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P226 Consistently high C reactive protein is associated with subsequent development of perianal fistulae in patients with Crohn's disease.

G. Radford-Smith*1, E. Ferguson2, K. Hanigan3, L. Simms3, J. Irwin1

1Royal Brisbane and Women's Hospital, Gastroenterology, Brisbane, Australia, 2Royal Brisbane & Women's Hospital, Department of Gastroenterology, Brisbane, Australia, 3QIMR Berghofer Medical Research Institute, Complex Diseases, Brisbane, Australia


Laboratory tests are used longitudinally in the management of patients with Crohn's disease. Whether there is a correlation between longitudinal laboratory Results and the subsequent development of perianal disease is unknown.

AIM: To study the correlation between longitudinal laboratory testing and subsequent development of perianal fistula in patients with Crohn's disease.


Patients diagnosed at a tertiary referral centre with Crohn's disease between 1994 and 2014, with more than five years of clinical follow-up, had objective clinical, laboratory and genetic data recorded. Patients with a perianal fistula occurring within 6 months of diagnosis were excluded. Laboratory data were represented by the area under the curve of values measured in the complication free period leading up to development of a perianal fistula. Cox regression was used to analyse the association between development of a perianal fistula and laboratory values for: C reactive protein (CRP), platelet count, albumin level, faecal calprotectin, serum ferritin, serum haemoglobin and erythrocyte sedimentation rate (ESR). Laboratory values were converted to categorical variables with optimized cut-offs. Recognized predictors of development of perianal disease were added to the model to assess independence of identified associations.


382 patients were reviewed, of whom 57 had less than five years of clinical follow-up and 43 had perianal disease within 6 months of diagnosis. 257 had a complete clinical, biochemical and genetic record without perianal disease at diagnosis and were observed for a median of 10.25 (interquartile range (IQR) 7.39-13.78) years. 46 patients developed a perianal fistula a median of 2.06 (IQR 1.10 - 5.82) years after diagnosis. Blood testing was performed a median of 3.61 (IQR 2.24 - 5.79) times per year for each patient. Results of univariate analysis are tabulated.

After multivariate analysis with inclusion of recognised predictor variables, CRP >31 (HR 7.12, p<0.001) and age at diagnosis <32 (HR 3.93, p=0.004) were independently associated with development of perianal fistula.

Table of laboratory tests.

VariableCut-offHazard ratiop-value
CRP>31 mg/L6.96<0.001**
ESR>14 mm/hr2.92<0.001**
Albumin<39 g/L3.12<0.001**
Platelets>270 x 10^9/L4.64<0.001**
Haemaglobin<137 g/L (m) <122 g/L (f)2.070.019
Ferritin<64 mcg/L3.270.030
Faecal calprotectin>192mcg/LNot able to calculate0.028


A longitudinally measured CRP consistently greater than 31 is independently associated with subsequent development of a perianal fistula in patients with Crohn's disease. Serial monitoring and a longitudinal analytic tool for serial CRPs may aid in identifying patients at risk of developing perianal disease.