Azathioprine or 6-mercaptopurine for maintenance of remission in Crohn's disease

BACKGROUND

The therapeutic role of 6-mercaptopurine (6-MP) and azathioprine (AZA) remains controversial due to their perceived relatively slow-acting effect and adverse effects. An updated meta-analysis was performed to evaluate the efficacy of these agents for the maintenance of remission in quiescent Crohn's disease.

OBJECTIVES

To assess the efficacy of AZA and 6-MP for maintenance of remission in quiescent Crohn's disease.

SEARCH METHODS

We searched MEDLINE, EMBASE, and the Cochrane Library from inception to June 30, 2015.

SELECTION CRITERIA

Randomized controlled trials of oral azathioprine or 6-mercaptopurine compared to placebo or active therapy involving adult patients (> 18 years) with quiescent Crohn's disease were considered for inclusion. Patients with surgically-induced remission were excluded.

DATA COLLECTION AND ANALYSIS

At least two authors independently extracted data and assessed study quality using the Cochrane risk of bias tool. For dichotomous outcomes, we calculated the risk ratio (RR) and corresponding 95% confidence interval (CI). The primary outcomes was maintenance of remission. Secondary outcomes included steroid sparing, adverse events, withdrawals due to adverse events and serious adverse events. All data were analyzed on an intention-to-treat basis. The overall quality of the evidence supporting the primary outcome and selected secondary outcomes was assessed using the GRADE criteria.

MAIN RESULTS

Eleven studies (881 participants) were included. Comparisons included AZA versus placebo (7 studies, 532 participants), AZA or 6-MP versus mesalazine or sulfasalazine (2 studies, 166 participants), AZA versus budesonide (1 study, 77 participants), AZA and infliximab versus infliximab (1 study, 36 patients), 6-MP versus methotrexate (1 study, 31 patients), and early AZA versus conventional management (1 study, 147 participants). Two studies were rated as low risk of bias. Three studies were rated as high risk of bias for being non-blinded. Six studies were rated as unclear risk of bias. A pooled analysis of six studies (489 participants) showed that AZA (1.0 to 2.5 mg/kg/day) was significantly superior to placebo for maintenance of remission over a 6 to 18 month period. Seventy-three per cent of patients in the AZA group maintained remission compared to 62% of placebo patients (RR 1.19, 95% CI 1.05 to 1.34). The number needed to treat for an additional beneficial outcome was nine. A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was low due to sparse data (327 events) and unclear risk of bias. A pooled analysis of two studies (166 participants) showed no statistically significant difference in the proportion of patients who maintained remission between AZA (1.0 to 2.5 mg/kg/day) or 6-MP (1.0 mg/day) and mesalazine (3 g/day) sulphasalazine (0.5 g/15 kg) therapy. Sixty-nine per cent of patients in the AZA/6-MP group maintained remission compared to 67% of mesalazine/sulphasalazine patients (RR 1.09, 95% CI 0.88 to 1.34). A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was low due to sparse data (113 events) and high or unclear risk of bias. One small study found AZA (2.0 to 2.5 mg/kg/day) to be superior to budesonide (6 to 9 mg/day) for maintenance of remission at one year. Seventy-six per cent (29/38) of AZA patients maintained remission compared to 46% (18/39) of budesonide patients (RR 1.65, 95% CI 1.13 to 2.42). GRADE indicated that the overall quality of the evidence supporting this outcome was low due to sparse data (47 events) and high risk of bias. One small study found no difference in maintenance of remission rates at one year between combination therapy with AZA (2.5 mg/kg) and infliximab (5 mg/kg every 8 weeks) compared to infliximab monotherapy. Eighty-one per cent (13/16) of patients in the combination therapy group maintained remission compared to 80% (16/20) of patients in the infliximab group (RR 1.02, 95% CI 0.74 to 1.40). GRADE indicated that the overall quality of the evidence supporting this outcome was very low due to very sparse data (29 events) and unclear risk of bias. One small study found no difference in maintenance of remission rates at one year between 6-MP (1 mg/day) and methotrexate (10 mg/week). Fifty per cent (8/16) of 6-MP patients maintained remission at one year compared to 53% (8/15) of methotrexate patients (RR 0.94, 95% CI 0.47 to 1.85). GRADE indicated that the overall quality of the evidence supporting this outcome was very low due to very sparse data (16 events) and high risk of bias. One study (147 participants) failed to show any significant benefit for early azathioprine treatment over a conventional management strategy. In the early azathioprine treatment group 67% (11-85%) of the trimesters were spent in remission compared to 56% (29-73%) in the conventional management group. AZA when compared to placebo had significantly increased risk of adverse events (RR 1.29, 95% CI 1.02 to 1.64), withdrawal due to adverse events (3.12, 95% CI 1.59 to 6.09) and serious adverse events (RR 2.45, 95% CI 1.22 to 4.90). AZA/6-MP also demonstrated a significantly higher risk of serious adverse events when compared to mesalazine or sulphasalazine (RR 9.37, 95% CI 1.84 to 47.7). AZA/6-MP did not differ significantly from other active therapies with respect to adverse event data. Common adverse events included pancreatitis, leukopenia, nausea, allergic reaction and infection.

