Incidence and prevalence of prurigo nodularis and associated comorbidities in Denmark from 1998 to 2021

Prurigo nodularis (PN) is a chronic skin condition characterized by intense itching from nodular skin lesions. Despite its impact on patients' quality of life, limited data exist on its epidemiology.

To estimate the incidence and prevalence of hospital-diagnosed PN and to explore the burden of associated comorbidities.

A national register-based study in Denmark was conducted using data from Danish national health registers to determine the incidence and prevalence of PN diagnosed in hospitals from 1998 to 2021 and to explore the occurrence of comorbidities.

In total, we identified 1209 individuals diagnosed with PN. The mean age of onset was 45 years, with a female predominance of 58% (696/1209). The prevalence of PN increased over the studied period, reaching 14.1 per 100 000 individuals by 2021. Comorbidities such as chronic kidney disease had higher odds ratios preceding the diagnosis of PN, whereas the odds ratios for atopic dermatitis, mood disorders and depressive disorders increased following the onset of PN.

The findings indicate a significant association between PN and various comorbidities, emphasizing the need for multidisciplinary care. The increase in prevalence suggests a growing burden of disease. Although the study may underestimate the true prevalence of PN because of reliance on hospital records, it reveals a rising rate prevalence of PN and associated comorbidities in Denmark. The observed high prevalence of mental health problems in individuals with PN should be a focus of concern for the treating physicians.