Determining the Minimal Clinically Important Difference of the UNC Dry Eye Management Scale

BACKGROUND: Dry eye disease (DED) is a common, chronic ocular surface disease affecting millions of Americans; it can severely diminish quality of life (QOL). Many patient-reported outcomes (PRO) questionnaires have been developed to assess DED, but few have established a minimal clinically important difference (MCID) in accordance with FDA guidelines. OBJECTIVE: To establish an initial estimation of the MCID of the UNC Dry Eye Management Scale (DEMS) and assess patient perceptions of symptom change versus score change. METHODS: I recruited 33 patients who had a prior DEMS score from a UNC ophthalmology cornea clinic in Chapel Hill, NC for study in the months of May and June 2014. I compared patients' change in the DEMS scores from the most recent prior visit to patient-reported assessments of change in symptoms at the time of this study. Using anchor-based methods to determine an MCID, I obtained linear regression coefficients from the comparison to be my estimation of the MCID. I also recorded clinical assessments of the patients' disease severity, and I administered another questionnaire to assess patient perceptions of score change as it relates to symptom change. RESULTS: All 33 patients in this first attempt to establish MCID were included in analysis (33.3% male, 67.7% female, mean age 60.5 years). Anchors were correlated with DEMS score changes. The MCID ranged from ½ point using linear regression analysis to 1 point using descriptive statistics. Patients felt that a change of approximately 2 points was needed to represent an improvement/worsening of symptoms. The UNC DEMS had modest correlations with clinical tests. CONCLUSIONS: The UNC DEMS is a valid, responsive PRO instrument that can be used easily in the clinic to aid in the management of dry eye disease over time.Master of Public Healt