Comparison of the Rau method and the Larsen method in the evaluation of radiographic progression in early rheumatoid arthritis

Abstract

Objective: To investigate the usefulness of the radiographic scoring method proposed by Rau, et al for evaluation of joint damage in patients with early rheumatoid arthritis (RA).

Methods: Radiographs of hands and feet of 30 prospectively observed patients with early RA were assessed by the Rau method, the Larsen method, and count of erosive joints. The standardized response mean (SRM) was used to estimate the sensitivity to change of each method of assessment.

Results: Although the Rau method evaluates only the amount of bony erosion, nearly equivalent radiographic progression was observed with the Rau and the Larsen methods. Radiographic changes in the first year were sensitively identified by all 3 methods (SRM for Rau method 0.83, Larsen method 0.88, and count of erosive joints 0.84). However, in the period from 2 to 6 years after entry into the study, sensitivity to change was maintained with use of the Rau (SRM 1.38) and Larsen (SRM 0.95) methods, but not by count of erosive joints (SRM 0.49). While an apparent ceiling effect was observed after 2 years in count of erosive joints, no ceiling effects were noted for the Rau and Larsen methods.

Conclusion: Our study showed that the usefulness of the Rau method is equivalent to the Larsen method in clinical assessment of radiographic progression in early RA.