Multiple comorbidities specifically associated with keloids versus hypertrophic scars: An All of Us case control study.

Summary: Abstract Body: Keloid pathophysiology is poorly understood. Identifying keloid comorbidities may reveal mechanistic insights but is complicated by frequent co-diagnosis with hypertrophic scar. We utilized the All of Us program, containing health data from a large representative American population, to identify specific comorbidities that associate with keloids versus hypertrophic scars. Keloid and hypertrophic scar cohorts were defined by SNOMED codes. Demographic makeups were compared with chi-square test, and 568 most reported conditions were tested for associations by both univariate analysis and multivariate logistic regression. 1,397 participants with keloids only and 1,354 participants with hypertrophic scar only were identified. The cohorts differed significantly by age (p<0.0001), with the hypertrophic scar cohort having more participants age >65 (34.71% vs 23.84%), but not by race or sex at birth. Univariate analysis revealed 103 keloid-associated conditions (OR >1.5) and 50 hypertrophic scar-associated conditions (OR <0.7). Multivariate analysis, adjusting for demographic categories and all common conditions, revealed 41 keloid-associated and 32 hypertrophic scar-associated conditions (adjusted OR>2 or <0.5, p<0.05). Notably, dermatologic conditions such as acne (adj. OR=4.81, 95% CI 3.37-6.85), alopecia (adj. OR=3.58, 95% CI 1.68-7.63), and sebaceous cyst (adj. OR=2.26, 95% CI 1.43-3.56), were associated with keloids. Epidermoid cyst (adj. OR=0.23, 95% CI 0.13-0.38), truncal basal cell carcinoma (adj. OR=0.24, 95% CI 0.12-0.51), and psoriasis (adj. OR=0.47, 95% CI 0.24-0.92) were associated with hypertrophic scars. Non-dermatologic diagnoses associated with keloids included type 2 diabetes mellitus (adj. OR=2.53, 95% CI 1.23-5.18) and uterine leiomyoma (adj. OR=2.26, 95% CI 1.07-4.77). These results, identifying multiple conditions that are specifically associated with either keloid or hypertrophic scar, will help clarify pathophysiologic differences between the two conditions and may lead to more specific and efficacious therapies. Peter Luo¹, Donald A. Glass¹ 1. Dermatology, The University of Texas Southwestern Medical Center, Dallas, TX, United States. Clinical Research: Epidemiology and Observational Research