Prevalence and duration of gastrointestinal symptoms before diagnosis of Inflammatory Bowel Disease and predictors of timely specialist review: a population-based study

BACKGROUND AND AIMS

Lack of timely referral and significant waits for specialist review amongst individuals with unresolved gastrointestinal (GI) symptoms can result in delayed diagnosis of Inflammatory Bowel Disease (IBD).

AIMS

To determine the frequency and duration of GI symptoms and predictors of timely specialist review before the diagnosis of both Crohn's Disease (CD) and ulcerative colitis (UC).

METHODS

Case-control study of IBD matched 1:4 for age and sex to controls without IBD using the Clinical Practice Research Datalink from 1998-2016.

RESULTS

We identified 19,555 cases of IBD, and 78,114 controls. 1 in 4 cases of IBD reported gastrointestinal symptoms to their primary care physician more than 6 months before receiving a diagnosis. There is a significant excess prevalence of GI symptoms in each of the 10 years before IBD diagnosis. GI symptoms were reported by 9.6% and 10.4% at 5 years before CD and UC diagnosis respectively compared to 5.8% of controls. Amongst patients later diagnosed with IBD, <50% received specialist review within 18 months from presenting with chronic GI symptoms. Patients with a previous diagnosis of irritable bowel syndrome or depression were less likely to receive timely specialist review (IBS: HR=0.77, 95%CI 0.60-0.99, depression: HR=0.77, 95%CI 0.60-0.98).

CONCLUSIONS

There is an excess of GI symptoms 5 years before diagnosis of IBD compared to the background population which are likely attributable to undiagnosed disease. Previous diagnoses of IBS and depression are associated with delays in specialist review. Enhanced pathways are needed to accelerate specialist referral and timely IBD diagnosis.

Steroid dependency and trends in prescribing for inflammatory bowel disease - a 20-year national population-based study

BACKGROUND

It is unclear whether adherence to prescribing standards has been achieved in inflammatory bowel disease (IBD).

AIM

To determine how prescribing of 5-aminosalicylates (5-ASAs), steroids and thiopurines has changed in response to emerging evidence.

METHODS

We examined trends in oral and topical therapies in 23 509 incident IBD cases (6997 with Crohn's disease and 16 512 with ulcerative colitis) using a nationally representative sample between 1990 and 2010. We created five eras according to the year of diagnosis: era 1 (1990-1993), era 2 (1994-1997), era 3 (1998-2001), era 4 (2002-2005) and era 5 (2006-2010). We calculated the proportion of patients treated with prolonged 5-ASAs (>12 months) and steroid dependency, defined as prolonged steroids (>3 months) or recurrent (restarting within 3 months) steroid exposure. We calculated the cumulative probability of receiving each medication using survival analysis.

RESULTS

Half of the Crohn's disease patients were prescribed prolonged oral 5-ASAs during the study, although this decreased between era 3 and 5 from 61.8% to 56.4% (P = 0.002). Thiopurine use increased from 14.0% to 47.1% (P < 0.001) between era 1 and 5. This coincided with a decrease in steroid dependency from 36.5% to 26.8% (P < 0.001) between era 1 and 2 and era 4 and 5 respectively. In ulcerative colitis, 49% of patients were maintained on prolonged oral 5-ASAs. Despite increasing thiopurine use, repeated steroid exposure increased from 15.3% to 17.8% (P = 0.02) between era 1 and 2 and era 4 and 5 respectively.

CONCLUSIONS

Prescribing in clinical practice insufficiently mirrors the evidence base. Physicians should direct management towards reducing steroid dependency and optimising 5-ASA use in patients with IBD.

The impact of timing and duration of thiopurine treatment on colectomy in ulcerative colitis: a national population-based study of incident cases between 1989-2009

BACKGROUND

The role of thiopurines in altering the risk of colectomy in ulcerative colitis (UC) remains unclear.

AIMS

To examine predictors of colectomy in UC and determine the impact of thiopurines on the risk of colectomy.

