Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


How Does Disease Duration Modify the Association of Radiographic Damage with Ankylosing Spondylitis Metrology?

Sharif1,  Roozbeh, Patel2,  Pooja N., Assassi3,  Shervin, Gensler4,  Lianne S., Diekman5,  Laura A., Learch6,  Thomas J., Weisman7,  Michael H.

University of Texas Health Science Center at Houston, Houston, TX
University of Texas, Houston, Houston, TX
Univ of Texas Health Science, Houston, TX
UCSF, San Francisco, CA
UT Health Science Center, Houston, TX
Cedars-Sinai, Los Angeles, CA
Cedars Sinai Med Ctr, Los Angeles, CA
NIAMS/NIH, Bethesda, MD

Background/Purpose:

Previous studies have indicated that radiographic damage is associated with measurements of spinal mobility in patients with ankylosing spondylitis (AS). In the current study, we investigated the correlation of radiographic damage with spinal mobility and examined the impact of gender, disease duration, and anti-tumor necrosis factor (TNF) treatment on this association.

Methods:

Study population were participants in the Prospective Study of Outcomes in Ankylosing Spondylitis (PSOAS), a multi-ethnic, multi-center cohort of AS patients in the United States. The study investigators performed the following measurements (AS-Metrology): cervical rotation and flexion, occiput to wall distance, chest expansion, modified Schober, lateral spinal flexion, and hip internal/external rotation. One radiologist (TJL) read all cervical, pelvic, and spinal radiographs. Bath AS Radiologic Index-spinal (BASRI-s) was calculated. We used linear regression to examine the association of AS-Metrology and BASRI-s. We considered the possibility that certain factors might modify this association and examined the interaction term of disease duration, gender, and anti-TNF treatment with BASRI-s in regard to its association with AS-Metrology.

Results:

We included 436 patients in the analysis: 70% male, 77% Caucasian, and 85% HLA-B27 positive. Median age and disease duration was 42.3 and 16.3 years, respectively. The BASRI score was associated with all AS-Metrology components (p<0.001) except hip external rotation (p=0.223). The analysis of potential effect modifier indicated presence of a significant interaction between disease duration and BASRI in regard to its association with AS Metrology (p<0.05), while gender and anti-TNF treatment were not effect modifiers. Therefore, we categorized the patient into three groups based on disease duration at enrollment: less than 10, 10 to 20; and more than 20 years and conducted subgroup analysis. Patients with 10 to 20 years of symptoms demonstrated the highest correlation coefficient between BASRI and AS-Metrology (Table-1). Some of AS-Metrology variables were not normally distributed. Although, analysis of log transformed variable did not make any difference in outcome.

Table 1. Subgroup analysis of correlation between BASRI and AS metrology according to disease duration

 BASRI-s*
Clinical measurementsDisease duration**<= 10 years (n=126)Disease duration 10–20 years (n=95)Disease duration >= 20 years (n=114)
 Rp-valueRp-valueRp-value
Cervical rotation-0.35<0.001-0.66<0.001-0.44<0.001
Cervical flexion-0.220.011-0.68<0.001-0.58<0.001
Occiput to wall0.55<0.0010.70<0.0010.52<0.001
Chest expansion-0.300.001-0.45<0.001-0.36<0.001
modified Schober-0.46<0.001-0.69<0.001-0.47<0.001
Lateral spinal flexion-0.48<0.001-0.72<0.001-0.43<0.001
Hip external rotation0.140.113-0.230.011-0.130.175
Hip internal rotation0.050.577-0.300.003-0.140.128
*BASRI-s: Bath Ankylosing Spondylitis Radiology Index-spinal;
**Disease duration calculated from the onset of symptom until enrollment in PSOAS cohort;R: Correlation coefficient.

Conclusion:

AS-Metrology is associated with BASRI. This correlation peaks 10 to 20 years after the onset of symptoms and is weaker in earlier and later stages of disease.

To cite this abstract, please use the following information:
Sharif, Roozbeh, Patel, Pooja N., Assassi, Shervin, Gensler, Lianne S., Diekman, Laura A., Learch, Thomas J., et al; How Does Disease Duration Modify the Association of Radiographic Damage with Ankylosing Spondylitis Metrology? [abstract]. Arthritis Rheum 2011;63 Suppl 10 :2531
DOI:

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