HLA-B and ankylosing spondylitis: Ankylosing spondylitis was significantly more common in HLA-B*27-positive patients (22.73%) than in those who were negative (3.57%), with a statistically significant association confirmed by a chi-square test (χ2 = 4.281, p = 0.039) and a weak but meaningful phi coefficient (φ = 0.293).