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P240. Predicting response to thiopurines – A single centre experience

G. Costantino1, F. Furfaro1, A. Alibrandi2, W. Fries1

1Department of Internal Medicine, University of Messina, Italy; 2Department of Economical, Financial, Social, Environmental, Statistical and Territorial Sciences, University of Messina, Italy

Azathoprine (AZA) and 6-mercaptopurine (6-MP) are widely used in inflammatory bowel disease (IBD). The main drawbacks of thiopurine therapy are the slow onset of action and the difficulty to predict efficacy of therapy.

The aim of the present study was to assess predictors and indicators of clinical response beyond the use of clinical scores in both, Crohn's disease (CD) and ulcerative colitis (UC).

Methods: We analyzed retrospectively our patients charts and identified 266 patients treated ever with thiopurines. From 139 of them (CD: 75, male 39; UC: 64, male 37), data concerning disease activity (Harvey-Bradshaw index, HBI; or partial Mayo score, pMS), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), erythrocyte count (RBC), mean corpuscular volume (MCV), leucocyte count (WBC), neutrophil count (NBC) were available prior to start of thiopurines and at 6 months. Duration of disease, smoking status, body mass index (BMI), dose/kg of AZA/6-MP were registered at baseline. The above variables were analyzed with respect to response (R) to therapy (defined as: no need of surgery, oral steroids or biologics at 6 months after start therapy) and non response (NR). Data are mean values ± SD. Analysis was performed with Mann-Whitney and Wilcoxon test and logistic regression.

Results: Data were available from 96 R (54 CD, 42 UC) and 43 NR (21 CD, 22 UC). Clinical activity indices in R fell significantly in both, CD (HBI from 6.5±3.5 to 2.6±1.4, p < 0.001) and UC (pMS from 5.4±2.9 to 1.1±1.0, p < 0.001), but not in NR. The mean daily dose for AZA was 1.98 mg/kg ±0.47 and for 6-MP 1.17 mg/kg ±0.48. (From the examined variables significant (p < 0.001) drops were registered for CRP, ESR, WBC, and NBC in R, but only for WBC in NR. In both groups MCV increased significantly (p < 0.001, both). Additionally in NR a decrease (p < 0.02) of RBC was noted. Neither BMI (p = 0.886) nor smoking status (p = 0.744) nor daily dose (p = 0.530) did influence response to therapy. Patients with shorter duration of disease responded better to therapy (p = 0.007).

Conclusions: CRP, ESR and neutrophil count are useful markers to predict clinical response to thiopurines therapy in IBD patients, whereas the increase of MCV did not distinguish between R and NR. Early use of thiopurines was associated with better response to therapy.