AUTHORS' CONCLUSIONS

Low quality evidence suggests that AZA is more effective than placebo for maintenance of remission in Crohn's disease. Although AZA may be effective for maintenance of remission its use is limited by adverse effects. Low quality evidence suggests that AZA may be superior to budesonide for maintenance of remission but because of small study size and high risk of bias, this result should be interpreted with caution. No conclusions can be drawn from the other active comparator studies because of low and very low quality evidence. Adequately powered trials are needed to determine the comparative efficacy and safety of AZA and 6-MP compared to other active maintenance therapies. Further research is needed to assess the efficacy and safety of the use of AZA with infliximab and other biologics and to determine the optimal management strategy for patients quiescent Crohn's disease.

Vedolizumab for induction and maintenance of remission in ulcerative colitis

BACKGROUND

Cellular adhesion molecules play an important role in the pathogenesis of ulcerative colitis, making selective blockade of these molecules a promising therapeutic strategy. Vedolizumab, a recombinant humanized IgG1 monoclonal antibody, inhibits adhesion and migration of leukocytes into the gastrointestinal tract by binding the alpha4beta7 integrin. Animal studies have suggested that vedolizumab may be a useful therapy for ulcerative colitis. This updated systematic review summarizes the current evidence on the use of vedolizumab for induction and maintenance of remission in ulcerative colitis.

OBJECTIVES

The primary objectives were to determine the efficacy and safety of vedolizumab used for induction and maintenance of remission in ulcerative colitis.

SEARCH METHODS

A computer-assisted search for relevant studies (inception to 15 June 2014) was performed using PubMed, MEDLINE, EMBASE and CENTRAL. References from published articles and conference proceedings were searched to identify additional citations.

SELECTION CRITERIA

Randomized controlled trials comparing vedolizumab to placebo or a control therapy for induction or maintenance of remission in ulcerative colitis were included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the risk of bias for each trial. The primary outcomes were failure to induce clinical remission and relapse. Secondary outcomes included failure to induce a clinical response, failure to induce endoscopic remission, failure to induce an endoscopic response, quality of life, adverse events, serious adverse events and withdrawal due to adverse events. We calculated the relative risk (RR) and 95% confidence intervals (CI) for each outcome. Data were analyzed on an intention-to-treat basis. The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria.

