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.
Associations between Composite Measures of Multi-Joint Osteoarthritis, Gait Speed, and Health Assessment Questionnaire Scores: The Johnston County Osteoarthritis Project.
Nelson6, Amanda E., DeVellis5, Robert F., Renner5, Jordan B., Purser3, Jama, Schwartz5, Todd A., Conaghan1, Philip G., Kraus2, Virginia Byers
Chapel Allerton Hospital, Leeds, United Kingdom
Duke Univ Med Ctr, Durham, Durham, NC
Duke Univ Med Ctr, Durham, NC
Thurston Arthritis Research Center, Univ of North Carolina, Chapel Hill, Chapel Hill, NC
Thurston Arthritis Research Center, Univ of North Carolina, Chapel Hill, NC
UNC School of Medicine, Chapel Hill, NC
As there is no widely accepted definition of multi-joint osteoarthritis (OA), it is difficult to quantify the effect of multiple joint involvement on OA outcomes. We used factor analysis to create composite variables reflecting multi-joint radiographic OA, and determined associations between these variables and systemic outcomes (gait speed and health assessment questionnaire [HAQ] scores).
Data were from a cross-sectional sample of the Johnston County OA Project, including individuals with multi-joint radiographs, HAQ, and gait speed (n=1350, 66% women, 33% African Americans, mean age 67 ± 10 years, mean body mass index [BMI] 31 ± 6 kg/m2). HAQ scores were categorized as 0, 0 to < 1, or >= 1. Mean seconds to complete an 8-foot walk were converted to gait speed in m/s. Radiographs of the bilateral hands, tibiofemoral joints (TFJ), and hips were read for Kellgren-Lawrence grade (KL 04) at each joint. Lateral lumbosacral spine (LS) films were read for osteophytes (OST 03) and disc space narrowing (DN 03) at 5 levels, and patellofemoral joint (PFJ) radiographs were read for OST (03), using the Burnett atlas. During factor analysis using these scores, the hip and LS variables did not load onto factors and were assessed separately (Hip OA if KL >= 2 at either hip, LS OA if OST and DN >= 1 at a single level). Linear and partial proportional odds regression models for gait speed and HAQ, respectively, were used to determine associations between OA variables and outcomes, adjusting for age, BMI, gender, and race.
Factor analysis produced 3 factors. The 1st consisted of the 1st interphalangeal (IP) joints, distal IP joints 25, and proximal IP joints 25 (IP factor, a=0.96); the 2nd included the metacarpophalangeal joints 25 (MCP factor, a=0.81); the 3rd included TFJs and PFJs (Knee factor, a=0.87). The mean gait speed in the sample was 0.7 ± 0.2 m/s. Proportions by HAQ categories were 30% (0), 24% (> 0 to < 1) and 46% (>= 1). Gait speed was negatively associated with hip OA and the 3 factors, but the associations were greatly attenuated after adjustment (Table). For HAQ, a 1-SD increase in either the IP or knee factor resulted in 18% and 16% increased odds, respectively, of being in a higher HAQ category after adjustment (IP factor cumulative odds ratio [cOR]=1.18 [95% CI 1.031.36]; knee factor cOR 1.16 [95% CI 1.031.30]).
Association between composite factors representing multi-joint OA and functional outcomes.
Composite factors representing multi-joint OA involvement were associated with reduced gait speed and higher HAQ scores, although the estimates were attenuated by covariates, particularly age and BMI. Such composite factors can represent multiple joints in a single variable, reducing dimensionality and allowing more precise estimation of the effects of multi-joint OA involvement in models.
To cite this abstract, please use the following information:
Nelson, Amanda E., DeVellis, Robert F., Renner, Jordan B., Purser, Jama, Schwartz, Todd A., Conaghan, Philip G., et al; Associations between Composite Measures of Multi-Joint Osteoarthritis, Gait Speed, and Health Assessment Questionnaire Scores: The Johnston County Osteoarthritis Project. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :181