Correlation of various Crohn's disease activity indexes in subgroups of patients with primarily inflammatory or fibrostenosing clinical characteristics.

Several activity indexes, including clinical variables, laboratory variables or both, have been proposed to assess the activity and severity of Crohn's disease (CD). Although activity indexes are commonly used in clinical trials, doubts exist as to whether it is correct to group together and quantify under the same numerical expression the very heterogeneous clinical manifestations of CD. The aim of our study was to try to establish a correlation between clinical and laboratory activity indexes of CD in subgroups of patients with primarily inflammatory or primarily fibrostenosing clinical characteristics. At least two activity indexes were calculated among 232 outpatient examinations in 61 CD patients. Indexes were classified as clinical, laboratory, or both. A close correlation was observed when indexes calculated on clinical variables were compared or when those that include only or prevalently laboratory parameters were compared. Conversely, the correlation between clinical and laboratory indexes tended to be poor. Taking into consideration the subgroups of patients, the correlation between clinical and laboratory indexes was high in primarily inflammatory disease but low in the primarily fibrostenosing form. The clinical activity of CD does not always reflect the quantity of inflammation measured by laboratory parameters. This is particularly true in primarily fibrostenosing disease. Different clinical patterns of CD should always be considered in the attempt to quantify with an activity index the activity and severity of disease.