ulcerative colitis also has been reported, but its relationship with microscopic colitis has not been studied. The aim of this study was to assess cholecystectomy and appendectomy as potential risk factors for the development of microscopic colitis in a nested case-control study. MATERIALS AND METHODS: Using the Rochester Epidemiology Project, we identified all Olmsted County (Minnesota) residents with an initial diagnosis of microscopic colitis between January 1, 1985, and December 31, 2001. Rates of antecedent cholecystectomy or appendectomy in patients with microscopic colitis were compared with age-, gender-, and calendar year-matched community controls through conditional logistic regression. RESULTS: Microscopic colitis was identified in 130 cases. Cholecystectomy preceded the diagnosis of microscopic colitis in 12 cases (9%) compared with 17 (13%) in the control group (odds ratio [OR] 0.7; 95% CI 0.3-1.5). Appendectomy preceded the diagnosis of microscopic colitis in 39 subjects (30%) compared with 28 (22%) in the control group (OR 1.6; 95% CI 0.9-2.7). Similar results were obtained when the analysis was restricted to microscopic colitis subtype (lymphocytic colitis or collagenous colitis). CONCLUSIONS: In this population-based nested case-control study, no significant association was seen between cholecystectomy or appendectomy and the development of microscopic colitis or its subtypes.