Incidence of psoriasis in children: A population-based study

Abstract

Background Although psoriasis is considered to have a “dual peak” in age of onset, currently no studies exist regarding the incidence of psoriasis in children. Objective The objective of this study is to determine the incidence of psoriasis in childhood. Methods A population-based incidence cohort of children aged <18 years first diagnosed with psoriasis between January 1, 1970 and December 31,1999 was assembled. The complete medical record of each child was reviewed and psoriasis diagnosis was validated by a confirmatory diagnosis in the medical record by a dermatologist or medical record review by a dermatologist. Age- and sex-specific incidence rates were calculated and were age- and sex-adjusted to 2000 U.S. white population. Results The overall age and sex adjusted annual incidence of pediatric psoriasis was 40.8 per 100,000 (95% confidence interval 1: 36.6, 45.1). When psoriasis diagnosis was restricted to dermatologist confirmed subjects in the medical record, the incidence was 33.2 per 100,000 (95% CI: 29.3, 37.0). Incidence of psoriasis in children increased significantly over time from 29.6 per 100,000 in 1970 to 1974 to 62.7 per 100,000 in 1995-1999 (p<0.001). Chronic plaque psoriasis was the most common type (73.7%), and the most commonly involved sites were the extremities (59.9%) and the scalp (46.8%). Limitations The population studied was a mostly Caucasian population in the upper Midwest. Conclusion The incidence of pediatric psoriasis increases with increasing age. There is no apparent “dual-peak” in incidence. The incidence of pediatric psoriasis increased in recent years in both boys and girls.