METHODS

We constructed a population-based cohort of incident cases of UC in the United Kingdom between 1989 and 2009. We determined trends in thiopurine usage and colectomy for three defined cohorts: era 1 (1989-1995), era 2 (1996-2002), era 3 (2003-2009). We used Cox regression to determine predictors of colectomy and quantified the impact of duration and timing of thiopurine use on the risk of colectomy.

RESULTS

We identified 8673 incident cases of UC. 5-year colectomy rates increased from 4.2%, 5.1% to 6.9% (P = 0.001) for era 1, era 2 and era 3, respectively, despite increasing thiopurine use. This was not significant after adjustment for predictors of colectomy (P = 0.06). There was a higher risk of colectomy in men (HR 1.44, 95% CI: 1.19-1.73), those diagnosed at an early age (HR 1.35, 95% CI: 1.04-1.75; 16-24 vs. 25-64) and early steroid users (HR 1.94, 95% CI: 1.59-2.37). 5-ASA users were less likely to require a colectomy (HR 0.35, 95% CI: 0.28-0.44). Amongst thiopurine users, those treated for greater than 12 months had a 71% reduction in risk of colectomy (HR 0.29, 95% CI: 0.21-0.40). Early thiopurines offered no additional benefit.

CONCLUSIONS

Thiopurine exposure for greater than 12 months reduces the likelihood of colectomy by 71%. Young men and those requiring steroids within 3 months of diagnosis are at greatest risk of colectomy, and most likely to benefit from sustained thiopurine use.

Viruses causing diarrhoea in AIDS

Opportunistic viral enteritis is an important gastrointestinal manifestation of HIV related disease. Cytomegalovirus (CMV) is a well established aetiological agent of disease in the gastrointestinal tract in this group. CMV enteritis may affect any region of the bowel, most commonly the colon. Diagnosis and management of these infections may be difficult. The role of other viruses in so-called 'pathogen-negative' diarrhoea remains controversial. The clinical importance of HIV-specific enteropathy is probably limited. Several viruses including astrovirus, picobirnavirus, small round structured virus and rotavirus have been implicated HIV-related diarrhoea. In addition, adenovirus has been linked to persistent diarrhoea in patients with a characteristic adenovirus colitis. The spectrum of disease morbidity and mortality amongst HIV patients has altered dramatically since the wide spread use of highly active antiretroviral therapy (HAART). Opportunistic infections, including CMV infection of the gastrointestinal tract in patients with AIDS, have diminished greatly. AIDS patients with CMV are able successfully to discontinue anti-CMV treatment without disease reactivation and with a parallel reduction in CMV viraemia following the initiation of HAART.

Interferon gamma induces enterocyte resistance against infection by the intracellular pathogen Cryptosporidium parvum

BACKGROUND & AIMS

Interferon (IFN)-gamma plays an important role in the immunologic control of infection by the protozoan enteropathogen Cryptosporidium parvum. We tested the hypothesis that IFN-gamma may directly inhibit infection of enterocytes by this pathogen.

METHODS

HT-29, Caco-2, and H4 human enterocyte cell lines were grown in monolayers and incubated with IFN-gamma before exposure with C. parvum. IFN-gamma receptor expression in the cell lines was determined by Western blot analysis.

RESULTS

IFN-gamma inhibited C. parvum infection of both HT-29 and Caco-2 cells but not H4 cells. Response to IFN-gamma was related to the expression of the IFN-gamma receptor in the respective cell lines. The effect of IFN-gamma was partially reversed by inhibition of the JAK/STAT signaling pathway. IFN-gamma mediated its action by at least 2 mechanisms: (1) inhibition of parasite invasion and (2) by modification of intracellular Fe(2+) concentration. No role for tryptophan starvation or nitric oxide synthase activity was found. TNF-alpha and IL-1beta also had anti-C. parvum activity but had no synergistic effect with IFN-gamma.

CONCLUSIONS

IFN-gamma directly induces enterocyte resistance against C. parvum infection; this observation may have important consequences for our understanding of the mucosal immune response to invasive pathogens.

Enteric viruses in HIV-related diarrhoea

HIV-related diarrhoea is an important cause of morbidity and mortality in HIV infection. Cytomegalovirus is a well-established cause of diarrhoea, but the role of other enteric viruses is less clear and will be discussed here. The clinical manifestations, disease mechanisms, diagnostic techniques and current treatments for the management of these infections are reviewed.

