Onychocryptosis Is Associated with Low Income in a Matched Cohort Study Using the All of Us Database

Introduction: Onychocryptosis is a common and often painful nail condition, but risk factors have been relatively unexplored. We aimed to analyze associations between onychocryptosis, comorbidities, and income level. Methods: Using the National Institute of Health All of Us Research Program Database, a matched case-control study was performed for patients with onychocryptosis diagnosis and comorbidities and lifestyle factors. Results: A total of 6,246 cases of onychocryptosis and 24,984 controls were analyzed. Patients with onychocryptosis versus controls had increased risk of onychogryphosis (OR 5.66; 95% CI 4.87, 6.58), onychomycosis (2.63; 2.06, 3.36), hallux valgus (1.68; 1.50, 1.87), type 2 diabetes mellitus (1.49; 1.40, 1.60), obesity (1.38; 1.30, 1.48), and peripheral vascular disease (1.24; 1.14, 1.35) compared to controls. Patients who reported living in low-income households more often had onychocryptosis (reference group annual income >200 k; annual income <10 k USD, OR: 1.76; 95% CI: 1.46, 2.12, p < 0.001 vs. annual income 150–200 k USD, OR: 1.26; 95% CI: 0.99, 1.61, p = 0.06). Conclusion: Low income, obesity, PVD, and T2DM were associated with onychocryptosis diagnosis. It is recommended that these at-risk populations be screened for onychocryptosis and counseled on proper nail trimming techniques. Future studies are needed to examine the relationship between household income and onychocryptosis risk.