MAIN RESULTS

Four studies (606 patients) were included. All of the studies were rated as having a low risk of bias. Pooled analyses revealed that vedolizumab was significantly superior to placebo for induction of remission, clinical response, and endoscopic remission and prevention of relapse. After 4 to 6 weeks of therapy 77% (293/382) of vedolizumab patients failed to enter clinical remission compared to 92% (205/224) of placebo patients (RR 0.86, 95% CI 0.80 to 0.91; 4 studies 606 patients). After 6 weeks of therapy 48% of vedolizumab patients failed to have a clinical response compared to 72% of placebo patients (RR 0.68, 95% CI 0.59 to 0.78; 3 studies 601 patients). After 4 to 6 weeks of therapy 68% of vedolizumab patients failed to enter endoscopic remission compared to 81% of placebo patients (RR 0.82, 95% CI 0.75 to 0.91; 3 studies, b583 patients). After 52 weeks of therapy, 54% of vedolizumab patients had a clinical relapse compared to 84% of placebo patients (RR 0.67, 95% CI 0.59 to 0.77; 1 study, 373 patients). One small study (28 patients) found no statistically significant difference in endoscopic response (RR 1.00, 95% CI 0.62 to 1.61). GRADE analyses indicated that the overall quality of the evidence for the primary outcomes was high for induction of remission and moderate for relapse (due to sparse data 246 events). There was no statistically significant difference between vedolizumab and placebo in terms of the risk of any adverse event (RR 0.99, 95% CI 0.93 to 1.07), or serious adverse events (RR 1.01, 95% CI 0.72 to 1.42). There was a statistically significant difference in withdrawals due to adverse events. Six per cent of vedolizumab patients withdrew due to an adverse event compared to 11% of placebo patients (RR 0.55, 95% CI 0.35 to 0.87; 2 studies, 941 patients). Adverse events commonly reported across the studies included: worsening ulcerative colitis, headache, nasopharyngitis, upper respiratory tract infection, nausea, and abdominal pain.

AUTHORS' CONCLUSIONS

Moderate to high quality data from four studies shows that vedolizumab is superior to placebo for induction of clinical remission and response and endoscopic remission in patients with moderate to severely active ulcerative colitis and prevention of relapse in patients with quiescent ulcerative colitis. Moderate quality data from one study suggests that vedolizumab is superior to placebo for prevention of relapse in patients with quiescent ulcerative colitis. Adverse events appear to be similar to placebo. Future trials are needed to define the optimal dose, frequency of administration and long-term efficacy and safety of vedolizumab used for induction and maintenance therapy of ulcerative colitis. Vedolizumab should be compared to other currently approved therapies for ulcerative colitis in these trials.

Methotrexate for induction of remission in refractory Crohn's disease

BACKGROUND

Although corticosteroids are effective for induction of remission of Crohn's disease, many patients relapse when steroids are withdrawn or become steroid dependent. Furthermore, corticosteroids exhibit significant adverse effects. The success of methotrexate as a treatment for rheumatoid arthritis led to its evaluation in patients with refractory Crohn's disease. Methotrexate has been studied for induction of remission of refractory Crohn's disease and has become the principal alternative to azathioprine or 6-mercaptopurine therapy. This systematic review is an update of previously published Cochrane reviews.

OBJECTIVES

The primary objective was to assess the efficacy and safety of methotrexate for induction of remission in patients with active Crohn's disease in the presence or absence of concomitant steroid therapy.

SEARCH METHODS

We searched MEDLINE, EMBASE, CENTRAL and the Cochrane IBD/FBD group specialized register from inception to June 9, 2014 for relevant studies. Conference proceedings and reference lists were also searched to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials of methotrexate compared to placebo or an active comparator for treatment of active refractory Crohn's disease in adult patients (> 17 years) were considered for inclusion.

DATA COLLECTION AND ANALYSIS

The primary outcome was failure to enter remission and withdraw from steroids. Secondary outcomes included adverse events, withdrawal due to adverse events, serious adverse events and quality of life. We calculated the relative risk (RR) and 95% confidence intervals (95% CI) for each outcome. Data were analyzed on an intention-to-treat basis. The Cochrane risk of bias tool was used to assess the methodological quality of included studies. The GRADE approach was used to assess the overall quality of evidence supporting the primary outcome.

