A simple index relating clinical activity in Crohn's disease with T cell activation: hematocrit, frequency of liquid stools and urinary neopterin as parameters.

Crohn's disease is characterized by alternating acute and quiescent periods. Several indices for activity of the inflammatory process have been proposed to have criteria for prognosis of the clinical course and therapeutic efficacy. Neopterin is specifically released from human monocytes-macrophages after induction by interferon-gamma secreted from activated human T lymphocytes. Thus, urinary neopterin excretion is elevated in diseases involving activation of cellular immunity. Fifteen clinical and laboratory parameters, including urinary neopterin levels, collected from 35 visits of patients with Crohn's disease, were compared using multiple linear regression analysis with a simple clinical activity index as reference. Prediction of clinical activity was best with the combination of hematocrit, weekly number of liquid stools and neopterin. A simple triple-parametric Crohn's disease activity index was established on the basis of this result. Its quality was tested on independent data obtained from 25 repeat visits of 13 of these patients. A comparison with the well-known Crohn's Disease Activity Index (CDAI) was performed. The results obtained with the proposed activity index were slightly better than those with the eight-parametric CDAI for the data from the first as well as from the repeat visits. We conclude that our simple index is a reliable and easily accessible measure for clinical activity in patients with Crohn's disease.