A cost-effectiveness analysis of alternative disease management strategies in patients with Crohn's disease treated with azathioprine or 6-mercaptopurine

BACKGROUND: Azathioprine (AZA) is effective for the maintenance of a steroid free remission in Crohn's disease (CD). Thiopurine methyltransferase (TPMT) is important for the metabolism of AZA and influences the production of active AZA metabolites. AZA dose selection based on pharmacogenetic testing of TPMT and metabolite monitoring (MM) may offer a safety and efficacy advantage over traditional dosing strategies. We performed a decision analysis to estimate the potential costs and effectiveness of TPMT screening and MM as disease management strategies for CD. METHODS: Strategies applying TPMT and/or MM to influence treatment decisions were compared to community care (CC). The impact on toxicity minimization and improved time to initial and sustained response was evaluated. A 1-yr model was developed from the third-party payer perspective for mild to moderately chronically active, steroid-treated CD patients. Effectiveness and toxicity defined by time to response CD activity index (CDAI <150, +/- steroids) or time to sustained response (CDAI <150, off steroids x 8 wk) and reduction in leukopenic events, respectively. One- and two-way sensitivity analyses were conducted to determine the effect of varying individual estimates from those used in the base-case analysis. RESULTS: MM, TPMT, and TPMT + MM strategies as compared to CC achieved an earlier time to initial response (18.66, 18.96, and 19.10 vs. 22.41 wk, respectively) and sustained response (39.83, 42.91, and 39.8 vs. 45.36 wk, respectively). The least costly strategy at 1 yr was TPMT ($3,861) and the most costly strategy was CC ($7,142). Each alternative strategy was shown to dominate CC (i.e., less costs and faster time to response or sustained response). The cost-effectiveness rankings were robust to sensitivity analyses on key variables. CONCLUSION: The addition of alternative strategies to CC may improve AZA outcomes and reduce the total cost of care for steroid treated chronically active CD patients, with TPMT being more beneficial for initial response to treatment and MM being more beneficial for sustained response to treatment.     

Therapeutic efficacy and safety of 6-mercaptopurine and azathioprine in patients with Crohn's disease

The purine analogues 6-mercaptopurine (6-MP) and azathioprine have been found to be safe and efficacious in both inducing remission of Crohn's disease in adults and maintaining remission in adults and children. In addition, steroid-sparing effects are demonstrable in trials of both adults and children with Crohn's disease. Anecdotal reports of adults and very limited data from children also suggest that azathioprine and 6-MP might help prevent postoperative recurrence of Crohn's disease. Regarding safety, adults and children reported similar rates of adverse effects from the use of these agents: reported adverse effects in adults included significant infection (7.4%), pancreatitis (3.3%), neoplasm (3.1%), bone marrow suppression (2.0%), allergy (2.0%), and drug-induced hepatitis (0.3%). Most studies also suggest there is little, if any, probability that immunomodulatory therapy might increase the risk of malignancy in patients with Crohn's disease. Data are too limited to guide clinical decisions on how long immunomodulatory therapy should be continued, whether it is safe to take azathioprine and 6-MP during pregnancy, and whether men can take these agents at the time of conception. Although 6-MP and azathioprine have been used safely for over 30 years, the recent commercial availability of thiopurine methyltransferase (TPMT) genotype/phenotype testing and 6-MP metabolite testing offers the promise of limiting potential toxicity even more. As a result, these agents will continue to play a central therapeutic role for all clinicians caring for children or adults with Crohn's disease.     

Side effects of azathioprine in patients with Crohn's disease

OBJECTIVE: In clinical trials 0-15% of patients discontinued azathioprine due to side effects. The aim of this study was to assess the rate of side effects leading to discontinuation of azathioprine and to determine predictive factors for discontinuation. DESIGN: A retrospective cohort analysis of clinical data regarding adverse events of azathioprine in Crohn's disease. PATIENTS: Azathioprine had been prescribed for 54 of 112 consecutive patients with Crohn's disease. Because incomplete data were available in four patients, the data for 50 patients were analysed. RESULTS: In 15 of the 50 patients azathioprine was preliminary discontinued due to adverse events and in 11 of these patients (22%) adverse events were probably related to azathioprine. After the onset of therapy, a small, but significant, decrease in leucocyte count was observed within 6 weeks (median from 10.6 to 9.5 x 10(9)/l) and asymptomatic leucopenia (< 3.0 x 10(9)/l) occurred in two patients. Serious adverse events occurred in three patients who, as a result, required admission to hospital. All events were reversible after discontinuation of therapy. Patients who discontinued azathioprine due to adverse events used significantly lower initial doses of prednisone compared to patients who were able to continue azathioprine. The occurrence of side effects was not related to the initial dose of azathioprine or concomitant use of 5-aminosalicylates. CONCLUSION: Twenty-two per cent of patients discontinued azathioprine prematurely probably as a result of related adverse events. Patients who discontinued azathioprine prematurely used lower doses of prednisone initially. Therefore, concomitant use of prednisone may prevent some of the adverse events.     