MAIN RESULTS

Seven studies (495 patients) were included. Four studies were rated as low risk of bias. Three studies were rated as high risk of bias due to open label or single-blind designs. The seven studies differed with respect to participants, intervention, and outcomes to the extent that meta-analysis was considered to be inappropriate. GRADE analyses indicated that the quality of evidence was very low to low for most outcomes due to sparse data and inadequate blinding. Three small studies which employed low dose oral methotrexate showed no statistically significant difference in failure to induce remission between methotrexate and placebo or between methotrexate and 6-mercaptopurine. For the study using 15 mg/week of oral methotrexate 33% (5/15) of methotrexate patients failed to enter remission compared to 11% (2/18) of placebo patients (RR 3.00, 95% CI 0.68 to 13.31). For the study using 12.5 mg/week of oral methotrexate 81% (21/26) of methotrexate patients failed to enter remission compared to 77% (20/26) of placebo patients (RR 1.05, 95% CI 0.79 to 1.39). This study also had an active comparator arm, 81% (21/26) of methotrexate patients failed to enter remission compared to 59% (19/32) of 6-mercaptopurine patients (RR 1.36, 95% CI 0.97 to 1.92). For the active comparator study using 15 mg/week oral methotrexate, 20% (3/15) of methotrexate patients failed to enter remission compared to 6% of 6-mercaptopurine patients (RR 3.20, 95% CI 0.37 to 27.49). This study also had a 5-ASA arm and found that methotrexate patients were significantly more likely to enter remission than 5-ASA patients. Twenty per cent (3/15) of methotrexate patients failed to enter remission compared to 86% (6/7) of 5-ASA patients (RR 0.23, 95% CI 0.08 to 0.67). One small study which used a higher dose of intravenous or oral methotrexate (25 mg/week) showed no statistically significant difference between methotrexate and azathioprine. Forty-four per cent (12/27) of methotrexate patients failed to enter remission compared to 37% of azathioprine patients (RR 1.20, 95% CI 0.63 to 2.29). Two studies found no statistically significant difference in failure to enter remission between the combination of infliximab and methotrexate and infliximab monotherapy. One small study utilized intravenous methotrexate (20 mg/week) for 5 weeks and then switched to oral (20 mg/week). Forty-five per cent (5/11) of patients in the combination group failed to enter remission compared to 62% of infliximab patients (RR 0.73, 95% CI 0.31 to 1.69). The other study assessing combination therapy utilized subcutaneous methotrexate (maximum dose 25 mg/week). Twenty-four per cent (15/63) of patients in the combination group failed to enter remission compared to 22% (14/63) of infliximab patients (RR 1.07, 95% CI 0.57 to 2.03). A large placebo-controlled study which employed a high dose of methotrexate intramuscularly showed a statistically significant benefit relative to placebo. Sixty-one per cent of methotrexate patients failed to enter remission compared to 81% of placebo patients (RR 0.75, 95% CI 0.61 to 0.93; number needed to treat, NNT=5). Withdrawals due to adverse events were significantly more common in methotrexate patients than placebo in this study. Seventeen per cent of methotrexate patients withdrew due to adverse events compared to 2% of placebo patients (RR 8.00, 95% CI 1.09 to 58.51). The incidence of adverse events was significantly more common in methotrexate patients (63%, 17/27) than azathioprine patients (26%, 7/27) in one small study (RR 2.42, 95% CI 1.21 to 4.89). No other statistically significant differences in adverse events, withdrawals due to adverse events or serious adverse events were reported in any of the other placebo-controlled or active comparator studies. Common adverse events included nausea and vomiting, abdominal pain, diarrhea, skin rash and headache.