Mannose-binding lectin is a component of innate mucosal defense against Cryptosporidium parvum in AIDS

BACKGROUND & AIMS

Nonimmune mechanisms of mucosal defense seem to be biologically important and might explain the observed variability in the course of enteric infection in immunodeficiency. Mannose-binding lectin (MBL) deficiency is associated with persistent diarrhea in children. We found that genetic determinants of MBL deficiency appear to predispose to cryptosporidiosis in patients with the acquired immunodeficiency syndrome (AIDS), and went on to study interactions of MBL and complement on Cryptosporidium parvum sporozoites.

METHODS

This study involved cross-sectional study of MBL genotype and enteric infection in 72 Zambian AIDS patients with diarrhea, immunofluorescence analysis of MBL and C4 binding to C. parvum, and immunoblotting for MBL and complement in small intestinal fluid.

RESULTS

Individuals homozygous for MBL structural gene mutations were at increased risk of cryptosporidiosis (odds ratio, 8.2; 95% confidence interval, 1. 5-42; P = 0.02). Lectin-mediated and concentration-dependent binding of purified MBL was detected on sporozoites but not oocysts, and MBL activated C4 on sporozoites. MBL, C3, C4, and albumin were detected in small intestinal fluid in half the patients tested, suggesting transudation of serum components into the enteropathic gut.

CONCLUSIONS

The increased risk of cryptosporidiosis in MBL deficiency appears to include patients with AIDS. It may operate through MBL-mediated complement activation on sporozoites.

Dilutional diarrhoea: under-diagnosed and over-investigated

We report two cases of factitious diarrhoea caused by stool dilution. In the first report stools from a patient with chronic diarrhoea were found to have been diluted with urine, and the diarrhoea further compounded by surreptitious laxative misuse. In the second report, after prolonged investigation of high output ileostomy, the patient's ileal effluent was found to have been diluted with water. We conclude that factitious diarrhoea, in particular dilutional diarrhoea, is over-investigated and underdiagnosed. Stool weights, complete input/output measurement, analysis of stool osmolality and electrolytes, and laxative screening are essential in the investigation of chronic watery diarrhoea.

Enteric viral infections as a cause of diarrhoea in the acquired immunodeficiency syndrome

BACKGROUND AND AIMS

The role of non-cytomegalovirus (CMV) enteric viral infection in causing diarrhoea in patients with human immunodeficiency virus (HIV) is poorly understood. We aimed to investigate the prevalence of these infections in acute and chronic diarrhoea.

METHODS

Stool specimens from 377 HIV-infected patients presenting with diarrhoea were studied prospectively for evidence of non-CMV enteric viral infection. Patients with diarrhoea underwent investigation for gastrointestinal pathogens, including electron microscopic examination of stool for enteric viruses. We collected data on patients in whom enteric virus was identified and examined the association of enteric virus infection with diarrhoeal symptomatology.

RESULTS

Eighty-nine (10.3%) stool specimens from 60 (15.9%) HIV+ individuals were positive for coronavirus (n = 13, 22%), rotavirus (n = 11, 18%), adenovirus (n = 30, 50%) and small round structured viruses (n = 5, 8%) or dual infection (n = 2, 3%). Thirty-four of 52 (65%) patients available for analysis had acute diarrhoea, and 18/52 (35%) had chronic diarrhoea. Twenty-three of 52 (44%) patients had a concurrent gut pathogen. After exclusion of concurrent pathogens enteric viral infections were found to be significantly associated with acute as opposed to chronic diarrhoea (P = 0.004). The presence of adenovirus colitis was significantly more likely to be associated with chronic diarrhoea (15/21 cases) than adenovirus isolated from stool alone (9/23 cases) (P = 0.03). There was a trend towards an association between adenovirus colitis and colonic cytomegalovirus infection (P = 0.06).

CONCLUSION

Enteric viral infection is strongly associated with acute diarrhoea in patients with HIV. Light microscopic examination of large bowel biopsies can identify adenovirus colitis which is significantly associated with chronic diarrhoea, and in addition may facilitate gastrointestinal co-infection with CMV.