Analyzing Gender Disparities in Ankylosing Spondylitis: Exploring the Factors Behind Severe Sacroiliac Joint Disease Without Spinal Involvement.

We have read with interest the paper by Ridley et al 1 on the radiographic damage discordance between the sacroiliac joints (SIJs) and the spine in patients with ankylosing spondylitis (AS) from the Prospective Study of Outcomes in AS (PSOAS) cohort, which includes patients from the United States and Australia. Their results have encouraged us to investigate the prevalence of severe SIJ disease without evidence of concomitant syndesmophytes in the spine in our patient cohort from Spain.