Factors associated with short- and long-term outcomes of therapy for Crohn's disease

Our post hoc analysis assessed the association of early (at weeks 26-30) clinical, endoscopic, biologic, and pharmacokinetic outcomes with corticosteroid-free remission at week 50 (CSFR50); CSFR50 was observed in 55.2% and 65.4% of patients treated with infliximab, alone or in combination with azathioprine, respectively.

We analyzed data from 203 patients: 96 received infliximab monotherapy and 107 received combination therapy. Receiver operating characteristic analysis was used to set cut-off points for the week 30 trough serum infliximab concentration (SIC30) and percentage change, from baseline, in the C-reactive protein (CRP) level at week 26, to predict CSFR50. Univariate and multivariate procedures analyzed predictive parameters of CSFR50 (odds ratio [OR] and 95% confidence interval [CI]). Mucosal healing (MH, zero ulcers) and CRP normalization (<8.0 mg/L) also were assessed.

Trough SIC30 was higher in patients with than without CSFR50. Patients given combination therapy had higher trough SIC30s than those given monotherapy. Median trough SIC30 was significantly higher in patients with than without CSFR50 among those on infliximab monotherapy (2.14 vs 0.80 μg/mL; P = .006), but not for those on combination therapy (3.56 vs 3.54 μg/mL; P=.31). In patients with increased baseline levels of CRP (n = 120), corticosteroid-free remission at week 26 (CSFR26) (OR, 4.09; 95% CI, 1.65-10.11), and trough SIC30s of 3.0 μg/mL or greater (OR, 3.20; 95% CI, 1.38-7.42) were associated significantly with CSFR50. In patients evaluable for MH (n = 123), trough SIC30s of 3.0 μg/mL or greater (OR, 3.34; 95% CI, 1.53-7.28) and CRP normalization (OR, 2.69; 95% CI, 1.10-6.54) were associated significantly with MH at week 26 (MH26). Furthermore, CSFR26 (OR, 4.43; 95% CI, 1.81-10.82) and MH26 (OR, 3.01; 95% CI, 1.33-6.81) were associated significantly with CSFR50.

Trough SIC30 is associated positively with MH26; CSFR26 and MH26 are independent predictors of CSFR50. Trough SIC30 of 3.0 μg/mL or greater early during maintenance treatment is an important determinant of clinical and endoscopic Crohn's disease outcomes. ClinicalTrials.gov number, NCT00094458.