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.

Urolithiasis in Ankylosing SpondylitisAre Stone Formers Also Bone Formers?

Lui1,  Nai Lee, Carty5,  Adele, Haroon3,  Nigil, Shen2,  Hua, Cook2,  Richard, Inman4,  Robert D.

Department of Rheumatology and Immunology, Singapore General Hospital, Singapore
Department of Statistics and Actuarial Science, University of Waterloo, Canada
Division of Rheumatology, Toronto Western Hospital, Toronto, ON, Canada
Toronto Western Hospital, Toronto, ON, Canada
Toronto Western Hospital


The frequency with which urolithiasis occurs in patients with ankylosing spondylitis (AS) has not been systematically analyzed in a large cohort. Urolithiasis represents an inherent propensity for calcium precipitation and calcification which might influence the osteoproliferation process in AS. We performed a cross-sectional analysis to determine risk factors for stone formation in AS and to address differences association with clinical features and osteoproliferation profiles.


In a longitudinal study of 504 AS patients, we conducted an analysis of all AS patients who developed urolithiasis. All patients met the modified New York criteria for AS. Demographics, clinical features, extra-articular features and co-morbidities are recorded in the database. We compared disease activity, functional indices, medical therapy and radiographic damage using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) between AS patients with and without urolithiasis.


Thirty eight AS patients had a history of urolithiasis, a frequency of 7.5% in this AS cohort. Seventy six AS patients with no history of urolithiasis, matched for age, gender and ethnicity, were selected as controls. There was no difference in the incidence of urolithiasis in terms of gender, ethnic groups, HLA-B27 status, smoking history or alcohol consumption. AS patients with urolithiasis were more likely to have more functional disability, as measured by Bath AS Functional Index (BASFI) (mean 5.3 versus 3.6 in control group, p=0.003). There was trends toward higher Bath AS Disease Activity Index (BASDAI) (mean 4.9 versus 4.0, p=0.09), more peripheral joint involvement (p=0.075) and higher frequency of biologic therapy (p=0.09). However, no significant difference was detected in the mSASSS scores (p=0.65) or Bath AS Metrology Index (BASMI) (p=0.98). There was a significant association of urolithiasis with diabetes (p=0.016) and with Crohn's disease (p=0.006).


There is no acceleration of syndesmophyte formation or spinal fusion associated with urolithiasis in AS. But AS patients with urolithiasis have unexpectedly more functional disability than AS patients overall. The higher risk with concomitant DM or Crohn's disease should alert clinicians to these co-morbidities in AS patients developing urolithiasis.

To cite this abstract, please use the following information:
Lui, Nai Lee, Carty, Adele, Haroon, Nigil, Shen, Hua, Cook, Richard, Inman, Robert D.; Urolithiasis in Ankylosing SpondylitisAre Stone Formers Also Bone Formers? [abstract]. Arthritis Rheum 2010;62 Suppl 10 :556
DOI: 10.1002/art.28325

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