AUTHORS' CONCLUSIONS

There is evidence from a single large randomized trial which suggests that intramuscular methotrexate (25 mg/week) provides a benefit for induction of remission and complete withdrawal from steroids in patients with refractory Crohn's disease. Lower dose oral methotrexate does not appear to provide any significant benefit relative to placebo or active comparator. However, these trials were small and further studies of oral methotrexate may be justified. Comparative studies of methotrexate to drugs such as azathioprine or 6-mercaptopurine would require the randomization of large numbers of patients. The addition of methotrexate to infliximab therapy does not appear to provide any additional benefit over infliximab monotherapy. However these studies were relatively small and further research is needed to determine the role of methotrexate when used in conjunction with infliximab or other biological therapies.

Azathioprine or 6-mercaptopurine for induction of remission in Crohn's disease

BACKGROUND

The results from controlled clinical trials investigating the efficacy of azathioprine and 6-mercaptopurine for the treatment of active Crohn's disease have been conflicting and controversial. An updated meta-analysis was performed to assess the effectiveness of these drugs for the induction of remission in active Crohn's disease.

OBJECTIVES

The primary objective was to determine the efficacy and safety of azathioprine and 6-mercaptopurine for induction of remission in active Crohn's disease.

SEARCH METHODS

A literature search for relevant studies (inception to June 13, 2012) was performed using MEDLINE, EMBASE and the Cochrane Library. Review articles and conference proceedings were also searched to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of oral azathioprine or 6-mercaptopurine compared to placebo or active therapy involving adult patients with active Crohn's disease were selected for inclusion.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent observers based on the intention-to-treat principle. Outcomes of interest included: clinical remission, clinical improvement, fistula improvement or healing, steroid sparing, adverse events, withdrawals due to adverse events and serious adverse events. We calculated the pooled relative risk (RR) and 95% confidence intervals (95% CI) for each outcome. The methodological quality of included studies was evaluated using the Cochrane risk of bias tool. The overall quality of the evidence supporting each outcome was assessed using the GRADE criteria.

MAIN RESULTS

Thirteen RCTs (n = 1211 patients) of azathioprine and 6-mercaptopurine therapy in adult patients were identified: nine included placebo comparators and six included active comparators. The majority of included studies were rated as low risk of bias. There was no statistically significant difference in clinical remission rates between azathioprine or 6-mercaptopurine and placebo. Forty-eight per cent (95/197) of patients receiving antimetabolites achieved remission compared to 37% (68/183) of placebo patients (5 studies, 380 patients; RR 1.23, 95% CI 0.97 to 1.55). There was no statistically significant difference in clinical improvement rates between azathioprine or 6-mercaptopurine and placebo. Forty-eight per cent (107/225) of patients receiving antimetabolites achieved clinical improvement or remission compared to 36% (75/209) of placebo patients (8 studies, 434 patients; RR 1.26, 95% CI 0.98 to 1.62). There was a statistically significant difference in steroid sparing (defined as prednisone dose < 10 mg/day while maintaining remission) between azathioprine and placebo. Sixty-four per cent (47/163) of azathioprine patients were able to reduce their prednisone dose to < 10 mg/day compared to 46% (32/70) of placebo patients (RR 1.34, 95% CI 1.02 to 1.77). GRADE analyses rated the overall quality of the evidence for the outcomes clinical remission, clinical improvement and steroid sparing as moderate due to sparse data. There was no statistically significant difference in withdrawals due to adverse events or serious adverse events between antimetabolites and placebo. Ten percent of patients in the antimetabolite group withdrew due to adverse events compared to 5% of placebo patients (8 studies, 510 patients; RR 1.70, 95% CI 0.94 to 3.08). Serious adverse events were reported in 14% of patients receiving azathioprine compared to 4% of placebo patients (2 studies, 216 patients; RR 2.57, 95% CI 0.92 to 7.13). Common adverse events reported in the placebo controlled studies included: allergic reactions. leukopenia, pancreatitis and nausea. Azathioprine was significantly inferior to infliximab for induction of steroid-free clinical remission. Thirty per cent (51/170) of azathioprine patients achieved steroid-free remission compared to 44% (75/169) of infliximab patients (1 study, 339 patients; RR 0.68, 95% CI 0.51 to 0.90). The combination of azathioprine and infliximab was significantly superior to infliximab alone for induction of steroid-free clinical remission. Sixty per cent (116/194) of patients in the combined azathioprine and infliximab group achieved steroid-free remission compared to 48% (91/189) of infliximab patients (2 studies, 383 patients; RR 1.23, 95% CI 1.02 to 1.47). Azathioprine or 6-mercaptopurine therapy was found to be no better at inducing steroid free clinical remission compared to methotrexate (RR 1.13, 95% CI 0.85 to 1.49) and 5-aminosalicylate or sulfasalazine (RR 1.24, 95% CI 0.80 to 1.91). There were no statistically significant differences in withdrawals due to adverse events between azathioprine or 6-mercaptopurine and methotrexate (RR 0.78, 95% CI 0.23 to 2.71); between azathioprine or 6-mercaptopurine and 5-aminosalicylate or sulfasalazine (RR 0.98, 95% CI 0.38 to 2.54); between azathioprine and infliximab (RR 1.47, 95% CI 0.96 to 2.23); or between the combination of azathioprine and infliximab and infliximab (RR 1.16, 95% CI 0.75 to 1.80). Common adverse events in the active comparator trials included nausea, abdominal pain, pyrexia and headache.

