Fig. 1.

Cumulative distribution of the age at onset of axial symptoms, stratified by HLA-B27 status

(A) All included axSpA patients, (B) Asia, (C) Europe and North America, (D) Latin America and (E) Middle East and North Africa. The black lines represent all patients in each region, the blue lines represent HLA-B27-positive patients and the red lines represent HLA-B27-negative patients. The horizontal dashed line represents the 95% point and the vertical dashed line represents an age at onset of 45 years.