Implementation of Z-Scores as an Age- and Sex-independent Parameter for Estimating Joint Space Widths in Rheumatoid Arthritis

The relationship between structural analysis of the hand and clinical characteristics in psoriatic arthritis

Up to now, there is only limited information available on a possible relationship between clinical characteristics and the mineralization of metacarpal bones and finger joint space distance (JSD) in patients with psoriatic arthritis (PsA). Computerized digital imaging techniques like digital X-ray radiogrammetry (DXR) and computer-aided joint space analysis (CAJSA) have significantly improved the structural analysis of hand radiographs and facilitate the recognition of radiographic damage. The objective of this study was to evaluate clinical features which potentially influence periarticular mineralization of the metacarpal bones and finger JSD in PsA-patients. 201 patients with PsA underwent computerized measurements of the metacarpal bone mineral density (BMD) with DXR and JSD of all finger joints by CAJSA. DXR-BMD and JSD were compared with clinical features such as age and sex, disease duration, C-reactive protein (CRP) as well as treatment with prednisone and disease-modifying antirheumatic drugs (DMARDs). A longer disease duration and an elevated CRP value were associated with a significant reduction of DXR-BMD, whereas JSD-parameters were not affected by both parameters. DXR-BMD was significantly reduced in the prednisone group (-0.0383 g/cm²), but prednisone showed no impact on finger JSD. Patients under the treatment with bDMARDs presented significant lower DXR-BMD (-0.380 g/cm²), JSD_MCP (-0.0179 cm), and JSD_PIP (-0.0121 cm) values. Metacarpal BMD was influenced by inflammatory activity, prednisone use, and DMARDs. In contrast, finger JSD showed only a change compared to baseline therapy. Therefore, metacarpal BMD as well as finger JSD represent radiographic destruction under different aspects.

Sind röntgenologische Scoring-Methoden als Parameter zur Verlaufsbeurteilung der rheumatoiden Arthritis noch zeitgemäß?

Die radiologische Progression beschreibt das Ausmaß der Gelenkzerstörung im Verlauf einer rheumatoiden Arthritis. Zur Quantifizierung der radiologischen Progression werden Scoring-Methoden (z. B. van der Heijde Modifikation des Sharp-Score) eingesetzt. In verschiedenen Studien zu biologischen- bzw. target-synthetischen Disease Modifying Anti-Rheumatic Drugs gelang nur unzureichend eine Differenzierung der radiologischen Progression. Zudem finden die Scores oft keinen routinemäßigen Einsatz in der klinischen Entscheidungsfindung. Durch die computerbasierte Analyse von Handröntgenaufnahmen ist eine valide Quantifizierung der radiologischen Progression und die zuverlässige Bewertung von Therapieeffekten möglich. Somit stellen die computerbasierten Methoden eine vielversprechende Alternative in der Quantifizierung der radiologischen Progression dar.

Radiographic remission in rheumatoid arthritis quantified by computer-aided joint space analysis (CASJA): a post hoc analysis of the RAPID 1 trial

Background

The reduction of finger joint space width (JSW) in patients with rheumatoid arthritis (RA) is strongly associated with joint destruction. Treatment with certolizumab pegol (CZP), a PEGylated anti-TNF, has been proven to be effective in RA patients. The computer-aided joint space analysis (CAJSA) provides the semiautomated measurement of joint space width at the metacarpal-phalangeal joints (MCP) based on hand radiographs. The aim of this post hoc analysis of the RAPID 1 trial was to quantify MCP joint space distance (JSD-MCP) measured by CAJSA between baseline and week 52 in RA patients treated with certolizumab pegol (CZP) plus methotrexate (MTX) compared with MTX/placebo.

Methods

Three hundred twenty-eight patients were included in the post hoc analysis and received placebo plus MTX, CZP 200 mg plus MTX and CZP 400 mg plus MTX. All patients underwent X-rays of the hand at baseline and week 52 as well as assessment of finger joint space narrowing of the MCP using CAJSA (Version 1.3.6; Sectra; Sweden). The joint space width (JSW) was expressed as mean joint space distance of the MCP joints I to V (JSD-MCP_total).

Results

The MTX group showed a significant reduction of joint space of − 4.8% (JSD-MCP_total), whereas in patients treated with CZP 200 mg/MTX and CZP 400 mg/MTX a non-significant change (JSD-MCP_total + 0.6%) was observed. Over 52 weeks, participants with DAS28 remission (DAS28 ≤ 2.6) exhibited a significant joint space increase of + 3.3% (CZP 200 mg plus MTX) and + 3.9% (CZP pegol 400 mg plus MTX).

Conclusion

CZP plus MTX did not reduce JSD-MCP_total estimated by CAJSA compared with MTX/placebo. Furthermore, clinical remission (DAS28 ≤ 2.6) in patients treated with CZP plus MTX was associated with an increasing JSD, indicating radiographic remission in RA.

Joint damage in rheumatoid arthritis: assessment of a new scoring method

INTRODUCTION

The aim of this study was to assess a novel approach for the quantification of finger joint space narrowing and joint destruction in patients with rheumatoid arthritis (RA) focusing on the peripheral hand articulations.

METHODS

A total of 280 patients with verified RA underwent computerized semi-automated measurements of joint space distance at the finger articulations based on radiographs. The Z-Score, which can differentiate between joint space alterations caused by RA versus age/gender-related changes, was calculated as a comparative parameter. The severity of joint space narrowing was also quantified by the Sharp Score. 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. Additionally, the potential of the Z-Score regarding the differentiation of therapeutic effects on joint space widths in patients under a therapy of methotrexate versus leflunomide was performed.

