Risk factors for anemia in patients with ileal pouch-anal anastomosis

Anemia is frequently observed in patients with ileal pouch-anal anastomosis. The identification of the underlying causes can be challenging. This study was designed to define the prevalence and to identify etiologic factors for anemia in this patient population.

A prospectively maintained database and medical records of patients who had restorative proctocolectomy between 1998 and 2005 were reviewed. All patients with laboratory evaluation at least six months after the surgery were studied. The last reported hemoglobin served as the index value. All patients with anemia (hemoglobin < 13.5 g/dl for males, <12 g/dl for females) were identified. A second group of randomly selected, ileal-pouch patients with normal hemoglobin served as control. Demographic and clinical variables were evaluated.

A total of 389 patients (214 males) had documented hemoglobin values. Sixty-seven patients (17 percent; 40 males) had anemia. The prevalence of anemia was 19 and 15 percent in males and females, respectively. The prevalence was 17 percent among patients with underlying ulcerative colitis vs. 26 percent in patients with familial adenomatous polyposis (P = 0.27). The mean hemoglobin in the anemia group was 11.4 (median, 11.7) g/dl. One patient (2 percent) had severe (<7 g/dl), 11 (16 percent) had moderate (7-9.9 g/dl), and 55 (82 percent) had mild (> or =10 g/dl) anemia. One patient (2 percent) had macrocytic, 16 (24 percent) had microcytic, and 49 (74 percent) had normocytic anemia. Sixteen patients (24 percent) had unidentified causes for anemia. Multivariable analysis showed that the presence of malignancy or desmoid tumor and the J-pouch configuration were the only independent risk factors associated with anemia.

Anemia is common in ileal-pouch patients. Malignancy or desmoid tumor and J-pouch configuration are independent risk factors for anemia. One-fourth of the patients with anemia have unclear etiology.