7 Prognosis of Cartilage Loss by Analyzing Magnetic Resonance Imaging of the Tibia Trabecular Bone Structure (original) (raw)

Osteoarthritis and Cartilage

such as depression, can increase an individual's experience of pain. We used factor analysis to determine the relationships among symptomatic and psychosocial variables in a community-based sample with and without OA. Methods: We used data from individuals who were both enrolled in both the Johnston County OA Project and the separately funded Arthritis, Coping, & Emotion (ACE) study (data collected 1999-2005, n = 2239). This sample was approximately 1/3 male and African American, with mean age of 65±11 years, body mass index 30±7 kg/m2, and 13±11 years of education. Half had radiographic OA (defined as a Kellgren-Lawrence grade ≥2) of at least one hip or knee. Symptomatic data were available for 9 joint sites: the lower back and bilateral hands, knees, hips, and feet, and were graded as none, mild, moderate, or severe "on most days." The 7 validated psychosocial scales used were: the Centers for Epidemiological Studies Depression Scale (CES-D), Positive and Negative Affect Scale (PANAS), Rheumatology Attitudes Index (RAI), Social Support, Pain Catastrophizing Helplessness Subscale, Arthritis Impact Measurement Scale 2 Tension and Anxiety Subscale (AIMS2), and Life Orientation Test (LOT). Symptomatic data and the 7 scales were individually factor analyzed and appropriate composite scores were constructed. Higher order factor analysis was used to determine the relationships among these 8 composite scores. Cronbach's alpha was calculated as a measure of reliability and internal consistency. Analyses stratified by gender, race (African American vs. Caucasian), age (<55, 55-65, 65-75, 75+ years), body mass index (BMI, <25, 25 to <30, 30+ kg/meter squared), education (less than, equal to, or more than 12 years) and by radiographic OA status in the hip or knee were performed to determine any subgroup differences. Results: Analysis of each of the individual scales resulted in a single factor (all alphas >0.79) with the exception of the PANAS, which, as expected, had 2 factors (alpha 0.90) reflecting positive and negative affect characteristics. Symptoms from 9 joint sites also loaded onto a single factor (alpha 0.86). Higher order factor analysis using composite scores for each of these factors produced a single factor with an eigenvalue of 3.73 (See figure, due to missing values in individual scales, n = 1332, loadings 0.40-0.88, alpha 0.84). Dropping each score individually did not substantially change the alpha. Consistent results (factor loading pattern and alpha) were obtained when stratified by gender, race, age, BMI, education, or OA status. Figure: Screeplot of higher order factor and table of loadings of each scale onto this factor. *The eigenvalue represents the amount of information contained in a factor, while loadings represent the association between the individual scores and the factor.