BACKGROUND AND OBJECTIVES: In @entity309 , joint radiography is still the most frequently used instrument to assess the progression of @entity16 . Unfortunately, the poor quality of the radiographic scoring methods available has a negative impact on the power in clinical trials. This study focuses on the influence of the following 4 factors on radiographic scores according to van der Heijde's modification of the @entity3834 method: intraobserver variation, interobserver variation, follow-up time, and number of measurement occasions within a @entity1 series. METHODS: One hundred and seventy-two @entity1 in the early stages of @entity309 were followed up. During the first 3 years, radiographs of the hands and feet were taken twice yearly and scored by 3 observers. The scoring process was repeated after an additional 3-year period. Correlation coefficients and differences between observers were calculated to define variability. The influence of the 4 factors on variability was studied. RESULTS: One observer assigned a significantly higher score than the other 2, who had been trained together. Interobserver variability decreased as follow-up time increased. Interobserver correlation coefficients became higher, with smaller differences between observers for progression scores than for absolute scores. Increasing the number of measurements within a @entity1 series led to higher scores. Intraobserver correlation coefficients were high, and a training effect occurred when the time between measurements was 1 year, resulting in lower scores. CONCLUSIONS: This study demonstrates that, and shows how, the investigated factors influence the variability of the modified @entity3834 method. It is extremely important to take interobserver variation into account when designing protocols for multicenter clinical trials. A progression scoring method is recommended for studies assessing radiographic damage or clinical trials.

Modified XXXX method: factors influencing reproducibility and variability.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity16 :: ('MESH:D009422', 'Disease') :: ['joint damage'] @entity309 :: ('MESH:D001172', 'Disease') :: ['rheumatoid arthritis'] @entity3834 :: ('23013', 'Gene') :: ['Sharp']
@entity3834 :: (23013,Gene) :: ['sharp']
