Interstitial nephritis in patients with inflammatory bowel disease treated with mesalamine

Kidney Diseases Associated With Inflammatory Bowel Disease: Impact of Chronic Histologic Damage, Treatments, and Outcomes

INTRODUCTION

Kidney disease is a well-known extraintestinal manifestation (EIM) associated with inflammatory bowel disease (IBD), with a variety of underlying etiologies. However, little is known about the overall outcomes and predictors.

METHODS

This is a retrospective, observational cohort study. Patients with IBD in whom a native kidney biopsy was performed at Mayo Clinic (Rochester, MN) between 1994 and 2022, were included. Demographic, clinical, and histologic characteristics of prognostic interest were collected. The main outcomes were kidney failure, disease remission, kidney function changes at last follow-up, and death.

RESULTS

From a total cohort of 318 patients, we selected a study group of 111 patients followed-up with at our institution (45 ulcerative colitis [UC] and 66 Crohn's disease [CD]), with a mean age of 48 ± 17 years (40% females). IgA nephropathy (IgAN), chronic interstitial nephritis (CIN), and acute interstitial nephritis (AIN) were the most common diagnoses (22%, 19%, 13%, respectively). Median estimated glomerular filtration rate (eGFR) at presentation was 30 ml/min per 1.73 m2 (interquartile range [IQR]: 17-54) and urinary protein-to-creatinine ratio [UPCR] 0.8 g/g (0.3-3.4), without differences between IBD types. During a median follow-up of 59 months (12-109), 29 patients (26%) reached kidney failure. By multivariable analysis, the main predictors of kidney failure were age (hazard ratio [HR]: 1.04; P = 0.002), baseline eGFR (HR: 0.94; P = 0.003) and histologic chronicity score (HR: 4.01; P < 0.001). Therapeutic management varied according to underlying etiology. Global survival (kidney failure + death) was significantly better in patients who achieved complete or partial remission, or stabilization or improvement of kidney function.

CONCLUSION

One-fourth of patients with IBD with kidney disease may reach kidney failure, and the main determinants of this outcome is age, baseline eGFR, and degree of chronicity in kidney biopsy.

5-ASA induced interstitial nephritis in patients with inflammatory bowel disease: a systematic review

Background

Acute interstitial nephritis (AIN) is an important cause of kidney injury accounting for up to 27% of unexplained renal impairment. In up to 70% of cases, drugs, including aminosalicylates, are reported as the underlying cause. Following two recent paediatric cases of suspected mesalazine induced AIN within our own department, we performed a systematic review of the literature to address the following question: In patients with inflammatory bowel disease (IBD), is interstitial nephritis associated with 5-aminosalicylate (5-ASA) treatment? Our primary objective was to identify the number of cases reported in the literature of biopsy-proven 5-ASA induced interstitial nephritis, in children and adults with IBD. We also aimed to identify which variables influence the onset, severity and recovery of 5-ASA interstitial nephritis.

Methods

Embase and PubMed databases were searched from inception to 07/10/20. Search terms had three main themes: “inflammatory bowel disease”, “interstitial nephritis” and “aminosalicylates”. Studies were included if they reported an outcome of AIN, confirmed on biopsy, suspected to be secondary to a 5-ASA drug in those with IBD. A narrative synthesis was performed.

Results

Forty-one case reports were identified. Mesalazine was the most frequently reported aminosalicylate associated with AIN (95%). The median duration of treatment before AIN was diagnosed was 2.3 years (Interquartile Range (IQR) 12–48 months). The median rise in creatinine was 3.3 times the baseline measurement (IQR 2.5–5.5). Aminosalicylate withdrawal and steroids were the most frequently used treatments. Despite treatment, 15% of patients developed end-stage renal failure.

Conclusions

AIN is a serious adverse drug reaction associated with aminosalicylates, with mesalazine accounting for most reports. The current guidance of annual monitoring of renal function may not be sufficient to identify cases early. Given the severity of AIN and reports in the literature that early treatment with steroids may be beneficial, we would recommend at least 6 monthly monitoring of renal function.

