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We have developed a refined computer-based method to detect joint space narrowing (JSN) progression with the joint space narrowing progression index (JSNPI) by superimposing sequential hand radiographs. The purpose of this study is to assess the validity of a computer-based method using images obtained from multiple institutions in rheumatoid arthritis (RA) patients. Sequential hand radiographs of 42 patients (37 females and 5 males) with RA from two institutions were analyzed by a computer-based method and visual scoring systems as a standard of reference. The JSNPI above the smallest detectable difference (SDD) defined JSN progression on the joint level. The sensitivity and specificity of the computer-based method for JSN progression was calculated using the SDD and a receiver operating characteristic (ROC) curve. Out of 314 metacarpophalangeal joints, 34 joints progressed based on the SDD, while 11 joints widened. Twenty-one joints progressed in the computer-based method, 11 joints in the scoring systems, and 13 joints in both methods. Based on the SDD, we found lower sensitivity and higher specificity with 54.2 and 92.8%, respectively. At the most discriminant cutoff point according to the ROC curve, the sensitivity and specificity was 70.8 and 81.7%, respectively. The proposed computer-based method provides quantitative measurement of JSN progression using sequential hand radiographs and may be a useful tool in follow-up assessment of joint damage in RA patients.

Our computer-based method can detect the chronological change in joint space width between baseline and follow-up images as the joint space difference index (JSDI). The aim of this study was to verify the sensitivity and specificity of our computer-based method in assessment of joint space narrowing progression in rheumatoid patients. Twenty-seven patients (24 women and 3 men) with rheumatoid arthritis underwent radiography of the bilateral hand at baseline and at 1 year. The joint space narrowing (JSN) of a total of 252 metacarpophalangeal (MCP) joints and 229 carpal joints was assessed by our computer-based method, setting the Sharp/van der Heijde method as the gold standard. We constructed a receiver operating characteristic curve by using the Sharp/van der Heijde method as the gold standard and set the optimal cutoff on JSDI for MCP, carpal, and MCP/carpal joints. We then calculated the sensitivity and specificity for each cutoff in assessment of JSN progression. At the most discriminant cutoff, the sensitivity and specificity of the computer-based method for MCP joints was 78.6 versus 85.3 %, respectively (AUC = 0.837; P < 0.001). Carpal joints revealed a lower sensitivity and specificity with 64.7 and 86.8 % (AUC = 0.775; P < 0.001). Furthermore, the sensitivity and specificity for MCP/carpal joints was 71.0 versus 83.6 %, respectively (AUC = 0.778; P < 0.001). The computer-based method presented a reliable assessment of JSN progression with high sensitivity and specificity and may be useful in follow-up assessment of the joint damage in rheumatoid patients.

Objective: To investigate the validity of a computerbased method using temporal subtraction in carpal joints of patients with rheumatoid arthritis (RA), which can detect the difference in joint space between two images with the joint space difference index (JSDI). Methods: The study consisted of 43 patients with RA (39 females and 4 males) who underwent radiography at baseline and at 1-year follow-up. The joint space narrowing (JSN) of carpal joints on bilateral hand radiographs was assessed by our computer-based method, using the Sharp/ van der Heijde method as the standard of reference. We compared the JSDI of joints with JSN progression in the follow-up period with that of those without JSN progression. In addition, we examined whether there is a significant difference in JSDI in terms of laterality or topology of the joint. Results: The JSDI of joints with JSN progression was significantly higher than that of those without JSN progression (Mann-Whitney U test, p < 0.001). There was no statistically significant difference in the JSDI between the left and right carpal joints, which was analysed for five different joints altogether and each joint separately (Mann-Whitney U test, p > 0.05). There was statistically significant difference in JSDI among different joints (Kruskal-Wallis test, p = 0.003). Conclusion: These results suggest that our computerbased method may be useful to recognize the JSN progression on radiographs of rheumatoid wrists. Advances in knowledge: The computer-based temporal subtraction method can detect the JSN progression in the wrist, which is the single most commonly involved site in RA.

We retrospectively investigated the inhibitory effect on radiographic joint damage (RJD) for non-biological disease-modifying antirheumatic drug (non-bioDMARD) monotherapy or methotrexate (MTX) combination therapy for rheumatoid arthritis (RA) in the disease activity score with 28 joint counts with erythrocyte sedimentation rate (DAS28) remission.Eighty-four patients (55 cases of monotherapy, 29 cases of MTX-combination therapy) in DAS28 remission (DAS28 ≤ 2.6) were investigated from 538 RA patients newly registered between February 2007 and August 2010. The patients were analyzed for radiological assessments using the modified total Sharp score/year (mTSS/y).The remission rates and ΔmTSS/y for each agent using monotherapy were 7.1% and 0.17 for sulfasalazine; 11.9% and 0.49 for bucillamine (BUC); and 23.9% and 2.06 for MTX. Those using combination therapy were 6.8% and 1.39 for MTX + BUC; 23.5% and -1.64 for MTX + leflunomide; and 8.0% and 0.31 for MTX + tacrolimus. The cumulative distribution in the single and combination therapy groups showed improvement of percentages in structural remission from baseline to 1-year treatment, 34.1% to 60.9% (P0.05) and from 0% to 56.7%(P0.0001), respectively. Baseline mTSS (r = 0.67, P0.0001), disease duration (r = 0.40, P0.01), swollen joint counts (r = 0.33, P0.05), and anti-cyclic citrullinated peptide antibody (r = 0.31, P0.05) were useful predictors of RJD for non-bioDMARD monotherapy, but not for combination therapy.Satisfactory inhibition of RJD was observed in the DAS28 remission cases of monotherapy or MTX combination therapy with a non-bioDMARD.