Abstract: Objective To verify whether there is any difference between early-onset and late onset subtypes of psoriasis and the rationality of this classification. Methods A total of 1 632 patients with psoriasis vulgaris were included in this study. The distribution of age at onset was calculated. The disease severity at first visit and follow up, and the family history were assessed according to different ages at onset. The results were evaluated in the light of the data from a national psoriasis survey in 1984. Results There was only one peak regarding to the age at onset in psoriasis vulgaris, rather than two peaks according to our study, it was consistent with the results of the national large scale survey reported in 1984. It was found that the earlier the age at onset, the more frequently the patient had positive family history. There was some relationship between the disease severity and the age at onset, however, a clear cut age at onset by which the disease serverity could be determined was not identified in this study. Conclusion It is suggested that the early age at onset be related only to the increased possibility of family history. Its value in clinical management is not significant.

Key words: Psoriasis, Age at onset