RECTOSIGMOID INFLAMMATORY LESIONS AND ITS DETERMINANTS IN PATIENTS WITH ANKYLOSING SPONDYLITIS

Introduction: Ankylosing Spondylitis (AS) is a chronic and systemic inflammatory disease which mainly affects the axial skeleton. There are substantial evidences that risk of rectosigmoid inflammation is increased in patients with AS. Subclinical inflammation could be associated with significant complications; understanding of its prevalence is an important step towards (developing measures to improve) both early diagnosis and selection of the most appropriate treatment strategies. We have studied the prevalence of the rectosigmoid inflammation and its associated risk factors in patient with AS.

Materials and Methods:  In this cross-sectional study ,110 patients who have the diagnosis of AS based on the Assessment of New York classification where enrolled. The severity of AS based on AS disease activity (ASDAS-CRP) Score was also calculated. Patients who were on biological agents or Sulfasalazine were excluded. Written  informed consent was obtain from all patients. Demographic data, smoking history, time since diagnosis, disease severity, axial versus axial and peripheral involvement, HLA B27 status, latest CRP and ESR level and also fecal Calprotectin were collected. All patients underwent rectosigmoidoscopy and biopsy. Data analysis was done using SPSS software( Ver 18).

Results: 87(79.1%) patients were male and 23(20.9%) were  females. The mean  age was 41.46±11.81. year.  The mean time since diagnosis was 6.49±7.16 year.. 54.5% of patients were non-smoker. 84% of patients had other organs involvement. Out of 110 patients, 57(51.8%) had axial only and the rest had both axial and peripheral involvement. Calprotectin level was increased in 94% of patients and the mean level was92.81±40.7. The mean CRP and ESR level was 34.22±25 and 35.89±25.54 respectively. 39.1% of patients were HLA27 positive. Severity of AS in most of patients was in intermediate range (36.4%). In 37 patients( 33.6%) the rectosigmoid macroscopically looked abnormal. The microscopic assessment of the samples showed inflammatory bowel disease in 15.5%, chronic non-specific inflammationin 49.1% and was normal in 31.8%. There was a significant relationship between age,CRP,fecal calprotectin and macroscopic and microscopic findings  (p value for age: 0.001 and 0.005), (p values for fecal calprotectin: 0.0001 and 0.008), (pvalues for CRP :0.0001 and 0.008). The relationship between macroscopic findings and severity of AS (p value 0.008) and time since diagnosis (p value 0.015) was statistically significant.

Conclusion: This study showed  that older age, severity of AS, high fecal Calprotectin level and high CRP are associated with presence of inflammatory rectosigmoid  disease and could be used as a important determinant for  early diagnosis of this lesion in  patients with AS.