PROSPERO registration number CRD42020205387.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00687-y.

The Association of Mesalamine With Kidney Disease

The package inserts for products containing 5-aminosalicylic acid, or mesalamine, include the following language regarding the risk of adverse kidney effects: "renal impairment, including minimal change nephropathy, acute and chronic interstitial nephritis, and rarely renal failure, has been reported in patients given products such as mesalamine delayed-release tablets that contain mesalamine or are converted to mesalamine." In this article, we review the data regarding this nephrotoxicity and the recommendations regarding appropriate monitoring. Chronic interstitial nephritis is a rare occurrence in patients treated with these drugs for Crohn disease and ulcerative colitis. Patients often present with asymptomatic reductions in glomerular filtration rate, without accompanying pyuria, skin lesions, or eosinophilia, unlike cases of acute interstitial nephritis. Drug cessation is usually associated with improved kidney function. However, if left undetected, more prolonged exposure to the drug can lead to irreversible kidney failure and end-stage kidney disease. No convincing studies demonstrate efficacy of treatment with corticosteroids. Frequent monitoring of serum creatinine, especially in the first years after initiation of therapy, is recommended.

[Renal and Urinary Manifestations of Inflammatory Bowel Disease]

The incidence of inflammatory bowel disease (IBD) is increasing rapidly and extra-intestinal manifestations in IBD are also increasing. The prevalence of renal and urinary involvement in IBD ranges from 4-23%. Nephrolithiasis is the most common urinary complication in IBD patients. Parenchymal renal disease is rare but has been well documented and presents most commonly as glomerulonephritis or tubulointerstitial nephritis. The overall morbidity of IBD-related renal manifestations is significant. Therefore, a high index of clinical suspicion and optimal monitoring of the renal function are needed for the early diagnosis and prevention of IBD-related renal manifestations and complications.

A Concise History of Thiopurines for Inflammatory Bowel Disease: From Anecdotal Reporting to Treat-to-Target Algorithms

BACKGROUND

The need for immune suppressive strategies in the control of chronic inflammatory bowel diseases originated in the 1960s following the perception of a relative inefficacy of salazopyrin and its derivatives. In some 50 years upon an anecdotal claim, the indication for thiopurines in the management of inflammatory bowel diseases has come of age.

OBJECTIVE

The aim of this minireview is to give an overview, after the historical premises, of the current use of thiopurines in the context of inflammatory bowel diseases.

METHOD

Through MEDLINE searches, we reviewed the literature of the last two decades.

RESULTS

For Crohn's disease, the 1980 trial of 6-mercaptopurine for steroid sparing and fistula closure proved pivotal. The analysis of withdrawal experiments and of numerous open trials has established the efficacy of thiopurines for ulcerative colitis. In this indication, cutting-edge data are now showing that because targeting dysplasia, thiopurines can induce mucosal/histological healing, thus abolishing or delaying the need for pre-emptive (tumor prophylactic) colectomy.

CONCLUSION

In UC thiopurines may be recognized to effect a treat-to-target strategy, joining the modern algorithms of rheumatologic disorders.

Renal Manifestations of Inflammatory Bowel Disease

Renal and urinary involvement has been reported to occur in 4% to 23% of inflammatory bowel disease (IBD) patients. Parenchymal renal disease is rare and most commonly affects glomerular and tubulointerstitial compartments. The most common findings on renal biopsy of IBD patients are IgA nephropathy and tubulointerstitial nephritis. Overall morbidity of IBD-related renal manifestations is significant, and there is often only a short window of injury reversibility. This, along with subtle clinical presentation, requires a high index of suspicion and routine monitoring of renal function. There are no established guidelines for the optimal screening and monitoring of renal function in IBD patients.

