Itch: A Global Problem?

The Global Burden of Disease (GBD) Study 2010 estimated the GBD attributable to 15 categories of skin disease from 1990 to 2010 for 187 countries. For each of the following diseases, we performed systematic literature reviews and analyzed resulting data: eczema, psoriasis, acne vulgaris, pruritus, alopecia areata, decubitus ulcer, urticaria, scabies, fungal skin diseases, impetigo, abscess, and other bacterial skin diseases, cellulitis, viral warts, molluscum contagiosum, and non-melanoma skin cancer. We used disability estimates to determine nonfatal burden. Three skin conditions, fungal skin diseases, other skin and subcutaneous diseases, and acne were in the top 10 most prevalent diseases worldwide in 2010, and eight fell into the top 50; these additional five skin problems were pruritus, eczema, impetigo, scabies, and molluscum contagiosum. Collectively, skin conditions ranged from the 2nd to 11th leading cause of years lived with disability at the country level. At the global level, skin conditions were the fourth leading cause of nonfatal disease burden. Using more data than has been used previously, the burden due to these diseases is enormous in both high- and low-income countries. These results argue strongly to include skin disease prevention and treatment in future global health strategies as a matter of urgency.

Chronic itch is a common and distressing symptom that arises from a variety of skin conditions and systemic diseases. Despite this, there is no clinically based classification of pruritic diseases to assist in the diagnosis and cost-effective medical care of patients with pruritus. The proposed classification focuses on clinical signs and distinguishes between diseases with and without primary or secondary skin lesions. Three groups of conditions are proposed: pruritus on diseased (inflamed) skin (group I), pruritus on non-diseased (non-inflamed) skin (group II), and pruritus presenting with severe chronic secondary scratch lesions, such as prurigo nodularis (group III). The next part classifies the underlying diseases according to different categories: dermatological diseases, systemic diseases including diseases of pregnancy and drug-induced pruritus, neurological and psychiatric diseases. In some patients more than one cause may account for pruritus (category "mixed") while in others no underlying disease can be identified (category "others"). This is the first version of a clinical classification worked out by the members of the International Forum for the Study of Itch. It is intended to serve as a diagnostic route for better evaluation of patients with chronic pruritus and aims to improve patients' care.