The utility of strabismus in adults

Abstract

Purpose: To determine the utility (quality-of-life weight) associated with adult strabismus.

Methods: Time tradeoff utility values were measured in physician-conducted interviews with 140 adult patients with strabismus in a private practice setting. Patients also completed a questionnaire containing six items that rated the following aspects of disability: specific health problems, problems with tasks of daily living, problems with social interaction, self-image problems, concerns about the future, and job-related problems. Patients were characterized as presurgical or nonsurgical, and their diplopia and asthenopia were rated by the physician on a four-level scale.

Results: About 60% of all patients indicated willingness to trade part of their life expectancy in return for being rid of strabismus and its associated effects. The median utility was 0.93 (interquartile range, 0.83 to 1.0). A significantly smaller proportion (44%) of the nonsurgical patients (N = 41) appeared willing to trade time compared with surgical patients (68%; P = .009). Median utility in the presurgical patients was 0.90. Strong relationships were found between utility and the level of diplopia (P < .0001), and between utility and the level of asthenopia (P < .0001). Utility was correlated with all six disability ratings (all P < or = .00062).

Conclusion: A majority of the patients interviewed would trade a portion of their life expectancy in return for being rid of strabismus and its associated effects. These results were validated by significant associations with diplopia, asthenopia, and disability.

FIGURE 1

Histogram showing the overall distribution of time tradeoff utility values in 140 consecutive adults with strabismus. The median of this distribution equals 0.93 (interquartile range, 0.83 to 1.0). A total of 85 patients (61%) indicated that they would be willing to trade part of their life expectancy in return for being rid of strabismus and all its associated effects. The remaining 55 patients returned a time tradeoff utility of 1 (ie, not willing to trade part of their life expectancy). Dark and light portions of each bar indicate the proportion of presurgical and nonsurgical patients, respectively

FIGURE 2

Box plots showing the relationship between time tradeoff utility in adults with strabismus and the physician ratings of each patient’s level of diplopia (top: 1 = None, 2 = In side gaze and/or upgaze only, 3 = In primary gaze and/or downgaze, 4 = Constant) and asthenopia (bottom: 1 = None, 2 = With prolonged effort, 3 = With minimal effort, 4 = Constant). In each box plot, the filled circle corresponds to the median utility, and the box spans the interquartile range (25th percentile to 75th percentile).

FIGURE 3

Scatter plots showing the relationships between time tradeoff utility values and each of the six severity ratings of patient-perceived disability in adults with strabismus. For clarity, multiple overlapping data points at 1.0 utility were replaced by single open squares with labels indicating the number of overlapping points in the original database. For utility values less than 1.0, open circles represent individual patients.