All five Z scores were added and subsequently divided by 5, generating a joint Z score with positive and negative scores indicating values higher and lower, respectively, than the mean risk profile for this specific population.
To quantify age-independent and gender-independent joint space narrowing, the Z-Score of the CAJSA measurements was used [ 9].
No association was found between joint hypermobility and height Z-score (rpb = 0.113, p = 0.45, n = 47).
Association between joint hypermobility and height Z-score was computed with point-biserial correlation coefficient (SPSS software version 19; SPSS Inc., Chicago, IL, USA).
Using the Sharp Score for joint space narrowing, the Z-Score of the MCP articulations confirmed an accentuated reduction from score 2 (-0.39 ± 0.57 SDs) to score 3 (-1.83 ± 1.28 SDs) [ 9].
This study presents the severity-dependent reduction of joint space widths using the Z-Score based on CAJSA estimates in patients with RA, in particular the MCP JSD of the second and third fingers as a surrogate marker of RA progression.
Our data demonstrated a continuously significant joint space narrowing as measured by the Z-Score using the Sharp Score for joint space narrowing for assessment of RA severity.
The Sharp Score for joint space narrowing was not able to detect different treatments, whereas an accentuated stabilization of joint space narrowing could be identified for the Z-Score of the MCP joints in patients treated with leflunomide and methotrexate.
An accentuated stabilization of joint space narrowing could be identified for the Z-Score of the MCP joints in both subgroups treated with leflunomide and methotrexate, and the Z-Score was able to quantify therapeutic effects in a longitudinal study design.
Sensitivity and specificity of the Z-Score (based on joint space widths differentiated for each peripheral finger joint) were evaluated to reveal the potential for the occurrence of erosions.
Regarding the DIP joints, a nonsignificant correlation was observed between the Z-Score and the Sharp Score for joint space narrowing.