AUTHORS' CONCLUSIONS

Azathioprine and 6-mercaptopurine offer no advantage over placebo for induction of remission or clinical improvement in active Crohn's disease. Antimetaboilte therapy may allow patients to reduce steroid consumption. Adverse events were more common in patients receiving antimetabolites although differences with placebo were not statistically significant. Azathioprine therapy is inferior to infliximab for induction of steroid-free remission. However, the combination of azathioprine and infliximab was superior to infliximab alone for induction of steroid-free remission.

Methotrexate for induction of remission in refractory Crohn's disease

BACKGROUND

Although corticosteroids are effective for induction of remission of Crohn's disease, many patients relapse when steroids are withdrawn or become steroid dependent. Furthermore, corticosteroids exhibit significant adverse effects. The success of methotrexate as a treatment for rheumatoid arthritis led to its evaluation in patients with refractory Crohn's disease. Methotrexate has been studied for induction of remission of refractory Crohn's disease and has become the principal alternative to azathioprine or 6-mercaptopurine therapy. This systematic review is an update of a previously published Cochrane review.

OBJECTIVES

The primary objective was to assess the efficacy and safety of methotrexate for induction of remission in patients with active Crohn's disease in the presence or absence of concomitant steroid therapy.

SEARCH METHODS

We searched MEDLINE, EMBASE, CENTRAL and the Cochrane IBD/FBD group specialized register from inception to June 27, 2012 for relevant studies. Conference proceedings and reference lists were also searched to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials of methotrexate compared to placebo or an active comparator for treatment of active refractory Crohn's disease in adult patients (> 17 years) were considered for inclusion.

DATA COLLECTION AND ANALYSIS

The primary outcome was failure to failure to enter remission and withdrawal from steroids. Secondary outcomes included adverse events, withdrawal due to adverse events, serious adverse events and quality of life. We calculated the relative risk (RR) and 95% confidence intervals (95% CI) for each outcome. Data were analyzed on an intention to treat basis. The Cochrane risk of bias tool was used to assess the methodological quality of included studies. The GRADE approach was used to assess the overall quality of evidence supporting the primary outcome.

