RESEARCH - The use of digital x-ray radiogrammetry in the assessment of joint damage in RA

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Ann Rheum Dis. 2005 Aug 26; [Epub ahead of print]

The use of Digital X-Ray Radiogrammetry in the assessment of Joint Damage in

Rheumatoid Arthritis.

Jawaid WB, Crosbie D, Shotton J, Reid DM, A.

University of Aberdeen, United Kingdom.

OBJECTIVE: To examine cross-sectionally the ability of digital x-ray

radiogrammetry (DXR) to assess bone loss in RA compared with a manual

radiograph scoring technique and the relationship of both these scores with

other disease indices. METHODS: Consecutive consenting subjects attending

the RA clinic were enrolled. SUBJECTS: were sent for x-ray; had their

demographic details recorded; completed a self assessment questionnaire,

which collected data on early morning stiffness, pain, patient global

assessment and included a modified health assessment questionnaire (HAQ);

had blood taken for erythrocyte sedimentation rate measurement and were

assessed by author JC, a trained nurse, who recorded an assessor's global

assessment (AGA) and 28 point tender and swollen joint counts. All x-ray

films were scored manually using the modified Sharp scoring technique by a

single observer and 20 films were randomly selected for rescoring by 3

readers. All films were assessed using the Pronosco X-Posure System version

2.0. Analysis was performed in 225 subjects and included chi-squared tests,

independent t-tests, multiple linear regression and partial correlations as

appropriate. The precision of scoring techniques was estimated by

calculating the smallest detectable difference (SDD), the coefficient of

variation (CV) and the coefficient of repeatability (CR) from Bland & Altman

plots. RESULTS: The precision of DXR depending on the index assessed varied

from SDD: 0.002 to 0.9; CV: 0.09% to 5.9%; CR: 0.002 to 0.792.These figures

were better than that of the intra and inter-observer Sharp scores SDD =

73.9; CV = 27.8%; CR: 33.0 to 47.6). The DXR measurements that significantly

predict Sharp scores are bone mineral density (BMD, R(2) = 0.210),

metacarpal index (MCI, R(2) = 0.222) and cortical thickness (CT, R(2) =

0.215). The other DXR measurements, the derived porosity index and bone

width, did not correlate to any aspect of the modified Sharp score. In

females, DXR measurements significantly correlated with the modified HAQ

scores but not with any of the other disease indices. In contrast, Sharp

scores significantly correlate with AGA, swollen and tender joint counts,

pain, HAQ and DAS28.

CONCLUSION: In our study DXR measurements are much more precise than Sharp

scores, but just like the latter are related to long-term disease activity

in RA. DXR is simple to use, does not require intensive training and if used

in a clinical setting may have the ability to quickly and cheaply identify

subjects not responding to standard therapy or may allow selection of

subjects who would benefit from more aggressive therapy with newer, more

expensive treatments at an earlier stage of the disease.

PMID: 16126795

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & list_uids=1\

6126795 & dopt=Abstract

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