The benefit of concomitant immunomodulation with adalimumab (ADA) in Crohn's disease is poorly understood. We aimed to compare ADA monotherapy with combination therapy with thiopurines, stratified by thioguanine nucleotides (TGNs).Methods:
Retrospective observational study of ADA induction and maintenance. Thiopurines were classified according to TGNs (>235 pmol/8 × 108 red blood cell therapeutic).Results:
At induction, response was more frequent in combination than ADA monotherapy (83% versus 61%, P = 0.02) and with therapeutic compared with subtherapeutic TGNs (87% versus 70% P = 0.011). Among 280 maintenance semesters in 91 patients, remission was higher with combination than monotherapy (81% versus 60%, P < 0.0001) and therapeutic versus subtherapeutic TGNs (85% versus 58%, P = 0.004). Therapeutic TGN (odds ratio [OR] 4.32, 95% CI, 1.41–13.29, P = 0.01) and albumin (OR 1.09, 95% CI, 1.01–1.18, P = 0.03) were predictors of response to induction. Therapeutic TGN (OR 3.71, 95% CI, 1.87–7.34, P < 0.0001) and ileal disease (OR 0.21, 95% CI, 0.08–0.57, P = 0.002) were predictors of remission semesters. Concomitant immunomodulation at induction was associated with longer time to failure (69 versus 36 months, P = 0.009). Therapeutic TGN at induction (P = 0.03) and male sex (P = 0.026) were associated with time to failure.Conclusions:
Combination therapy was superior to ADA monotherapy for induction and during maintenance. This benefit was increased further when thiopurines resulted in therapeutic TGNs. Early use of adequately dosed thiopurines (≥3 months before starting ADA) was associated with improved clinical outcomes.