MAIN RESULTS

Seven studies (495 patients) were included. Four studies were rated as low risk of bias. Three studies were rated as high risk of bias due to open label or single-blind designs. The seven studies differed with respect to participants, intervention, and outcomes to the extent that it was considered to be inappropriate to pool the data for meta-analysis. Three small studies which employed low doses of oral methotrexate showed no statistically significant difference in failure to induce remission between methotrexate and placebo or between methotrexate and 6-mercaptopurine. For the study using 15 mg/week of oral methotrexate 33% (5/15) of methotrexate patients failed to enter remission compared to 11% (2/18) of placebo patients (RR 3.00, 95% CI 0.68 to 13.31). For the study using 12.5 mg/week of oral methotrexate 81% (21/26) of methotrexate patients failed to enter remission compared to 77% (20/26) of placebo patients (RR 1.05, 95% CI 0.79 to 1.39). This study also had an active comparator arm, 81% (21/26) of methotrexate patients failed to enter remission compared to 59% (19/32) of 6-mercaptopurine patients (RR 1.36, 95% CI 0.97 to 1.92). For the active comparator study using 15 mg/week oral methotrexate, 20% (3/15) of methotrexate patients failed to enter remission compared to 6% of 6-mercaptopurine patients (RR 3.20, 95% CI 0.37 to 27.49). This study also had a 5-ASA arm and found that methotrexate patients were significantly more likely to enter remission than 5-ASA patients. Twenty per cent (3/15) of methotrexate patients failed to enter remission compared to 86% (6/7) of 5-ASA patients (RR 0.23, 95% CI 0.08 to 0.67). One small study which used a higher dose of intravenous or oral methotrexate (25 mg/week) showed no statistically significant difference between methotrexate and azathioprine. Forty-four per cent (12/27) of methotrexate patients failed to enter remission compared to 37% of azathioprine patients (RR 1.20, 95% CI 0.63 to 2.29). Two studies found no statistically significant difference in failure to enter remission between the combination of infliximab and methotrexate and infliximab monotherapy. One small study utilized intravenous methotrexate (20 mg/week) for 5 weeks and then switched to oral (20 mg/week). Forty-five per cent (5/11) of patients in the combination group failed to enter remission compared to 62% of infliximab patients (RR 0.73, 95% CI 0.31 to 1.69) The other study assessing combination therapy utilized subcutaneous methotrexate (maximum dose 25 mg/week). Twenty-four per cent (15/63) of patients in the combination group failed to enter remission compared to 22% (14/63) of infliximab patients (RR 1.07, 95% CI 0.57 to 2.03). A large placebo-controlled study which employed a high dose of methotrexate intramuscularly showed a statistically significant benefit relative to placebo. Sixty-one per cent of methotrexate patients failed to enter remission compared to 81% of placebo patients (RR 0.75, 95% CI 0.61 to 0.93; number needed to treat, NNT=5). Withdrawals due to adverse events were significantly more common in methotrexate patients than placebo in this study. Seventeen per cent of methotrexate patients withdrew due to adverse events compared to 2% of placebo patients (RR 8.00, 95% CI 1.09 to 58.51). The incidence of adverse events was significantly more common in methotrexate patients (63%, 17/27) than azathioprine patients (26%, 7/27) in one small study (RR 2.42, 95% CI 1.21 to 4.89). No other statistically significant differences in adverse events, withdrawals due to adverse events or serious adverse events were reported in any of the other placebo-controlled or active comparator studies. Common adverse events included nausea and vomiting, abdominal pain, diarrhea, skin rash and headache.

AUTHORS' CONCLUSIONS

There is evidence from a single large randomized trial which suggests that intramuscular methotrexate (25 mg/week) provides a benefit for induction of remission and complete withdrawal from steroids in patients with refractory Crohn's disease. Lower dose oral methotrexate does not appear to provide any significant benefit relative to placebo or active comparator. However, these trials were small and further studies of oral methotrexate may be justified. Comparative studies of methotrexate to drugs such as azathioprine or 6-mercaptopurine would require the randomization of large numbers of patients. The addition of methotrexate to infliximab therapy does not appear to provide any additional benefit over infiximab monotherapy. However these studies were relatively small and further research is needed to determine the role of methotrexate when used in conjunction with infliximab or other biological therapies.

Azathioprine and 6-mercaptopurine for maintenance of remission in ulcerative colitis

BACKGROUND

Maintenance of remission is a major issue in inflammatory bowel disease. In ulcerative colitis, the evidence for the effectiveness of azathioprine and 6-mercaptopurine for the maintenance of remission is still controversial.

