Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Quantification of Periarticular Osteopenia in Rheumatoid Arthritis.

Ahn3,  Inhye E., Ju1,  Ji Hyeon, Kang2,  Kwi Young, Kwok1,  Seung-Ki, Park1,  Kyung-su, Park1,  Sung-Hwan, Kim1,  Ho-Youn

Department of Internal Medicine, Division of Rheumatology, Catholic University of Korea, Seoul, Korea, Republic of
Department of Internal Medicine, Division of Rheumatology, Chungbuk University, Cheongju, Korea, Republic of
Department of Internal Medicine, The Methodist Hospital, Houston, TX

Objectives:

By quantifying localized hand bone mineral density (BMD), we aimed to validate a new diagnostic method for evaluating the periarticular bone damage in rheumatoid arthritis (RA).

Methods:

The study enrolled 195 patients with polyarthritis and was conducted in three steps.

Table 1. Clinical and demographic features of patients and controls.

 RANon-RAPa
N (total=195)45150 
Sex (female/male)40/5113/370.881
Age (years), mean (SD)47.98 (16.36)48.24 (15.69)<0.05
BMI (kg/m2)22.06 (3.93)23.94 (3.28)0.262
L-spine T-score-1.22 (1.23)-0.80 (1.39)0.415
L-spine Z-score-0.23 (0.93)0.02 (1.23)0.099
Medications   
        Corticosteroids86.67%28.67% 
        Duration of corticosteroids treatment (years)4.36 (5.42)3.48 (3.79) 
        Biphosphonate28.89%17.33% 
        Calcium and/or Vitamin D supplements60.00%42.67% 
Morbidities & Comorbidities   
        Ostearthritis359 
        Crystal-induced arthropathy (eg. Gout)04 
        Systemic Lupus Erythematosus114 
        Sjogren's disease010 
        Dermatomyositis/Polymyositis16 
        Ankylosing Spondylitis139 
        Behcet's disease09 
        Others 2 Systemic sclerosis 1 Raymonds disease 1 Stills disease 5 Unspecified 
Abbreviations: SD: standard deviation. BMI: body mass index
a Mann-Whitney rank sum test for unpaired differences p under 0.05 was considered statistically significant.

First, inter-observer agreement of periarticular osteopenia in the conventional hand x-ray was evaluated. Second, BMDs of periarticular and non-periarticular regions were quantified by digital x-ray radiogrammetry (DXR). BMD ratios were calculated out of eight designated areas on proximal phalanges and compared between RA (n=45) versus non-RA (n=149) groups. Third, medical records of RA patients were retrospectively reviewed to identify clinical conditions predisposing to the loss of juxta-articular bone minerals.

Results:

The interpretation of periarticular osteopenia on x-ray reached a moderate degree of inter-observer agreement among four physicians (kappa 0.47, p<0.001). On DXR-assisted BMD quantification, we designed three types of mathematical formulae; the ratio of non-periarticular to periarticular BMD, the mean of ratios, and the ratio of sums.

Table 2. Periarticular osteopenia in RA versus non-RA patients

 Non-RATotal RARA<10YRA>=10Y
 mean (SD)mean (SD)pmean (SD)pmean (SD)p
N (total=195)150453112
Digits of left hand       
        Index: L1'/L11.85 (0.27)1.98 (0.47)*0.0182.10 (0.24)*<0.011.65 (0.44)*0.028
        Middle: L2'/L21.90 (0.33)1.97 (0.38)0.2492.07 (0.35)*0.0121.72 (0.37)0.079
        Ring: L3'/L32.03 (0.35)2.17 (0.58)*0.0412.25 (0.48)*<0.012.03 (0.78)0.949
        Small: L4'/L41.91 (0.37)2.06 (0.58)*0.0312.07 (0.40)0.0582.09 (0.92)0.144
Digits of right hand       
        Index: R1/R11.84 (0.31)1.93 (0.50)0.1192.04 (0.46)*<0.011.66 (0.53)0.099
        Middle: R2'/R21.85 (0.30)1.96 (0.44)0.0512.05 (0.40)*<0.011.64 (0.37)*0.034
        Ring: R3'/R32.00 (0.33)2.08 (0.40)0.2272.19 (0.31)*<0.011.87 (0.48)0.187
        Small: R4'/R41.94 (0.36)2.04 (0.52)0.2212.04 (0.49)0.2002.08 (0.64)0.233
Formulae       
        Left: mean of mid-to-peri BMD ratio1.92 (0.25)2.05 (0.40)*0.0122.12 (0.31)*<0.011.87 (0.56)0.589
        Right: mean of mid-to-peri BMD ratio1.91 (0.26)2.01 (0.35)0.0852.08 (0.28)*<0.011.81 (0.44)0.267
        Both: mean of mid-to-peri BMD ratio1.91 (0.24)2.03 (0.35)*0.0152.10 (0.26)*<0.011.84 (0.47)0.379
        Left: sum of mid BMD/sum of peri BMD1.90 (0.25)2.01 (0.38)*0.0332.09 (0.30)*<0.011.79 (0.48)0.182
        Right: sum of mid BMD/sum of peri BMD1.89 (0.26)1.97 (0.35)0.0882.05 (0.29)*<0.011.76 (0.43)0.132
        Both: sum of mid BMD/sum of peri BMD1.89 (0.24)1.98 (0.34)0.0582.06 (0.26)*<0.011.77 (0.43)0.107
aIndependent t-test to compare means of non-RA patients versus one of the three groups; all RA patients, RA under 10 years, RA for and over 10 years.
An asterisk (*) indicates a statistically significant difference with p value under 0.05 when compared to the non-RA group. Other unlabled values were not significant. Values are the mean (SD) in g/cm2.

These values were significantly higher in patients with RA for less than 10 years than in non-RA group (p<0.05). RA for 10 years or longer blunted the BMD ratios, and the disease duration was inversely correlated to the ratio (correlation coefficient -0.35).

Cut-off values were within 2.10–2.15 (sensitivity 36.67–80.64%, specificity 52.17–86.42%). In bivariate analysis, body mass index, the duration of steroids and c-telopeptide showed correlation with BMD ratios (p<0.05).

Conclusion:

In DXR-assisted localized quantification and proportional calculation, periarticular osteopenia is a distinctive feature of RA under 10 years of duration.

Clinical Trial Registration Number: KC09OISI0258

To cite this abstract, please use the following information:
Ahn, Inhye E., Ju, Ji Hyeon, Kang, Kwi Young, Kwok, Seung-Ki, Park, Kyung-su, Park, Sung-Hwan, et al; Quantification of Periarticular Osteopenia in Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1770
DOI: 10.1002/art.29535

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