Screening for anemia in patients on warfarin facilitates diagnosis of gastrointestinal malignancies and pre-malignant lesions.

Abstract

The prevalence and etiology of occult bleeding among patients on warfarin who are screened systematically for new anemia is largely unknown. We aimed to estimate the usefulness of following hemoglobin and mean red cell volume (MCV) with INR in order to screen for developing anemia as an indicator of occult bleeding. All patients on warfarin controlled at our institution had measurements of complete blood count (CBC) with INR during 18 months. Patients who fell>25 g/L and/or decrease of MCV over 5 fL or MCV<80 fL were contacted with instructions to undergo evaluation of anemia. Overall 3218 patients on warfarin were monitored at our institution and 442 (13.7%) had anemia and 235 (7.3%) had unexplained anemia. A total of 163/235 (69%) who were notified contacted their doctors and 82/163 (50%) were referred for investigation with upper and/or lower endoscopies. Gastrointestinal malignancies were found in 11 patients (10 colorectal cancers, 1 esophageal) and pre-cancerous lesions among 14 other patients. Additional 25/82 patients (30%) had upper and/or lower bleeding lesions such as ulcers and angiodysplasia. Based on 3669 years of observation, 73 patients needed to be screened for one year in order to identify one gastrointestinal lesion causing occult bleeding. Thirty percent of those endoscoped had malignant or pre-malignant diseases. Regular measurement of CBC concomitantly with INR in patients on warfarin therapy led to detection of otherwise asymptomatic diseases in a significant proportion of patients and might lead to earlier diagnosis of malignant and premalignant disease.