Utility assessment to measure the impact of dry eye disease

Utility assessment is a formal method for quantifying and understanding the relative impact of a given health state or disease on patients. In this article, methodology of utility assessment is explained and illustrated, and results of an original study are reported. The study was conducted to determine utility values (patient preferences) associated with dry eye disease and compare them to other disease utilities, as well as to compare patient and physician assessments of disease. Forty-four patients in the United Kingdom with moderate to severe dry eye were surveyed via interactive utility assessment software. Utility values were measured by the Time Trade-Off (TTO) and Standard Gamble (SG) methods and adjusted to scores from 1.0=perfect health to 0.0=death. Patients reported utilities for: self-reported current dry eye status, self-reported current comorbidities, various dry eye severities, and binocular and monocular painful blindness. Patient's dry eye severity was independently classified by patient and physician assessments. Correlation analyses (Pearson) were performed between patients' current dry eye utilities and the physician-assessed severity. Agreement between self-reported and physician-reported patient severity was analyzed (Kappa). Patients reported higher utilities for their current dry eye condition than for monocular and binocular blindness (SG:0.84>0.60>0.51; TTO:0.67>0.43>0.38). Using TTO, the mean score for asymptomatic dry eye (0.68) was similar to that for "some physical and role limitations with occasional pain" and severe dry eye requiring surgery scored (0.56) similarly to hospital dialysis (0.56-0.59) and severe angina (0.5). Utilities described for scenarios of dry eye severity levels were slightly higher for patients self-reported as mild-to-moderate versus those self-reported as severe. For current dry eye condition, mean utilities for these groups were 0.72 for self-reported mild-to-moderate and 0.61 for self-reported severe. Utilities for dry eye were in the range of conditions accepted as lowering health utilities. Severe dry eye utilities were similar to those reported for dialysis and severe angina, highlighting the impact of dry eye disease on patients.