“…Because no International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) diagnostic code for vocal fold fibrosis or scarring currently exists, we designed proxy inclusion criteria whereby patients were required to have had a surgical procedure known to result in clinically significant vocal fold mucosal volumetric loss, fibrosis, and glottal incompetence. [33][34][35] We focused on the following procedures: 1) partial laryngectomy with a resection margin that included the vocal fold mucosa (Healthcare Common Procedure Coding System [HCPCS] 31375, 31380, 31382; ICD-9-CM 30.2, 30.29, 30.1, 30.22); and 2) direct laryngoscopy with vocal fold stripping (HCPCS 31540, 31541; ICD-9-CM 30.09), when coded alongside a vocal fold leukoplakia or cancer diagnosis (ICD-9-CM 161.0, 161.2, 161.8, 161.9, 231.0, 478.5). These specific procedure-diagnosis combinations (in this study collectively referred to as the index procedure) were implemented to capture surgical procedures with sufficiently sized resection margins to result in a high likelihood of dysphonia.…”