Scoring with the Berlin MRI method for assessment of spinal inflammatory activity in patients with ankylosing spondylitis: a calibration exercise among rheumatologists.

ABSTRACT

OBJECTIVES: To test the reliability of the Berlin MRI scoring method and the effect of a calibration exercise on the score's reliability among untrained readers in MRI examinations of patients with established ankylosing spondylitis (AS). METHODS: Eleven rheumatologists read blinded images of 20 AS patients before and after a two-day workshop on the Berlin MRI scoring method. Reliability (intra- and inter-reader) and concordance with the expert (all measured by intraclass correlation coefficient (ICC)) were compared before and after 2 weeks of the training. Feasibility in terms of time and difficulty was also measured. RESULTS: The mean Berlin score increased from (mean ± standard deviation) 5.04 ± 6.41 before to 6.40±7.08 after the calibration exercise (p<0.01). Inter-reader ICC decreased from 0.83 (95% CI 0.75-0.93) to 0.78 (95% CI 0.66-0.90), and intra-reader ICC from 0.89 (95% CI 0.84-0.94) to 0.87 (95% CI 0.82-0.92). Agreement with an experienced reader improved after the calibration exercise, with ICC = 0.59 (95% CI 0.45-0.76) before vs. ICC = 0.65 (95% CI 0.50-0.80) after training. CONCLUSIONS: The Berlin method is a reliable scoring method for assessment of spinal inflammatory activity by using MRI in patients with AS, even in the hands of inexperienced readers. A calibration exercise can improve feasibility and sensitivity of the scoring method.