Mass-forming renal Crohn's disease: a case report with multimodality imaging

The most common extraintestinal manifestations of Crohn’s disease involve the eyes, skin, hepatobiliary tract, and the musculoskeletal and respiratory systems. Mass-forming granulomatous inflammation in extraintestinal organs is extremely rare and there are only a few reports of patients with Crohn’s disease presenting with inflammatory pseudotumours of the liver, pancreas and kidneys. We present a case of a mass-forming renal granulomatous inflammation in an adult female with Crohn’s disease. The clinical, pathological and imaging features of this case illustrate that renal inflammatory pseudotumour is a rare but important differential diagnosis of a renal mass in patients with Crohn’s disease and that radiologists should be aware of its existence when considering other more common pathologies, such as focal pyelonephritis and renal tumours. Renal inflammatory pseudotumour may have relatively non-specific imaging features and a biopsy may be required to make the diagnosis.

Chronic Kidney Disease in Aged Cats: Clinical Features, Morphology, and Proposed Pathogeneses

Chronic kidney disease (CKD) is the most common metabolic disease of domesticated cats, with most affected cats being geriatric (>12 years of age). The prevalence of CKD in cats exceeds that observed in dogs, and the frequency of the diagnosis of CKD in cats has increased in recent decades. Typical histologic features include interstitial inflammation, tubular atrophy, and fibrosis with secondary glomerulosclerosis. In contrast to people and dogs, primary glomerulopathies with marked proteinuria are remarkably rare findings in cats. Although a variety of primary renal diseases have been implicated, the disease is idiopathic in most cats. Tubulointerstitial changes, including fibrosis, are present in the early stages of feline CKD and become more severe in advanced disease. A variety of factors-including aging, ischemia, comorbid conditions, phosphorus overload, and routine vaccinations-have been implicated as factors that could contribute to the initiation of this disease in affected cats. Factors that are related to progression of established CKD, which occurs in some but not all cats, include dietary phosphorus intake, magnitude of proteinuria, and anemia. Renal fibrosis, a common histologic feature of aged feline kidneys, interferes with the normal relationship between peritubular capillaries and renal tubules. Experimentally, renal ischemia results in morphologic changes similar to those observed in spontaneous CKD. Renal hypoxia, perhaps episodic, may play a role in the initiation and progression of this disease.

Renal Involvement in Inflammatory Bowel Diseases

The prevalence of extraintestinal manifestations in inflammatory bowel diseases varies from 6% to 46%. The aetiology of extraintestinal manifestations remains unclear. There are theories based on an immunological response influenced by genetic factors. Extraintestinal manifestations can involve almost every organ system. They may originate from the same pathophysiological mechanism of intestinal disease, or as secondary complications of inflammatory bowel diseases, or autoimmune diseases susceptibility. The most frequently involved organs are the joints, skin, eyes, liver and biliary tract. Renal involvement has been considered as an extraintestinal manifestation and has been described in both Crohn's disease and ulcerative colitis. The most frequent renal involvements in patients with inflammatory bowel disease are nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis and amyloidosis. The aim of this review is to evaluate and report the most important data in the literature on renal involvement in patients with inflammatory bowel disease. Bibliographical searches were performed of the MEDLINE electronic database from January 1998 to January 2015 with the following key words (all fields): (inflammatory bowel disease OR Crohn's disease OR ulcerative colitis) AND (kidney OR renal OR nephrotoxicity OR renal function OR kidney disease OR renal disease OR glomerulonephritis OR interstitial nephritis OR amyloidosis OR kidney failure OR renal failure) AND (5-aminosalicylic acid OR aminosalicylate OR mesalazine OR TNF-α inhibitors OR cyclosporine OR azathioprine OR drugs OR pediatric).

The histopathologic spectrum of kidney biopsies in patients with inflammatory bowel disease

BACKGROUND AND OBJECTIVES

Kidney disease as a complication of inflammatory bowel disease (IBD), including Crohn disease (CD) and ulcerative colitis (UC), has been the subject of case reports. However, no cases series examining IBD and kidney disease has been published to date. This study aimed to evaluate a large series of kidney biopsy specimens from patients with IBD to better define the spectrum and relative frequencies of IBD-associated kidney pathology.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective review of native kidney biopsy specimens obtained from March 2001 to June 2012 identified 83 patients with IBD. Standard processing of all biopsy specimens included light microscopy, immunofluorescence, and electron microscopy.