A case of therapy-related myeloid neoplasm in a patient with Crohn's disease treated with azathioprine

The aim of the present study was to determine serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and leptin in patients with chronic myeloid leukemia (CML) at diagnosis and after imatinib therapy when patients achieved a complete molecular remission. The study was conducted on 22 patients with CML in the chronic phase and 10 healthy subjects. The median serum NGAL levels in CML patients at diagnosis were significantly higher compared to age-matched controls. After imatinib therapy, all patients achieved complete molecular remission and NGAL levels decreased and were found significantly lower with respect to the baseline. No significant correlations were found between NGAL levels and other disease parameters. Before imatinib therapy, the median blood leptin levels were not significantly different from those of controls. After therapy with imatinib, all patients in molecular remission presented an increase in leptin levels. Future research is eagerly awaited as it may demonstrate the real role of NGAL and leptin in the onset and progression of CML.     

Combining infliximab with 6-mercaptopurine/azathioprine for fistula therapy in Crohn's disease

OBJECTIVES: Fistulas occur in about one third of patients with Crohn's disease and rarely heal spontaneously. Conventional medical and surgical therapy often fails. The anti-TNF-alpha antibody infliximab offers a novel therapeutic option. By this approach, closure of fistulas was reported in 45% of cases. However, after discontinuation of therapy, most fistulas recurred. Azathioprine and 6-mercaptopurine (6-MP) are effective drugs in Crohn's disease and lead to closure of fistulas in 30-40% of cases. Thus, the aim of this study was to evaluate the combination of infliximab with 6-mercaptopurine/azathioprine as therapy for fistulas in patients with Crohn's disease. METHODS: A total of 16 patients (mean age 37 yr) with Crohn's fistulas resistant to conventional measures were treated with a combination of three or four infusions of infliximab and long term 6-MP/azathioprine. In all, 13 patients had perianal fistulas, two had abdominal fistulas, and one patient had both perianal and recto-vaginal fistulas. Therapy success was defined as complete closure of fistulas for a minimum observation period of 6 months after fistula closure. RESULTS: In 12 (75%) of the 16 patients, we observed complete closure of the fistulas that persisted for >6 months (median follow-up 10 months, range 6-11 months). The median time to complete closure of fistulas was 14 days (range 2-36 days). In four patients, therapy success was not achieved. CONCLUSION: Our pilot study reveals that concomitant and long term 6-MP/azathioprine therapy could prolong the effect of an initial infliximab therapy on fistula closure in patients with Crohn's disease. These data prompt larger controlled trials.     

Sustained improvement of health-related quality of life in Crohn's disease patients treated with infliximab and azathioprine for 4 years

BACKGROUND: Infliximab induces remission and improves the health-related quality of life (HRQOL) of patients with refractory or fistulous Crohn's disease (CD). However, little information is available as to whether its effect on HRQOL is sustained over time. The objective was to measure the HRQOL of CD patients in long-term clinical remission. METHODS: Prospective, observational study was undertaken in patients with CD in infliximab-induced clinical remission (Harvey index <3) for at least 6 months, and receiving long-term infliximab and azathioprine maintenance therapy. Patients were followed for 4 years or until clinical relapse (Harvey index >3). HRQOL was assessed annually using the validated Spanish version of the disease-specific 36-item Inflammatory Bowel Disease Questionnaire (IBDQ-36) and the EuroQol-5D. RESULTS: Forty-nine patients with CD in stable clinical remission were included at baseline. At 12 months, n = 42 patients remained in remission, at 24 months n = 32 patients, at 36 months n = 13, and in the last visit at 48 months 6 patients remained in clinical remission. The overall score on the IBDQ-36 remained unchanged in patients with stable, inactive CD (median overall score of 6.1 at baseline and 6.5 at 4 years). Scores on all 5 dimensions of the IBDQ-36 remained unchanged over the study period in stable patients. Patients in remission scored highly on the preference value ratings of the EuroQol-5D (scores of 1.0) and remained unchanged in patients who remained in remission. CONCLUSIONS: Sustained clinical remission of CD achieved with maintenance treatment maintains HRQOL over long-term follow-up.     