RESULTS

The Z-Scores of finger articulations in patients with RA were generally decreased. Metacarpal-phalangeal (MCP) joint articulations showed a continuous significant decline of -1.65±0.30 standard deviations dependent on the Sharp Score. The proximal-interphalangeal joints also revealed a significant reduction of the Z-Score (-0.96±0.31 standard deviations). The sensitivity and specificity of MCP joint space distance for the detection of erosions were 85.4% versus 55.2%. 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.

CONCLUSION

The Z-Scoring method based on computer-aided analysis of joint space widths was able to reliably quantify severity-dependent joint space narrowing in RA patients. In the future, calculation of a Z-Score based on gender-specific and age-specific reference data shows the potential for a surrogate marker of RA progression that comprehends the early identification of patients with RA, and in particular those with erosive course of the disease, enabling a timely therapeutic strategy for cartilage protection.

The usefulness of computer-aided joint space analysis in the assessment of rheumatoid arthritis

OBJECTIVE

Computer-aided joint space analysis (CAJSA) is a newly developed technique for the measurement of radiogeometrically detectable joint space widths of the metacarpal-phalangeal (JSD-MCP) and proximal-interphalangeal articulations (JSD-PIP). The aim of this study was to verify the sensitivity and specificity of these CAJSA measurements in the assessment of established RA.

METHODS

Four hundred and fifty-eight participants (248 healthy subjects, 210 RA patients) underwent computerized semi-automated measurements of the JSD-MCP and JSD-PIP articulations (CAJSA, Radiogrammetry Kit, Version 1.3.6) based on digitally performed radiographs. The Sharp joint space narrowing score was also performed to determine RA-related joint space narrowing.

RESULTS

The significant severity-dependent reduction for JSD-MCP was -44.0% and for JSD-PIP, -25.94% between Sharp scores 0 and 3. The sensitivity and specificity of JSD-MCP (total) was 88.1% versus 77.8%, respectively (AUC = 0.920; P < 0.001). Furthermore, JSD-PIP (total) revealed a lower sensitivity and specificity with 61.4% and 88.7% (AUC = 0.878; P < 0.001).

CONCLUSION

The CAJSA method presented a reliable assessment of disease-related joint space narrowing in patients suffering from RA with excellent sensitivity and specificity. By providing quantitative data, other scoring methods could be significantly improved, and thereby the accuracy of the diagnosis and a better therapeutic evaluation could be achieved.

Reproducibility and influence of hand rotation on computer-aided joint space analysis

OBJECTIVES

Computer-aided joint space analysis (CAJSA) is a recently developed, semi-automated tool to aid in the measurement of joint space margins based on hand radiographs. The objective of this study is to verify the potential effect of hand rotation during X-ray imaging on the measurement of joint space width using CAJSA and to evaluate the reproducibility of the CAJSA technique in healthy subjects and in patients with rheumatoid arthritis.

METHODS

All joint space distance (JSD) measurements were performed using CAJSA-technology at the metacarpophalangeal articulation based on conventional and digital hand radiographs.

RESULTS

I. Hand rotation showed an effect on the reproducibility with CV ranging between 0.39% (angulation 1°) and 1.66% (angulation 19°). II. Regarding the overall reproducibility of the CAJSA method, the intra-radiograph reproducibility of JSD was calculated with CV=0.54% for conventional images and CV=0.38% for digital images. The inter-radiograph reproducibility error was observed with CV=0.66% (conventional images) and CV=0.63% (digital images). III. The study revealed a reproducibility for CAJSA measurements in RA ranging between 0.37% (JSD-MCP ring finger; van der Heijde-modification of the Sharp method score 1) to 1.37% (JSD-MCP index finger; van der Heijde-modification of the Sharp method score 3).

CONCLUSION

CAJSA measures JSD at the metacarpophalangeal articulation with high reproducibility in healthy subjects and in patients with differing stages of rheumatoid arthritis. Additional findings show that hand rotation during X-ray imaging has an impact on the CAJSA measurements; thus avoiding acquisition of hand radiographs with a rotation error of more than 15 degrees can be recommended.

Feasibility study of semi-automated measurements of finger joint space widths

The purpose of this study is to evaluate technical feasibility based on image capturing conditions (film-focus distance (FFD), film sensitivity, film brand, exposure level and tube voltage) that potentially alter radiographs and consequently may influence the semi-automated measurement of joint space distance (JSD) by computer-aided joint space analysis (CAJSA) in rheumatoid arthritis and osteoarthritis. The radiographs of a left hand (deceased man) were acquired under systematically changing image capturing conditions (exposure level: 4-8 mAs; FFD: 90-130 cm; film sensitivity: 200/400 and tube voltage: 40-52 kV with different image modalities: conventional radiographs, original digital radiographs, digital print-outs). All JSD-measurements were performed with the CAJSA-technology (Radiogrammetry Kit, Version 1.3.6; Sectra; Sweden) at the metacarpal-phalangeal articulation. JSD-analysis was not influenced by changes of FFD, exposure level, film sensitivity or film brand. JSD showed significant variation caused by tube voltage (conventional: CV = 1.913% for Agfa and CV = 2.448% for Kodak; digital: CV = 0.741% for Philips print-outs and CV = 0.620% with original digital images versus CV = 2.185% for Siemens print-outs and 0.951% with original digital images). Computer-aided joint space analysis for JSD-measurements is unaffected by the following image capturing parameters: film-focus distance, film sensitivity, film brand and exposure level. An influence of tube voltage was detected in a lesser extent for original digital images compared to the printed digital as well as conventional versions. Consequently, a standardized tube voltage is essential for accurate reproductions of CAJSA-measurements in rheumatoid arthritis and osteoarthritis.