RESULTS

There were 45 cases of CD and 38 cases of UC represented. The most common indication for kidney biopsy was acute or chronic kidney failure (63% [52 of 83]) and nephrotic-range proteinuria (16% [13 of 83]). IgA nephropathy was the most common diagnosis (24% [20 of 83]), followed by interstitial nephritis (19% [16 of 83]), arterionephrosclerosis (12% [10 of 83]), acute tubular injury (8% [7 of 83]), proliferative GN (7% [6 of 83]), and minimal-change disease (5% [4 of 83]). When compared, the frequency of IgA nephropathy in IBD was significantly higher than in all other native renal biopsy specimens from the same time period (24% [20 of 83] versus 8% [2734 of 33,630]; P<0.001). Of the 16 cases of interstitial nephritis, 9 (56%) had current or recent past exposure to aminosalicylates, including all cases of granulomatous interstitial nephritis.

CONCLUSIONS

IBD is associated with a spectrum of kidney diseases most commonly affecting the glomerular and tubulointerstitial compartments. IgA nephropathy is the most frequent kidney biopsy diagnosis in IBD and has a significantly higher diagnostic prevalence compared with all non-IBD kidney biopsy specimens. This may reflect a common pathogenic mechanism. Although many cases of tubulointerstitial nephritis are related to aminosalicylate exposure, the possibility of a direct relationship with IBD cannot be ruled out.

Granulomatous Interstitial Nephritis as a Manifestation of Crohn Disease

Granulomatous interstitial nephritis is a rare extraintestinal manifestation of Crohn disease that has been described previously in 4 patients. We report a 23-year-old man with a history of Crohn disease since age 6 years who was admitted to the hospital for weight loss, fever, and bloody diarrhea in the midst of a recent flare up during the past 2 months. Investigations revealed anemia, high erythrocyte sedimentation rate, high C-reactive protein level, and an elevated serum creatinine level. Histopathologic examination of tissue specimens obtained at renal biopsy demonstrated granulomatous interstitial nephritis. Crohn disease needs to be in the differential diagnosis of granulomatous interstitial nephritis and can be a manifestation of drug allergy or the Crohn disease itself.

Frequency and risk factors of renal insufficiency in inflammatory bowel disease inpatients

BACKGROUND

Renal involvement in patients with inflammatory bowel disease (IBD) has been well documented. However, there was a paucity of data on the frequency of renal insufficiency and its risk factors in this patient population. The aim of the study was to determine the frequency and factors associated with renal insufficiency within IBD inpatients.

METHODS

This case-control study was conducted on both Crohn's disease and ulcerative colitis inpatients in our tertiary care center from 2009 to 2010. Patients were identified as having renal insufficiency by the criterion of glomerular filtration rate < 60 mL/min/1.73 m. The glomerular filtration rate was further assessed against normal reference ranges. Risk factors for renal insufficiency were evaluated by univariable and multivariable analyses.

RESULTS

A total of 251 eligible patients were included. The frequency of renal insufficiency was 15.9% (95% confidence interval: 11.4-20.5), with 40 patients having a glomerular filtration rate <60 mL/min/1.73 m. Univariable analysis demonstrated several possible risk factors, including older age at admission (42.0 ± 16.2 years versus 57.6 ± 13.3 years, P < 0.001), and a longer median duration of IBD (9.0 years [interquartile range: 3.5-20.0] versus 25.0 years [interquartile range: 15.0-36.0], P < 0.001). The multivariable logistic analysis demonstrated that for every 5-year increase in age at the time of admission, the likelihood of having renal insufficiency increased by 30%.

CONCLUSION

Acute or chronic renal sufficiency in IBD inpatients was common, especially in elderly. Acute renal insufficiency can be medically reversed if properly treated. We recommend that renal function be closely monitored in IBD inpatients.