MDR1 polymorphisms and response to azathioprine therapy in patients with Crohn's disease

BACKGROUND: To investigate the contribution of multidrug resistance 1 (MDR1) gene pharmacogenetics (G2677T/A and C3435T) to the efficacy of azathioprine in inducing remission in patients with Crohn's disease (CD). METHODS: A cohort of 327 unrelated Spanish patients with CD recruited from a single center was studied. All patients were rigorously followed up for at least 2 years (mean time, 11.5 years). A case-control analysis of MDR1 G2677T/A and C3435T SNPs and 2 loci haplotypes in 112 steroid-dependent CD patients treated with azathioprine was performed. Patients were classified on the basis of response to azathioprine. RESULTS: A total 76 patients treated with azathioprine for longer than 3 months were included. Remission was achieved in 42 CD patients (55.3%). A higher frequency of the 2677TT genotype was found in nonresponders than in responders (17.65% versus 7.14%; OR = 2.8; 95% CI; 0.6-12.1; P = 0.11). Nonresponders to azathioprine were found to have a higher frequency of the 3435TT genotype than did CD patients who had achieved clinical remission (17.64% versus 4.76%; OR = 4.3; 95% CI, 0.8-22.8; P = 0.06). The 2677T/3435T haplotype was also more abundant in nonresponders (29.4% versus 20.2%), whereas the 2677G/3435C haplotype was more frequent in responders (58.3% versus 47.1%). Lack of response to azathioprine therapy in CD patients was 1.8-fold greater in carriers of the 2677T/3435T haplotype than in carriers of the 2677G/3435C haplotype (OR = 1.8; 95% CI, 0.82-3.9; P = 0.14). CONCLUSIONS: The results of our study indicate higher frequencies of the 2677TT and 3435TT genotypes and the 2677T/3435T haplotype in CD patients who did not respond to azathioprine. Additional replications in independent populations would confirm the real impact of these polymorphisms in response to azathioprine therapy.     

Safe treatment of thiopurine S-methyltransferase deficient Crohn's disease patients with azathioprine

Thiopurine S-methyltransferase (TPMT) deficient patients develop life threatening haematotoxicity (for example, pancytopenia) when treated with a standard dose of azathioprine (AZA) and 6-mercaptopurine (6-MP) due to excessive accumulation of cytotoxic metabolites. At present, it is generally recommended that these patients should not receive AZA or 6-MP treatment for inflammatory bowel disease. We report for the first time that Crohn's disease patients with TPMT deficiency can be successfully treated with AZA. We illustrate this with three cases where treatment has been successful and toxicity has been avoided by carefully titrating the drug dose. Thus very low TPMT activity demands pharmacogenetically guided dosing.     

Epstein-Barr virus-positive lymphoma in patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine.

BACKGROUND & AIMS: The use of azathioprine and 6-mercaptopurine for inflammatory bowel disease increased in the early 1990s. We sought to determine the effect of this change in therapy on the risk of lymphoma in patients with inflammatory bowel disease. METHODS: All patients with inflammatory bowel disease at a single tertiary care medical center who developed lymphoma between 1985-2000 were identified and the pathologic features of the lymphoma including presence of Epstein- Barr virus were determined. The patients were divided into two 8-year periods (1985-1992, 1993-2000) corresponding with the introduction of azathioprine and 6-mercaptopurine in 1993. RESULTS: Eighteen patients with lymphoma were identified, 6 between 1985-1992 and 12 between 1993-2000. Six of 18 lymphomas occurred in patients treated with azathioprine or 6-mercaptopurine, all between 1993-2000. Seven patients developed Epstein-Barr virus-positive lymphoma (1 from 1985-1992, 6 from 1993-2000). Five of 7 Epstein-Barr virus-positive lymphomas occurred in patients treated with azathioprine or 6-mercaptopurine compared with 1 of 11 Epstein-Barr virus-negative lymphomas (P = 0.01). Approximately 1200 patients with inflammatory bowel disease were treated with these agents between 1993-2000. CONCLUSIONS: Treatment of inflammatory bowel disease with azathioprine or 6-mercaptopurine appears to be associated with a small increased risk of Epstein-Barr virus-positive lymphoma.     

Efficacy of mycophenolate mofetil in patients failing 6-mercaptopurine or azathioprine therapy for Crohn's disease

Mycophenolate mofetil (MMF) is a novel immunomodulator that may be effective in the treatment of chronic active and perianal Crohn's disease (CD). The aim of this study is to assess the efficacy of MMF in CD patients who failed or were intolerant of 6-mercaptopurine (6-MP) or azathioprine (AZA). Eleven CD patients were treated with MMF after a failed course of 6-MP/AZA, and their records reviewed retrospectively. Reasons for 6-MP/AZA intolerance or failure were recorded. Response to MMF was determined by calculation of the Harvey-Bradshaw index and ability to taper steroids. Adverse reactions to MMF were recorded. Eleven patients were identified who failed a previous trial of 6-MP/AZA and other immunomodulators and required immunomodulator therapy. Of 11 patients who started MMF, four had early adverse reactions within 8 weeks and stopped the medication. Of the remaining seven patients who took MMF for at least 8 weeks, one had a complete response, two had a partial response, and four had no response to the medication. In patients who failed 6-MP/AZA, MMF was of benefit in 3 of 11 patients with only one complete responder. This lower-than-expected response rate may indicate that patients who are resistant to 6-MP or AZA may also be resistant to MMF.     

