Which clinical variables predict an abnormal double-contrast barium enema result?

To determine the relations among patient history, symptoms, objective indicators, and abnormal double-contrast barium enema results in outpatients.

Seven hundred and ninety-four patients receiving care in a large multispecialty medical group.

Physicians completed a form before ordering a double-contrast barium enema, listing information about patient history, symptoms, and objective findings, including the results of a complete blood count, stool hemoccult, and sigmoidoscopy.

Outcome measures were colon cancer and any abnormal finding. The results of 18.6% of the barium enemas were abnormal. The most frequent positive findings were of polyps (8.8%) and colon cancer (2.9%). Over 50% of the barium enemas were ordered solely on the basis of symptoms, yet there was no statistical correlation between symptoms and colon cancer or any positive finding. Using logistic regression, four variables were shown to be significant predictors of colon cancer (P less than 0.05): abnormal sigmoidoscopy, iron deficiency anemia, positive stool hemoccult results, and relevant history. The respective odds ratios of these variables were 3.76 (95% CI, 2.89 to 4.90); 2.86 (CI, 2.13 to 3.74); 1.87 (CI, 1.46 to 2.39); and 1.91 (CI, 1.44 to 2.52), respectively. In a patient without any of these indicators, the predicted probability of having colon cancer was only 0.7%. In a patient with at least two objective indicators, the probability of having colon cancer was greater than 15%.

Symptoms without objective indicators or pertinent risk factors do not correlate with an abnormal double-contrast barium enema result. Objective indicators are useful predictors of an abnormal barium enema result, particularly when looking for colon cancer.