Renal involvement in Crohn's disease: granulomatous inflammation in the form of mass lesion

Extraintestinal manifestations of Crohn's disease (CD) are varied and concentrated mainly to the skin and eye. Urinary tract or renal involvement is extremely rare. Herein we report on a case of renal lesion of a 50-year-old woman with a 15-year history of CD. Abdominal computed tomography scan of the patient identified heterogeneous multinodular mass lesions in the left kidney. Histology proved classic granulomatous inflammatory nodules with multinucleated giant cells, eosinophils, plasma cells, epithelioid cells, and spindle-shaped myofibroblasts in the areas, where the computed tomography scan indicated. After the extensive PubMed search in the literature, this is the first macroscopically documented and histologically proved, mass-like renal involvement in CD. From now on, differential diagnostics of renal mass lesions in CD should include the tumor-like, Crohn's-type granulomatous inflammation as direct kidney manifestation of the disease.

Renal manifestations and complications of inflammatory bowel disease

Renal manifestations and complications are not rare in patients with inflammatory bowel disease (IBD) and may present as nephrolithiasis, amyloidosis, tubulointerstitial nephritis, and glomerulonephritis. Symptoms of renal impairment are not always specific and since the underlying bowel disease is preponderant, renal function deterioration may be underestimated. Additionally, medical treatment of patients with IBD such as aminosalicylates, cyclosporine, and tumor necrosis factor-α inhibitors can cause renal complications, although direct correlation to bowel disease is not always clear. The well-documented renal manifestations and complications of IBD, as well as the possible renal side effects of new drugs, emphasize the need for periodic evaluation of renal function. New markers of renal function may facilitate early diagnosis and unravel the complex mechanisms responsible for kidney damage. The purpose of this review is to summarize the renal manifestations and complications as well as the markers of renal function utilized in IBD, attempting to shed more light on the pathophysiology of renal damage in IBD.

Effect of 5-aminosalicylates on renal function in patients with inflammatory bowel disease: 4-year follow-up study

OBJECTIVE

Nephrotoxicity has been described in some patients with inflammatory bowel disease (IBD) treated with 5-aminosalicylates (5-ASA). Our aim was to conduct a retrospective study of IBD patients, both with and without 5-ASA treatment, who underwent regular evaluation of renal function over a 4-year period.

METHODS

Serum creatinine was measured before the start of 5-ASA therapy, and thereafter yearly up to 4 years. Creatinine clearance (Cl(Cr)) was estimated from serum creatinine (Cockroft and Gault formula). The influence of 5-ASA treatment on renal function was assessed by univariate and multivariate analysis.

RESULTS

A total of 150 IBD patients (ulcerative colitis in 45%, Crohn's disease in 55%) were included. Sixty-two patients were receiving 5-ASAs (95% coated mesalazine, mean dose 1.9 +/- 0.8 g/day). Both serum creatinine levels and ClCr were similar in patients with and without 5-ASA treatment, and remained stable throughout the 4-year follow-up in patients taking 5-ASAs. In the multivariate analysis, 5-ASA treatment (or its dose) was not correlated with serum creatinine levels or Cl(Cr). No interstitial nephritis was reported during follow-up.

CONCLUSION

5-ASA-related renal disease was not found in our series, suggesting that the occurrence of renal impairment in IBD patients receiving these drugs is exceptional. Our results do not support the recommendation of serum creatinine monitoring in patients receiving 5-ASA treatment.

[Severe tubulo-interstitial nephritis secondary to 5-ASA]

We report a new case of chronic interstitial nephritis in a patient with ulcerative colitis diagnosed in 2002 who was originally treated with 5-ASA. Three years later deterioration of renal function was apparent with an increase in serum creatinine, which was normal before treatment. Withdrawal of 5-ASA led to partial improvement of renal function. In patients with a delayed diagnosis of kidney damage, recovery of renal function is incomplete and, in some cases, the patient even requires some form of renal replacement therapy. We stress the importance of monitoring renal function in patients diagnosed with inflammatory bowel disease treated with this drug.

