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.

Gender Differences in the Correlation of Self-Reported Functional Status with Spinal Mobility in Patients with Ankylosing Spondylitis.

Patel1,  Pooja N., Sharif2,  Roozbeh, Assassi3,  Shervin, Gensler4,  Lianne S., Diekman5,  Laura A., Learch6,  Thomas J., Weisman7,  Michael H.

University of Texas, Houston, Houston, TX
University of Texas Health Science Center at 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


Spinal damage in patients with ankylosing spondylitis (AS) can result in physical limitation. Previous studies have reported clinical and psychological factors correlate with self-reported functional status in AS patients. In the current study, the association of functional status with measurements of spinal mobility (AS-Metrology) was evaluated. Also examined was the the impact of gender, disease duration, and anti-tumor necrosis factor (TNF)a treatment on this association.


Patients enrolled in the Prospective Study of Outcomes in Ankylosing Spondylitis (PSOAS) cohort were studied. PSOAS is a multi-ethnic, multi-center cohort of patients with AS in the United States. The study investigators performed the following measurements of spinal mobility: cervical rotation and flexion, occiput-to-wall distance, chest expansion, modified Schober, lateral lumbar flexion, and hip internal/external rotation. In addition, the patients' perceived functional limitation was recorded by the Bath AS Functional Index (BASFI). Linear regression was used to examine the association of the BASFI score with concomitantly recorded spinal mobility measures at enrollment. Considering potential effect modifiers, the interaction term of BASFI with the following variables was examined: disease duration, gender, and anti-TNF a treatment.


Overall, 436 patients were included in the analysis: median age of 42.3 years, 70% male, 77% Caucasian, and median disease duration of 16.3 years. HLA-B27 was detected in 85% of subjects. BASFI score correlated with AS-Metrology (p<0.001). The analysis of potential effect modifiers indicated the presence of a statistically significant interaction between gender and BASFI with regard to its association with AS-Metrology (p<0.05). Subgroup analysis based on the gender indicated male patients have a stronger correlation between BASFI and AS-Metrology, compared to female patients (table-1). Though some of the AS-Metrology variables were not normally distributed, analysis of log transformed variables did not affect the results.


AS-Metrology is associated with BASFI score and this correlation is statistically stronger among men compared to women. These findings support the hypothesis that other factors might play an important role in perceived functional status among women with AS.

Table 1. Subgroup analysis of correlation between BASFI and AS metrology based on gender

Clinical measurementsBASFI* score
Correlation coefficientp-valueCorrelation coefficientp-value 
Cervical rotation-0.53<0.001-0.43<0.001
Cervical flexion-0.37<0.001-0.36<0.001
Occiput-to-wall distance0.48**<0.0010.240.011
Chest expansion-0.50**<0.001-0.290.002
Modified Schober-0.41**<0.001-0.190.048
Lateral flexion-0.49<0.001-0.48<0.001
Hip external rotation-0.29**<0.001-0.080.422
Hip internal rotation-0.36**<0.001-0.140.168
*BASFI: Bath Ankylosing Spondylitis Functional Index;**The magnitude of effect is statistically higher in men, compared to women

To cite this abstract, please use the following information:
Patel, Pooja N., Sharif, Roozbeh, Assassi, Shervin, Gensler, Lianne S., Diekman, Laura A., Learch, Thomas J., et al; Gender Differences in the Correlation of Self-Reported Functional Status with Spinal Mobility in Patients with Ankylosing Spondylitis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :505

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