Associations of amino acids at HLA–DRB1, HLA–B, and HLA–DPB1 that are known to predispose to rheumatoid arthritis (RA) development with radiographic progression in RA. The yearly radiographic progression rates per risk amino acid in each individual cohort are shown. P values are from the fixed-effects meta-analyses evaluating the 4 cohorts, which consisted of a total of 1,878 patients and 4,911 sets of radiographs. Risk amino acids were defined according to the findings of Raychaudhuri et al (10). For the DRB1 shared epitope (SE), I2 = 22.9%, P = 0.27, fixed-effects P = 6.41 × 10−7, and random-effects P = 2.01 × 10−4. For Val/Leu at DRB1 position 11, I2 = 23.0%, P = 0.27, fixed-effects P = 5.11 × 10−7, and random-effects P = 2.19 × 10−4. For Val/Leu at DRB1 position 11 adjusted for SE status, I2 = 37.3%, P = 0.19, fixed-effects P = 0.022, and random-effects P = 0.066. For Asp at B position 9, I2 = 0.0%, P = 0.59, fixed-effects P = 0.43, and random-effects P = 0.43. For Phe at DPB1 position 9, I2 = 0.0%, P = 0.85, fixed-effects P = 0.024, and random-effects P = 0.024. For Phe at DPB1 position 9 adjusted for SE status, I2 = 0.0%, P = 0.90, fixed-effects P = 0.093, and random-effects P = 0.093. EAC = Early Arthritis Clinic; HCSC-RAC = Hospital Clinico San Carlos–Rheumatoid Arthritis Cohort; NDB = National Data Bank for Rheumatic Diseases; ES = effect size; 95% CI = 95% confidence interval.