Black-white disparity in physical performance among older women with breast cancer: The role of physical activity and inflammation.

Abstract

6525 Background: Compared with non-Hispanic Whites (NHW), African-Americans (AA) experience poorer physical function. However, little is known about the existence of racial disparity in physical performance among older adults with cancer, and clinical factors that might explain such differences. Methods: This is a cross-sectional study of women ≥ 65 years (n=108), with stage I-III breast cancer. Before adjuvant treatment, participants completed the Short Physical Performance Battery (SPPB), an objective measure of lower extremity function on a scale of 0-12, with higher scores denoting higher physical performance. Self-reported physical activity was ascertained with the Minnesota Leisure Time Activity Questionnaire. Serum level of C-reactive protein (CRP) was determined and log transformed for analyses. Results: The median age was 74.0 years (range 65-93 years) and 32% were AA. The mean SPPB score was 8.5 (SD 3.5). Compared to NHW, AA had lower mean SPPB scores (7.0 vs. 9.2, p=0.002), were less physically active (8.2 vs. 19.4 MET-hours/week, p=0.005), and had higher mean serum CRP(log) (-0.43 vs. -0.86, p=0.002). In multivariate linear regression analysis that accounted for age, educational status, comorbidities and geriatric syndromes, AA race relative to NHW was independently associated with decreasing SPPB scores, [beta coefficient = -1.67, SE: 0.57, p=0.004]. When differences in serum CRP and physical activity were accounted for in the model, increasing CRP and decreasing physical activity were independently associated with decreasing SPPB scores, and eliminated the racial difference in physical performance by 23% and 40%, respectively. This suggests sub-clinical inflammation and physical activity mediate the relationship between race and physical performance. Conclusions: Among older women with breast cancer, racial disparity in physical performance may be reduced through increased physical activity and therapeutic strategies that moderate sub-clinical inflammation. Given the clinical importance of functional status in cancer treatment decision-making, interventions directed at attenuating racial disparity in physical performance are warranted.