Clinical utility of the 3-ounce water swallow test

Abstract

The 3-ounce water swallow test is frequently used to screen individuals for aspiration risk. Prior research concerning its clinical usefulness, however, is confounded by inadequate statistical power due to small sample sizes and varying methodologies. Importantly, research has been limited to a few select patient populations, thereby limiting the widespread generalizability and applicability of the 3-ounce test. The purpose of this study was to investigate the clinical utility of the 3-ounce water swallow test for determining aspiration status and oral feeding recommendations in a large and heterogeneous patient population. Fiberoptic endoscopic evaluation of swallowing (FEES) was performed in conjunction with the 3-ounce water swallow test on 3000 participants with a wide range of ages and diagnoses. A total of 1151 (38.4%) passed and 1849 (61.6%) failed the 3-ounce water swallow test. Sensitivity of the 3-ounce water swallow test for predicting aspiration status during FEES = 96.5%, specificity = 48.7%, and false positive rate = 51.3%. Sensitivity for identifying individuals who were deemed safe for oral intake based on FEES results = 96.4%, specificity = 46.4%, and false positive rate = 53.6%. Passing the 3-ounce water swallow test appears to be a good predictor of ability to tolerate thin liquids. However, failure often does not indicate inability to tolerate thin liquids, i.e., low specificity and high false-positive rate. Use of the 3-ounce water swallow test alone to make decisions regarding safety of liquid intake results in over-referral and unnecessary restriction of liquid intake for nearly 50% of patients tested. In addition, because 71% of participants who failed the 3-ounce water swallow test were deemed safe for an oral diet, nonsuccess on the 3-ounce water swallow test is not indicative of swallowing failure. The clinical utility of the 3-ounce water swallow test has been extended to include a wide range of medical and surgical diagnostic categories. Importantly, for the first time it has been shown that if the 3-ounce water swallow test is passed, diet recommendations can be made without further objective dysphagia testing.