The Cohen test does not predict outcome in achalasia after pneumatic dilation

The Cohen test has been recommended to evaluate the efficacy of pneumatic dilation of the lower esophageal sphincter in patients with achalasia. It consists of ingestion of 8 ounces of heavy barium. Upright radiographs are performed 5 minutes later to determine the height of the barium column in the esophagus in relation to the diaphragm. A column less than 1 cm above the diaphragm is a negative test indicating successful dilation and the high probability of dysphagia resolution. A positive Cohen test, a column exceeding 1 cm, is said to correlate with persistent symptoms and need for redilation. We evaluated this in a prospective manner for a 6-year period. Twenty-eight patients underwent standard technique pneumatic dilation at our institution. Achalasia was confirmed in all patients by way of upper endoscopy and manometry. A Cohen test was performed in all patients. Post-dilation symptoms and weight were analyzed at follow-up 6 weeks after dilation. Contrary to the original report, relief of dysphagia after dilation was not related to the results of the Cohen test (p = 0.77). A positive Cohen test was inversely correlated with both symptom duration (0.037) and lower esophageal sphincter pressure before dilation (p = 0.005). Weight gain after dilation was unrelated to Cohen test results (p = 0.67). We conclude that the Cohen test is not an accurate predictor of symptom relief after dilation and do not recommend its use to determine the end point of therapy in patients with achalasia.