Clinical patterns and characteristics of ankylosing spondylitis in China

The study aimed to determine whether unique clinical patterns of AS may exist in China, specifically to explore the different clinical manifestations caused by gender, HLA-B27 status, and age at disease onset. The multicenter cross-sectional survey was conducted and 1251 patients were enrolled across China, representing a broad spectrum of Chinese AS patients. The mean age at onset and diagnosis were 29.2 (11.4) and 33.5 (12.6) years, respectively. The male/female ratio was 2.7:1. Acute anterior uveitis (AAU) was experienced in 10.3% of AS patients and 9.1% patients had juvenile-onset AS (JoAS). Men were significantly younger at onset and diagnosis and showed a higher frequency of HLA-B27 positivity, JoAS, and AAU than women. HLA-B27-positive patients had a younger age of onset than HLA-B27-negative patients. HLA-B27-positive patients were nearly three times as likely to develop AAU than negative patients (P = 0.04). JoAS patients had a family history of AS more often than adult-onset AS (AoAS) patients, and 4.9% of JoAS patients underwent surgical treatments, a rate more than six times that of AoAS patients (P = 0.01). Men had higher levels of C-reactive protein than women, as did HLA-B27 positives compared to negative patients, and JoAS compared to AoAS (all P < 0.05). The clinical patterns of our AS patients were similar to those in other studies in non-Chinese cohort: (1) the age at onset was 29.2 (11.4) years, which was older than found in other studies; (2) men were more likely be HLA-B27 carriers than women; and (3) AAU was less common in Chinese patients.