Faecal calprotectin in the assessment of Crohn's disease activity.
BACKGROUND
Clinical and laboratory assessment of activity in Crohn's disease (CD) correlate poorly with endoscopic findings. Calprotectin is a calcium-binding protein abundant in neutrophil cytosol, and extremely stable in faeces. Faecal calprotectin (FC) is an excellent surrogate marker of neutrophil influx into the bowel lumen.


OBJECTIVE
To assess whether FC concentration from a spot stool sample reliably detects active inflammation in patients with CD.


METHODS
Cross-sectional comparative study.


METHODS
Subjects had a previously confirmed diagnosis of CD and were suspected on clinical grounds to be in the midst of a relapse. Thirty-five entered the study; they underwent radiolabelled white cell scanning (WCS) and had a stool sample collected for calprotectin measurement on the same day. A Crohn's disease activity index (CDAI) was also calculated for each. The WCS scans were scored at six standard sites to give a mean total, 'extent', 'severity' and 'combined extent and severity' scores.


RESULTS
FC was significantly and positively correlated with mean total (r = 0.73, p < 0.001), 'extent' (r = 0.71, p < 0.001), 'severity' (r = 0.64, p < 0.001) and combined 'extent and severity' WCS scores (r = 0.71, p < 0.001). A cut-off of faecal calprotectin > 100 microg/g gave a sensitivity of 80%, specificity of 67%, positive predictive value of 87% and a negative predictive value of 64% in identifying those with and without any inflammation on WCS. There was, however, no significant correlation between CDAI and mean total WCS score (r = 0.21, p = 0.24), nor between CDAI and FC (r = 0.33, p = 0.06).


CONCLUSIONS
While the CDAI does not accurately reflect inflammatory activity in CD, a one-off FC reliably detects the presence or absence of intestinal inflammation in adult patients with CD, compared to WCS.
Gaya
D R
DR
Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, UK. danielgaya@aol.com
Lyon
T D B
TD
Duncan
A
A
Neilly
J B
JB
Han
S
S
Howell
J
J
Liddell
C
C
Stanley
A J
AJ
Morris
A J
AJ
Mackenzie
J F
JF
D000328:Adult; D015415:Biomarkers / Q000032:analysis; D003424:Crohn Disease / Q000175:diagnosis* / Q000378:metabolism; D003430:Cross-Sectional Studies; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex