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

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.