Abstract B112: Dyadic associations of physical activity, diet quality, and body mass index in Black prostate cancer survivors and their spouses

Abstract Purpose: Black men bear a disproportionately high burden of prostate cancer (PCa), not only in terms of incidence and survival but also in survivorship outcomes, including poor quality of life and comorbidities. Lifestyle behaviors, such as physical activity and diet, are critical for maintaining a healthy body weight and preventing adverse health outcomes in Black PCa survivors. Spouses/significant others (hereafter spouses) can play a key role in shaping these behaviors. However, little is known about whether lifestyle behaviors are shared within couples or exert partner effects among Black PCa survivors. This study examined the concordance of lifestyle behaviors and body mass index (BMI) between Black PCa survivors and their spouses, and investigated how each individual’s physical activity and diet quality relate to their own and their spouse’s BMI. Methods: This cross-sectional secondary analysis included 93 dyads of Black PCa survivors and their spouses (i.e., N=186 individuals). Physical activity was measured using the International Physical Activity Questionnaire and diet quality using the Diet History Questionnaire III. The intraclass correlation coefficients (ICC) was used to assess within-couple concordance. Actor–Partner Interdependence Models (APIM), estimated using robust maximum likelihood and full-information likelihood, tested whether individual’s physical activity and diet quality predicted their own BMI (actor effects) and their spouse’s BMI (partner effects). Results: There was substantial within-couple concordance for physical activity (ICC = .315) and diet quality (ICC = .453), and small-to-moderate concordance for BMI (ICC = .093). Among survivors, there was a significant actor effect on diet quality: higher diet quality was significantly associated with their own lower BMI (β = –0.256, p = .023). The actor effect for physical activity was not statistically significant (β = –0.179, p = .059). Among spouses, no significant actor effects were found for physical activity (β = 0.180, p = .178) or diet quality (β = 0.042, p = .746). However, there was a significant partner effect showing that spouses’ physical activity was independently associated with lower survivor BMI (β = –0.183, p = .028). Additionally, higher spouse education was inversely associated with survivor BMI (β = –0.255, p = .001). Conclusions: This study provides evidence of interdependence between lifestyle behaviors and BMI among Black PCa survivors and their spouses, supporting the use of dyadic or family-based approaches in behavioral health research. The observed concordance and significant partner effects suggest that involving spouses in lifestyle interventions and enhancing their knowledge may increase the effectiveness of these interventions in reducing BMI and improving health outcomes among Black PCa survivors. Longitudinal studies are needed to investigate the factors that influence partner effects and to inform the development of culturally relevant lifestyle or weight management interventions for this underserved cancer population. Abstract Citation Format: Haejeong An, Seokhun Kim, Lorna H. McNeill, Curtis A. Pettaway, Dalnim Cho. Dyadic associations of physical activity, diet quality, and body mass index in Black prostate cancer survivors and their spouses [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr B112.