Relationship of common laboratory parameters to the activity of Crohn's disease in children

The Pediatric Crohn's Disease Activity Index (PCDAI) has been proposed as a simple instrument to aid in the classification of patients by disease severity. The PCDAI includes subjective patient reporting of symptoms, physical examination, nutritional parameters, and several common laboratory tests (hematocrit, erythrocyte sedimentation rate, albumin). In this report we examine the relationship of each of the laboratory parameters to the PCDAI, as well as to a modified Harvey-Bradshaw Index score and physician global assessment of disease activity. Data were gathered from the clinical and laboratory observations from 133 children and adolescents at 12 pediatric gastroenterology centers in North America. A statistically significant relationship (p less than 0.05) was noted between each of the laboratory tests and the PCDAI for patients with either disease limited to the small bowel or in those with colonic involvement. For patients with disease limited to the small bowel, a statistically significant (p less than 0.05) relationship was also noted between the three laboratory parameters and the modified Harvey-Bradshaw Index and global assessment. For patients with large-bowel involvement, the erythrocyte sedimentation rate was statistically related to the modified Harvey-Bradshaw Index and global assessment (p less than 0.01), as was hematocrit to global assessment (p less than 0.01). Although the laboratory parameters used in the PCDAI appear to generally reflect disease activity in most patients, no single laboratory test is adequate to reflect disease activity in all patients. Future work will need to identify additional laboratory measures to reflect the inflammatory process and serve as important adjuncts in the assessment of disease activity.