Tubulointerstitial nephritis as an extraintestinal manifestation of Crohn's disease

BACKGROUND

A 12-year-old boy presented to hospital with a 6-month history of crampy pre-defecation abdominal pain, non-bloody diarrhea, anorexia and weight loss. Investigations revealed hypochromic microcytic anemia, a low serum iron level, a low serum ferritin level and an elevated serum creatinine level. Histopathological examination of tissue specimens obtained at esophagogastroduodenoscopy and colonoscopy revealed features of Crohn's disease, and a renal biopsy demonstrated tubulointerstitial nephritis. A second case of tubulointerstitial nephritis in a patient with Crohn's disease, is also presented.

INVESTIGATIONS

Physical examination, laboratory tests including full blood count, electrolytes, renal function, serum albumin, urinalysis and 24 h urinary protein, esophagogastroduodenoscopy, colonoscopy, abdominal ultrasonography, dimercaptosuccinic acid scan, renal diethylene triamine pentaacetic acid clearance study and renal biopsy.

DIAGNOSIS

Tubulointerstitial nephritis secondary to Crohn's disease.

MANAGEMENT

Prednisone therapy (60 mg/day) for 1 month followed by a tapering schedule over 3 months.

Acute tubular injury associated with mesalazine therapy in an adolescent girl with inflammatory bowel disease

Mesalazine is a first-line drug in pediatric inflammatory bowel disease, and is effective as primary treatment and maintenance therapy. It's usually well tolerated, but various side effects have been described. A 15-year-old female with ulcerative colitis developed polyuria, polydipsia, vomiting, and fatigue. She was receiving mesalazine (500 mg, thrice daily, p.o.) and prednisolone for 4 months. She was detected as acute tubular injury as she had dehydration, acidosis, hypostenuria, hematuria, proteinuria, low levels of potassium, uric acid and bicarbonate. These findings were attributed to interstitial nephritis as a side effect of mesalazine, however as renal biopsy was disapproved by the parents, it was not confirmed. After discontinuation of mesalazine her renal tubular functions improved. Potassium and phosphorus supplements were stopped after 7 months, although she had to continue bicarbonate supplementation. We conclude that regular renal screening is important in patients receiving 5-ASA therapy to prevent rare but serious complications, such as interstitial nephritis sometimes leading to chronic renal failure.

5-Aminosalicylates and renal function in inflammatory bowel disease: a systematic review

Nephrotoxicity has been described in some patients with inflammatory bowel disease (IBD) treated with 5-aminosalicylic acid (5-ASA). Studies with 5-ASA treatment in which serum creatinine or creatinine clearance was measured regularly show that nephrotoxicity is exceptional (mean rate of only 0.26% per patient-year). There have been several case reports, including 46 patients, of renal disease associated with 5-ASA treatment in patients with IBD. 5-ASA treatment-related nephrotoxicity is reported most often within the first 12 months, but also delayed presentation after several years has been shown. The absence of a clear relationship between 5-ASA dose and the risk of nephrotoxicity suggests that this complication is idiosyncratic rather than dose-related. Most of the patients with renal disease associated with 5-ASA treatment suffered interstitial nephritis, with symptoms and signs being nonspecific, which may delay detection for many months. The nephrotoxicity potential of mesalazine and sulfasalazine seems to be similar. The risk with different oral preparations of 5-ASA is probably too small to influence the choice of agent. Mesalazine should be withdrawn when renal impairment manifests in a patient with IBD; if this does not result in a fall in serum creatinine, then renal biopsy should be considered. A trial of high-dose steroid may be recommended in patients whose renal function does not respond to drug withdrawal. The optimal monitoring schedule of serum creatinine in patients receiving 5-ASA treatment remains to be established, as there is no evidence to date that either the test, or the frequency of testing, improves patient outcomes.

