Epidemiology of nummular eczema - methodological approaches and outcomes from nationwide claims data analyses

Nummular eczema (NE) is a chronic skin condition with limited epidemiologic data. This study estimates its prevalence, incidence and severity in Germany.

A cross-sectional analysis (2016-2022) used German insurance claims data to identify NE cases (ICD-10 L30.0) and assess severity (hospitalization, work disability, systemic treatment) and comorbid skin conditions, including atopic dermatitis (AD).

In 2022, the prevalence of NE ranged from 0.07% to 0.26%. The incidence was 0.16%-0.17%. The mean age was 47.5 years, and 57.4% of the patients were male. Older males had a higher prevalence, while children younger than six years (0.34%), especially those younger than 2 years (0.56%-0.57%), were more affected. Severe NE was found in 14.8% of the patients. AD co-occurred in 18% of NE cases. NE patients had an increased risk of lichen simplex chronicus (RR 9.71), irritant contact dermatitis (RR 9.60), pruritus (RR 5.71), allergic rhinitis (RR 1.78), and allergic asthma (RR 1.49).

Despite differences in methodological approaches leading to some variation, the prevalence of NE in the German population can be reasonably estimated at approximately 0.26%. Overlaps and miscoding may have occurred, particularly with other forms of eczema, underscoring the need for reliable diagnostics and standardized coding.