A HIGH SERUM CONCENTRATION OF INTERLEUKIN-6 IS PREDICTIVE OF RELAPSE IN QUIESCENT CROHNS-DISEASE

Background/aims: Relapses of Crohn's disease are difficult to predict. We assessed the value of serum level of interleukin-6, tumour necrosi s factor alpha (TNF-alpha) and soluble TNF receptors as predictors of relapse in quiescent Crohn's disease. Patients/methods: Thirty-six pat ients with inactive Crohn's disease, treated or not, were included. Va rious clinical and biological parameters, including interleukin-6, TNF -alpha and soluble TNF receptors serum levels were measured at inclusi on in the study and the patients were followed clinically for 1 year. The relapse was defined as a Crohn's Disease Activity Index (CDAI) gre ater than 150 with an increase greater than 100 compared to the inclus ion value. We analysed the ability of these parameters to predict rela pse in parallel to clinical characteristics and other laboratory param eters. Results: Among the 32 variables tested, interleukin-6 serum lev el had the greatest ability to predict the time-to-relapse, with 17-fo ld chance of relapse over a 1-year period for patients with an interle ukin-6 serum level greater than 20 pg/ml than for patients with a lowe r level ( P< 0.001). A high serum level of the soluble TNF receptors p 55 and p75 also had significant predictive value, in contrast to TNF-a lpha serum levels. An interleukin-6 serum level greater than 20 pg/ml and either an acid alpha-1-glycoprotein level greater than 1.1 g/l or a soluble interleukin-2 receptor serum level greater than 95 pM/l were risk factors selected by a stepwise multivariate analysis. In both mo dels a good prognosis group was defined by the absence of the two risk factors, a bad prognostic group by the presence of the two risk facto rs and an intermediate in between. With both models, the good prognosi s group included 17 patients who experienced no relapse over the 1-yea r follow-up, whereas all patients (seven with the first model and six with the second) in the bad prognosis group had a relapse during the f ollow-up. Looking specifically at two homogeneous subgroups including either naturally/5-aminosalicylic acid (5-ASA) quiescent or corticoid quiescent patients, a very good predictive value for interleukin-6 ser um concentration was also found. Conclusion: Interleukin-6 serum level alone or in association with other biological parameters such as acid alpha-1-glycoprotein or the soluble interleukin-2 receptor serum leve l may be useful for predicting the course of the disease in patients w ith quiescent Crohn's disease.