5-aminosalicylic acid is an attractive candidate agent for chemoprevention of colon cancer in patients with inflammatory bowel disease

Inflammatory bowel disease (IBD) is classically subdivided into ulcerative colitis (UC) and Crohn’s disease (CD). Patients with IBD have increased risk for colorectal cancer. Because the pathogenesis of colorectal carcinoma has not been entirely defined yet and there is no ideal treatment for colon cancer, cancer prevention has become increasingly important in patients with IBD. The two adopted methods to prevent the development of colon cancer in clinical practice include the prophylactic colectomy and colonoscopic surveillance. But patients and physicians seldom accept colectomy as a routine preventive method and most patients do not undergo appropriate colonoscopic surveillance. Chemoprevention refers to the use of natural or synthetic chemical agents to reverse, suppress, or to delay the process of carcinogenesis. Chemoprevention is a particularly useful method in the management of patients at high risk for the development of specific cancers based on inborn genetic susceptibility, the presence of cancer-associated disease, or other known risk factors. Prevention of colorectal cancer by administration of chemopreventive agents is one of the most promising options for IBD patients who are at increased risks of the disease. The chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against intestinal tumors has been well established. But with reports that NSAIDs aggravated the symptoms of colitis, their sustained use for the purpose of cancer chemoprevention has been relatively contraindicated in IBD patients. Another hopeful candidate chemoprevention drug for IBD patients is 5-aminosalicylic acid (5-ASA), which is well tolerated by most patients and has limited systemic adverse effects, and no gastrointestinal toxicity. 5-ASA lacks the well-known side effects of long-term NSAIDs use. Retrospective correlative studies have suggested that the long-term use of 5-ASA in IBD patients may significantly reduce the risk of development of colorectal cancer. According to the literature, this agent might well satisfy clinical expectations with respect to a safe and effective chemopreventive agent.

Mesalamine delivery systems: do they really make much difference?

Sulfasalazine's role as the first-line of therapy in patients with inflammatory bowel disease has led to the development of other "designer" aminosalicylates, which eliminate the sulfa-moiety, and attempt to target the topically active mesalamine to the inflamed bowel. Olsalazine sodium and balsalazide disodium utilize the same azo-bond structure as sulfasalazine, requiring release of active mesalamine by colonic bacteria, and thus targeting these agents to the colon. Other mesalamine delivery systems use pH-dependant- or moisture-release to liberate the active mesalamine in both the large and small bowel. Direct application of mesalamine via enema or suppository is also effective in patients with distal colitis. The pharmacology and thus the undesirable drug absorption rates differ between drugs, although the clinical importance of these characteristics is debatable. Differences in release-systems, the impact of the fed and fasting state, and unique patient intolerances to individual agents demand an understanding of each of these products, and their application to patient therapy.

Osteoporosis and other complications of inflammatory bowel disease

Osteoporosis has received increasing attention as a potential complication of inflammatory bowel disease (IBD). The first population-based data on incidence of fractures in an IBD population were published this past year. The incidence of fractures was one per 100 patient years. Compared with the general population, the fracture rate was increased; however, the relative risk was 1.4 and, therefore, not as high as might be expected from the myriad of studies reporting high rates of osteopenia measured by dual energy x-ray absorptiometry (DXA). Another area receiving increasing attention is that of the enhanced risk of venous thrombosis in patients with IBD. The first population-based incidence rates of venous thrombosis in IBD were also published this past year and showed that IBD patients are affected by venous thrombosis at a rate of approximately one per 200 patient years. The relative risk for venous thrombosis compared with the general population was 3.5. Several studies have reported on associated risk markers or genetic clotting abnormalities, but no clear paradigm has emerged to account for those patients who will suffer a clot. Finally, the first North American population-based study was published, quantifying the prevalence rates of extraintestinal manifestations in patients with IBD for at least 10 years. Some gender- and disease-specific findings emerged. This study found that iritis and uveitis were more common in female patients with ulcerative colitis (3.2%), primary sclerosing cholangitis (PSC) was most common in male patients with ulcerative colitis (3%), ankylosing spondylitis was most common in male patients with Crohn disease (2.7%), and erythema nodosum was most likely to occur in female patients with Crohn disease (1.9%).