Bone mineral density in patients with Crohn's disease during long-term treatment with azathioprine

Florén C-H, Ahrén B, Bengtsson M, Bartosik J, Obrant K (Lund University, Malmö, Sweden). Bone mineral density in patients with Crohn's disease during long-term treatment with azathioprine. J Intern Med 1998; 243 : 123–26.

Objectives

To ascertain whether patients with Crohn's disease treated with azathioprine maintained bone mineral mass better than patients treated with steroids alone.

Design

Retrospective study.

Setting

University Hospital of Malmö, Sweden.

Subjects

A total of 59 patients with ileocolonic, ileocaecal or colonic Crohn's disease.

Methods

Bone mass was assessed by dual photon X-ray absorptiometry at the level of L2 – L4.

Results

Patients treated with a high lifetime dose of steroids (> 5 g prednisolone) had significantly (P= 0.011) lower Z-score of L₂–L₄ (?0.87 ± 1.11; 11 SD) than steroid-treated patients, who had received a low dose of prednisolone (< 5 g) (0.08 ± 1.16 SD). Azathioprine did not negatively influence the steroid effect on bone mineral density.

Conclusions

Azathioprine does not seem to affect bone mineral density by itself. However, by being steroid-saving, it seems to conserve bone mineral mass in patients with Crohn's disease.

     

Increased risk of lymphoma among inflammatory bowel disease patients treated with azathioprine and 6-mercaptopurine

BACKGROUND: Inflammatory bowel disease (IBD) is commonly treated with immunomodulators such as azathioprine and 6-mercaptopurine (6-MP). Studies examining lymphoma risk in IBD patients treated with these medications have been underpowered and have yielded conflicting conclusions. AIMS: The purpose of this meta-analysis was to provide a more precise estimate of the relative risk of lymphoma among IBD patients treated with azathioprine or 6-MP. METHODS: Studies were included if they were English language, full article, cohort studies specifically designed to evaluate cancer as an adverse outcome of treatment with azathioprine or 6-MP. Pooled standardised incidence ratios were calculated to estimate the relative risk of lymphoma associated with therapy. Heterogeneity was assessed using Poisson regression. Sensitivity analyses examined the influence of individual studies on risk estimate and heterogeneity statistics. RESULTS: Six studies were identified that met our inclusion criteria. When the data were combined across all studies, the pooled relative risk was 4.18 (95% confidence interval 2.07-7.51; 11 observed cases, 2.63 expected). Sensitivity analysis showed that exclusion of any one study had a relatively small effect on the pooled relative risk estimate (range 3.49-5.21) but excluding either the study with the highest or lowest estimated relative risk eliminated the statistically significant heterogeneity. CONCLUSIONS: Our data suggest an approximate fourfold increased risk of lymphoma in IBD patients treated with azathioprine/6-MP. The increased risk of lymphoma could be a result of the medications, the severity of the underlying disease, or a combination of the two.     

Neoplasia of the tongue in a patient with Crohn's disease treated with azathioprine: case report

Azathioprine is now widely used for the maintenance treatment of Crohn's disease, but there are concerns whether azathioprine could predispose to malignancy in patients with inflammatory bowel disease. We report here a case of a 39-year-old non-smoking male with Crohn's disease who had been treated for 3 years with azathioprine and developed a lingual ulcer. Biopsy revealed squamous cell carcinoma, a tumour not previously associated with Crohn's disease.     

TPMT in the treatment of Crohn's disease with azathioprine

Azathioprine induced profound myelosuppression linked to TPMT deficiency has now been documented in many patient groups, including those with Crohn's disease. At the start of azathioprine or mercaptopurine therapy, measurement of TPMT activity has a role in identifying the 1 in 300 patients who are at risk of severe myelosuppression when treated with standard thiopurine dosages. During the initial months of azathioprine therapy a knowledge of TPMT status warns of early bone marrow toxicity. In patients established on azathioprine these is no clear evidence to suggest that TPMT is predictive of clinical response or drug toxicity, indicating a role for TPMT in the prediction of early events rather than long term control. In patients with Crohn's disease on long term azathioprine therapy, it is clear that myelosuppression, particularly leucopenia, is caused by other factors in addition to variable TPMT activity and therefore monitoring of blood cell counts throughout treatment is essential.