Figure 4.

Receiver operating characteristic curves for C3-percentage of prevertebral soft tissue swelling C4-percentage of prevertebral soft tissue swelling at 2 or 3 days after surgery. An increase in percentage of prevertebral soft tissue swelling is a valid diagnostic indicator to predict the incidence of postoperative dysphagia. The area under the curve in C3-percentage of prevertebral soft tissue swelling and C4- percentage of prevertebral soft tissue swelling was 0.773 and 0.762, respectively. C3-percentage of prevertebral soft tissue swelling at 2 or 3 days after surgery of 71% was considered to be the good diagnostic cutoff value and had 58% sensitivity and 89% specificity, while C4-percentage of prevertebral soft tissue swelling at 2 or 3 days after surgery of 77% had 83% sensitivity and 66% specificity