Abstract
Purpose:
Dry eye disease (DED), a common, chronic disease that diminishes quality of life (QOL), is poorly managed given the poor correlation of patient-reported symptom severity and clinician-observed disease severity. The UNC Dry Eye Management Scale (DEMS) was developed to improve DED management. The first aim of this study was to translate the UNC DEMS to Spanish and to conduct a feasibility and comprehensibility study of this Spanish DEMS in a Spanish-speaking population. A second aim was to perform initial validity and reliability testing of the Spanish DEMS. This study helps meet the urgent need for valid, reliable patient reported outcome measures (PROM) in languages other than English.
Methods:
To develop the Spanish DEMS, we used a cross-cultural adaptation method similar to the universal translation method recommended by proponents of PROM translation. Native bilingual speakers performed forward, back, and forward translations, later reconciled by a team. Pre-testing and cognitive interviewing were done in a pilot sample of 13 Spanish-speaking DED patients. I administered the Spanish DEMS to these patients and used cognitive interviewing to evaluate the questionnaire’s comprehensibility and utility as an indicator of the effect of symptoms on QOL. I also obtained clinical assessments of disease severity (Schirmer’s test, tear break-up time, Oxford grading scheme, and clinician-reported overall assessment).
Results:
Cognitive interviewing validated the translation. Patients understood and agreed with the wording of the questionnaire. To test internal validity, I compared Spanish DEMS scores to disease severity. Spearman’s correlation coefficients showed weak degrees of correlation, as expected given the poor correlation of symptom severity and disease severity; the direction of the correlations was appropriate. To test external validity, I compared performance on the Spanish DEMS to performance on the English DEMS for patients of similar disease severity using the Mann-Whitney test. Performance on the two language versions was significantly similar in the mild-to-moderate and severe disease categories. While strictly illustrative, initial analysis was promising for the future validation of the Spanish DEMS.
Conclusions:
The early stages of our research confirm the Spanish UNC DEMS is an easy to use, easy to understand questionnaire that can improve the management of Spanish-speaking DED patients.