Multiple computer-based methods of measuring joint space width can discriminate between treatment arms in the COBRA trial -- Update of an ongoing OMERACT project.

Previously reported data on 5 computer-based programs for measurement of joint space width focusing on discriminating ability and reproducibility are updated, showing new data. Four of 5 different programs for measuring joint space width were more discriminating than observer scoring for change in narrowing in the 12 months interval. Three of 4 programs were more discriminating than observer scoring for the 0-18 month interval. The program that failed to discriminate in the 0-12 month interval was not the same program that failed in the 0-18 month interval. The committee agreed at an interim meeting in November 2007 that an important goal for computer-based measurement programs is a 90% success rate in making measurements of joint pairs in followup studies. This means that the same joint must be measured in images of both timepoints in order to assess change over time in serial radiographs. None of the programs met this 90% threshold, but 3 programs achieved 85%-90% success rate. Intraclass correlation coefficients for assessing change in joint space width in individual joints were 0.98 or 0.99 for 4 programs. The smallest detectable change was < 0.2 mm for 4 of the 5 programs, representing 29%-36% of the change within the 99th percentile of measurements.

Automated measurement of joint space width in small joints of patients with rheumatoid arthritis.

OBJECTIVE: Comparison of performances of 5 (semi)automated methods in measuring joint space width (JSW) in rheumatoid arthritis. METHODS: Change in JSW was determined by 5 measurement methods on 4 radiographs per patient from 107 patients included in the COBRA trial (comparing sulfasalazine alone or in combination with methotrexate and corticosteroids). For each method the number of patients with sufficient available results was assessed (efficiency). An independent repeated measurement was carried out on a random sample of 30 patients' baseline and 1-year radiographs, to evaluate within-method reliability of change scores. Discriminatory ability (DA) of the measurement methods (between the 2 treatment arms) was compared with the DA of the Sharp-van der Heijde score (SHS) and its 2 components (erosion and JSW scores). RESULTS: The overall success rate varied widely between methods. Applying the chosen threshold of a minimum of 50% available joints with a change score per patient resulted in a success rate > 92% in 4/5 methods. Repeatability of measurements was good for most methods (intraclass correlation coefficient > or = 0.80 in 4/5 methods). Almost all measurement methods in 3 followup periods (12/14) showed a lower mean loss of JSW in patients from the intensive treatment group, although this was rarely statistically significant, confirming the known difference in structural damage. JSW as measured by the (semi)automated systems often showed higher DA than the JSW score of the SHS, but was lower than the total SHS and erosion scores. CONCLUSION: Although efficiency of the methods should be improved further, results already show good reliability and encouraging DA of most methods. Optimal information may be obtained with a combination of scoring of erosions and (semi)automated measurement of JSW.

Computer based methods for measurement of joint space width: update of an ongoing OMERACT project.

Computer-based methods of measuring joint space width (JSW) could potentially have advantages over scoring joint space narrowing, with regard to increased standardization, sensitivity, and reproducibility. In an early exercise, 4 different methods showed good agreement on measured change in JSW over time in the small joints of the hands and feet. Despite differences in measurement values between methods, measurement of within-joint change over time showed no systematic differences. The within-method variation was small, with intra-operator variation being smaller than inter-operator variation. Although this initial study was limited in terms of the number of patients and timepoints (total 10), the number of joints was relatively high (340 joints), so the results were considered strong evidence supporting the validity of computer-based JSW measurements to continue the study of the potential value of JSW by comparison of measurements to manual scoring of joint space narrowing using the COBRA trial images.