The aim of this case-control study was to identify risk factors associated with necrotizing fasciitis (NF) of the lower limbs.

We conducted a prospective case-control study in hospital dermatology departments in 5 sub-Saharan African countries over a 2-year period (April 2017 to July 2019). The cases were patients with NF of the lower limbs and the controls were patients with leg erysipelas. Each case was matched with two controls for age (±5 years) and sex. We analyzed local and general factors.

During the study period, 159 cases (73 females, 86 males) were matched with 318 controls. The mean age was 48.5±15.8 years for cases and 46.5±16.2 years for controls (P=0.24). The main local signs of NF were cutaneous necrosis (83.7%), pain (75.5%) and induration (42.1%). Multivariate analysis showed the following to be independent risk factors associated with NF of the lower limbs: obesity (odds ratio [OR]=2.10; 95% confidence interval [CI]: 1.21–3.42), diabetes (OR=3.97; 95% CI: 1.95–6.13), nicotine addiction (OR=5.07; 95% CI: 2.20–11.70), use of non-steroidal anti-inflammatory drugs (NSAIDs) (OR=7.85; 95% CI 4.60–14.21) and voluntary cosmetic depigmentation (OR=2.29; 95% CI: 1.19–3.73).

Our study documents the role of NSAID use at the onset of symptoms as a risk factor for NF of the lower limbs. However, the originality of our study consists in the identification of voluntary cosmetic depigmentation as a risk factor for NF of the lower limbs in sub-Saharan Africa patients. Our results also identified typical overarching factors such as diabetes, obesity and nicotine addiction. Knowing these factors and taking them into account will enable optimization of management strategies for these conditions.