OBJECTIVES

To assess the effectiveness and safety of azathioprine and 6-mercaptopurine for maintaining remission of ulcerative colitis.

SEARCH METHODS

The MEDLINE, EMBASE and Cochrane Library databases were searched from inception to June 2012. A manual search was also performed using references from these articles as well as review articles, and proceedings from major gastrointestinal meetings. Authors of maintenance trials were asked about unpublished studies.

SELECTION CRITERIA

Randomized controlled trials of at least 12 months duration that compared azathioprine or 6-mercaptopurine with placebo or standard maintenance therapy (e.g. mesalazine) were included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data using standard forms. Disagreements were solved by consensus including a third author. Study quality was assessed using the Cochrane risk of bias tool. The primary outcome was failure to maintain clinical or endoscopic remission. Secondary outcomes included adverse events and withdrawal due to adverse events. Analyses were performed separately by type of control (placebo, or active comparator). Pooled risk ratios were calculated based on the fixed-effect model unless heterogeneity was shown. The GRADE approach was used to assess the overall quality of evidence for pooled outcomes.

MAIN RESULTS

Six studies including 286 patients with ulcerative colitis were included in the review. The risk of bias was high in three of the studies due to lack of blinding. Azathioprine was shown to be significantly superior to placebo for maintenance of remission. Fourty-four per cent (51/115) of azathioprine patients failed to maintain remission compared to 65% (76/117) of placebo patients (4 studies, 232 patients; RR 0.68, 95% CI 0.54 to 0.86). A GRADE analysis rated the overall quality of the evidence for this outcome as low due to risk of bias and imprecision (sparse data). Two trials that compared 6-mercaptopurine to mesalazine, or azathioprine to sulfasalazine showed significant heterogeneity and thus were not pooled. Fifty per cent (7/14) of 6-mercaptopurine patients failed to maintain remission compared to 100% (8/8) of mesalamine patients (1 study, 22 patients; RR 0.53, 95% CI 0.31 to 0.90). Fifty-eight per cent (7/12) of azathioprine patients failed to maintain remission compared to 38% (5/13) of sulfasalazine patients (1 study, 25 patients; RR 1.52, 95% CI 0.66 to 3.50). One small study found that 6-mercaptopurine was superior to methotrexate for maintenance of remission. In the study, 50% (7/14) of 6-mercaptopurine patients and 92% (11/12) of methotrexate patients failed to maintain remission (1 study, 26 patients; RR 0.55, 95% CI 0.31 to 0.95). All of the studies which used active comparators were open label. When placebo and active comparator studies were pooled to assess adverse events, there was no statistically significant difference between azathioprine and control in the incidence of adverse events. Nine per cent (11/127) of azathioprine patients experienced at least one adverse event compared to 2% (3/130) of placebo patients (5 studies, 257 patients; RR 2.82, 95% CI 0.99 to 8.01). Patients receiving azathioprine were at significantly increased risk of withdrawing due to adverse events. Eight per cent (8/101) of azathioprine patients withdrew due to adverse events compared to 0% (0/98) of control patients (5 studies, 199 patients; RR 5.43, 95% CI 1.02 to 28.75). Adverse events related to study medication included acute pancreatitis (3 cases) and significant bone marrow suppression (5 cases). Deaths, opportunistic infection or neoplasia were not reported.

AUTHORS' CONCLUSIONS

Azathioprine therapy appears to be more effective than placebo for maintenance of remission in ulcerative colitis. Azathioprine or 6-mercaptopurine may be effective as maintenance therapy for patients who have failed or cannot tolerate mesalazine or sulfasalazine and for patients who require repeated courses of steroids. More research is needed to evaluate superiority over standard maintenance therapy, especially in the light of a potential for adverse events from azathioprine. This review updates the existing review of azathioprine and 6-mercaptopurine for maintenance of remission in ulcerative colitis which was published in the Cochrane Library (Issue 1, 2007).