Determination of the Minimal Clinically Important Difference of the University of North Carolina Dry Eye Management Scale
To establish an initial estimation of the MCID of the University of North Carolina Dry Eye Management Scale (UNC DEMS) and assess its association with patient perceptions of symptom change.Methods:
Thirty-three patients (33.3% men, 67.7% women, mean age 60.5 yrs) with previous DEMS scores were recruited from a UNC ophthalmology clinic in spring 2014. We used anchor-based methods, categorizing important symptom change, to compare the change in the DEMS scores across visits to patient assessments of change; linear regression coefficients estimated the MCID. We correlated clinical assessments, patient perceptions, and DEMS scores.Results:
DEMS score changes correlated with global anchors [−0.4229 (P = 0.014)]. Unadjusted linear regression yielded a beta coefficient of −0.54 (confidence interval, −0.97 to −0.12, R2 = 0.18, P = 0.014), which estimated the DEMS MCID. Adjusting the regression model for days since the last visit and DEMS score improved the association (beta = −0.56; confidence interval, −0.99 to −0.13; R2 = 0.43; P = 0.013). Descriptive statistics produced an MCID of 1 point. Patients said that 2 points would represent a significant change. The DEMS modestly correlated with the Schirmer test (−0.4045, P = 0.0266), Oxford Grading Scheme (+0.3713, P = 0.0364), and tear breakup time (−0.3559, P = 0.0456).Conclusions:
The UNC DEMS is a valid, responsive patient-reported outcome measure instrument, which is easy to use in the clinic and capable of showing an MCID of 1 point.