• Epidemiology Program, College of Health Sciences, University of Delaware, 100 Discovery Blvd., 7th floor, Newark, DE, 19713, USA. khans@udel.edu.
• Coeus Health, 222 W Merchandise Mart Plaza, Chicago, IL, 60654, USA.
• Division of Public Health Sciences, Department of Surgery, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave., Campus Box 8100, St. Louis, MO, 63110, USA.
• Department of Urology, Medical University of South Carolina, 135 Rutledge Ave, Charleston, SC, 29425, USA.
• Westat, 1600 Research Blvd, Rockville, MD, 20850, USA.
• Information Management Services, Inc., 1455 Research Blvd, Suite 315 , Rockville, MD, 20850, USA.
• Departments of Urology and Epidemiology and Biostatistics, University of California - San Francisco, 400 Parnassus Ave # 610, San Francisco, CA, 94143, USA.
• Division of Urologic Surgery, Department of Surgery, Washington University in St. Louis School of Medicine, 4921 Parkway Place, St. Louis, MO, 63110, USA.

BACKGROUND: Existing evidence suggests that there is an association between body size and prevalent Benign Prostatic Hyperplasia (BPH)-related outcomes and nocturia. However, there is limited evidence on the association between body size throughout the life-course and incident BPH-related outcomes.

METHODS: Our study population consisted of men without histories of prostate cancer, BPH-related outcomes, or nocturia in the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) (n = 4710). Associations for body size in early- (age 20), mid- (age 50) and late-life (age ≥ 55, mean age 60.7 years) and weight change with incident BPH-related outcomes (including self-reported nocturia and physician diagnosis of BPH, digital rectal examination-estimated prostate volume ≥ 30 cc, and prostate-specific antigen [PSA] concentration > 1.4 ng/mL) were examined using Poisson regression with robust variance estimation.

RESULTS: Men who were obese in late-life were 25% more likely to report nocturia (Relative Risk (RR): 1.25, 95% Confidence Interval (CI): 1.11-1.40; p-trend_{for continuous BMI} < 0.0001) and men who were either overweight or obese in late-life were more likely to report a prostate volume ≥ 30 cc (RR_overweight: 1.13, 95% CI 1.07-1.21; RR_obese: 1.10, 95% CI 1.02-1.19; p-trend_{for continuous BMI} = 0.017) as compared to normal weight men. Obesity at ages 20 and 50 was similarly associated with both nocturia and prostate volume ≥ 30 cc. Considering trajectories of body size, men who were normal weight at age 20 and became overweight or obese by later-life had increased risks of nocturia (RR_{normal to overweight}: 1.09, 95% CI 0.98-1.22; RR_{normal to obese}: 1.28, 95% CI 1.10-1.47) and a prostate volume ≥ 30 cc (RR_{normal to overweight}: 1.12, 95% CI 1.05-1.20). Too few men were obese early in life to examine the independent effect of early-life body size. Later-life body size modified the association between physical activity and nocturia.

CONCLUSIONS: We found that later-life body size, independent of early-life body size, was associated with adverse BPH outcomes, suggesting that interventions to reduce body size even late in life can potentially reduce the burden of BPH-related outcomes and nocturia.