[Risk factors associated with acne keloidalis nuchae, in black subjects: A case-control study].

Objective. - The aim of this case-control study was to identify risk factors associated with acne keloidalis nuchae (AKN), seen in a dermatology clinic in Lome (Togo). Patients and methods. - This was a case-control study conducted from January to December 2018. Patients were recruited at outpatients dermatological clinics and controls were recruited at outpatients dermatological clinics and then in other hospital departments. Results. - We recruited 303 consenting subjects, comprising 101 patients with AKN and 202 controls case-matched by age (+/- 5 years). The mean patient age was 34.9 +/- 10.7 years vs. 35.6 +/- 11.2 years for controls. The most frequently observed AKN lesions were papules (73/101; 72.2%), fibrous scars (42/101; 41.5%) and folliculitis/pustules (41/101; 40.6%). In multivariate analysis, the following factors were associated with AKN: excess weight (adjusted odds ratio= 4.8; 95% CI = [2.3-11.7]) or obesity (OR = 9.2; 95% CI = [2.1-34.2]), bleeding during hairdressing either occasionally (aOR = 13.9; 95% CI = [5.1-40.0]) or systematically (aOR = 22.1; 95% CI = [6.2-40.1), hairdressing procedures less than once per week (aOR = 10.1; 95% CI = [3.2-50.8]), and extremely close cropping of hair (aOR =4.9; 95% CI = [2.8-15.5]). Conclusion. - AKN is common in young adults. Excess weight or obesity, bleeding during hairdressing, and frequency and style of hairdressing are all associated factors. The results of this study stress the importance of limiting injury during hairdressing, and of refraining from shaving or cropping hair without a trimmer. Since management of AKN is extremely difficult, identification of associated risk factors allows suitable preventive approaches to be adopted. (C) 2020 Elsevier Masson SAS. All rights reserved.