CORR Insights®: Minimal Clinically Important Differences of the Hospital for Special Surgery Dysphagia and Dysphonia Inventory and Other Dysphagia Measurements in Patients Undergoing ACDF.

The number of anterior cervical spine operations in the United States is rising, with a 206% increase of use from 1992 to 2005 as reported among Medicare recipients [1, 11]. There has also been a national trend toward a greater utilization of the outpatient environment and same day operations. As such, it is crucial that we better understand the early complications following anterior cervical spine operations, such as anterior discectomy and fusion [12]. Dysphonia and dysphagia are known complications following anterior cervical procedures, but the frequency with which these complications occurs varies widely. For example, postoperative dysphagia occurs after 2% to 60% of patients who undergo anterior cervical discectomy and fusion [13]. Still, these postsurgical complications occur frequently enough that 68% of the 115 survey respondents from the Cervical Spine Research Society reported dysphagia as an expected and acceptable surgical complication [11]. To echo this sentiment, dysphonia and dysphagia are, in my experience, part of the preoperative discussions of most spinal surgeons and are presented, in at least some form, as something a patient should expect after surgery. The magnitude and duration of dysphonia and dysphagia after surgery are therefore pertinent to almost all patients, but these certainly are a greater concern for patients who are at increased risk, such as patients with multiple levels of surgery, longer durations of surgery, surgeries that are very cranial or caudal. A critical limitation of studies that evaluate dysphonia and dysphagia after anterior cervical discectomy and fusion is the lack of a validated, quantitative, easy to use, and universally accepted measures of dysphonia and dysphagia. For that reason, the current study by Okano et al. [6] is so important. This study determined the minimum clinically important difference (MCID) for the Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) to be 11 of 100 points for the distribution-based approach and 9 of 100 points for the anchor-based approach [6]. The two accepted methods to determine MCID the authors chose were the distribution-based approach (in which measurement error drives the minimal detectable change) as well as an anchor-based approach (which uses an independent external anchor question with good face validity, and which clinicians and patients believe would reasonably be responsive the presence or absence of symptoms [3]). Anchorbased approaches may be both more familiar and more helpful to clinicians, as they consider whether observed effects in a research study are large enough to care about [4]. This CORR Insights is a commentary on the article “Minimum Clinically Important Differences of the Hospital for Special Surgery Dysphagia and Dysphonia Inventory and Other Dysphagia Measurements in Patients Undergoing ACDF” by Okano and colleagues available at: DOI: 10. 1097/CORR.0000000000001236. The author certifies that neither he, nor any members of his immediate family, have any commercial associations (such as consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. The opinions expressed are those of the writer, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. W. F. LavelleMD (✉), SUNYUpstateMedical University, Department of Orthopedic Surgery, 750 E. Adams St. Syracuse, NY 13210, USA, Email: lavellew@upstate.edu