Toenail Onychomycosis with or without Diabetes in Canada: Patient Treatment Preferences and Health State Utilities

Abstract

Background: Toenail onychomycosis affects approximately 6.7% of Canadians. Symptoms include nail discolouration/disfiguration and pain; psychosocial impacts contribute to reduced health-related quality-of-life. Comorbid diabetes increases the risk of complica-tions and exacerbates burden. Treatment may include topical therapy and/or oral agents. Purpose: To understand toenail onychomycosis treatment preferences, and to quantify the impact of toenail onychomycosis, with or without diabetes, on patient well-being. Methods: Adults living in Canada with self-reported, physician-diagnosed, toenail onychomycosis were recruited online. A discrete choice experiment was used to quantify treatment preferences. Scenarios were randomized; data were analyzed using conditional logit regression. Health state utilities were estimated using the Health Utilities Index Mark 3® . Results were stratified by diabetes status and toenail onychomycosis severity; the Wilcoxon Rank Sum test was used to assess between-group utility differences. Results: Three-hundred thirteen participants with toenail onychomycosis were included (161 had comorbid diabetes; 61.3%, severe onychomycosis). The mean age was 57.7 years; 55.9% were male. Treatment attributes with statistically significant impacts on patient preferences were efficacy (odds ratio [OR],1.04; 95% confidence interval [CI], 1.02–1.05 per 1% increased treatment success), administration method (one pill versus topical nail lacquer reference, 1.14; 1.04–1.26; topical solution applicator versus reference: 1.15; 1.03–1.29), severe adverse events (0.85; 0.80–0.90 per 1% increased risk), and risk of potential pharmacodynamic (0.80; 0.76– 0.85) and alcohol (0.93; 0.88–0.98) interactions; preferences were more pronounced for efficacy and avoiding severe adverse events among toenail onychomycosis patients with comorbid diabetes. The mean (95% CI) utility value was 0.73 (0.70–0.75) overall, and statistically significantly lower (p=0.02) for toenail onychomycosis patients with diabetes (0.70; CI, 0.66–0.73) than those without (0.76; CI, 0.72–0.79). Conclusion: Among patients with toenail onychomycosis, the presence of diabetes was associated with differing treatment-related preferences. Utility values for patients with toenail onychomycosis represent a significant decline from full health that is exacerbated by comorbid diabetes.