title: An inverse association of body mass index and prostate-specific antigen in northwest men of China: a population-based analysis.
abstract: OBJECTIVE
  To examine the relationship between body mass index (BMI) and prostate-specific antigen (PSA) in Chinese men and to investigate whether this relationship was independent of other factors.
  
  
  METHODS
  Cross-sectional analysis was in men aged 19 to 82 years old (N=12,964) who without prostate cancer and had health examination between 2008 and 2013 in a clinical center in Xi'an, China. Obesity and overweight were classified according to the WHO criterion. Mean PSA level was calculated by categories (normal weight, overweight, and obesity) and age group (≤ 40, 41-59, ≥ 60 years old). The association between BMI and PSA was examined using multivariate regression models and stratified by age.
  
  
  RESULTS
  The crude prevalence was 38.42% for overweight and 3.47% for obesity in the study population. Mean PSA level increased with age at each BMI category. BMI was negatively associated with PSA level at each age group, independent of fasting plasma glucose (FPG) and prostate volume. Per unit increase in BMI was associated with a decrease of PSA by 0.03 (P=0.05), 0.11(P < 0.001), and 0.15 (P < 0.001) in men aged ≤ 40, between 41 to 59, and > 60 years old, respectively.
  
  
  CONCLUSIONS
  Our results indicate that a higher BMI is associated with a lower level of PSA in healthy Chinese men across all age group, independent of prostate volume and FPG. With the current obesity epidemic, individual's BMI should be considered when PSA test is used to screen or diagnose prostate cancer.
authors.affiliation: Department of Nutrition, The First Affiliated Hospital of Medical School, Xi'an Jiaotong University Xi'an, China.
authors.forename: Jianqin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Geriatric Surgery, The First Affiliated Hospital of Medical School, Xi'an Jiaotong University Xi'an, China.
authors.forename: Binwu
authors.initials: B
authors.lastname: Sheng
authors.affiliation: Department of Geriatric Surgery, The First Affiliated Hospital of Medical School, Xi'an Jiaotong University Xi'an, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Ma
authors.affiliation: Department of Urology Institute, The First Affiliated Hospital of Medical School, Xi'an Jiaotong University Xi'an, China.
authors.forename: Xunyi
authors.initials: X
authors.lastname: Nan
keywords: China; Prostate-specific antigen; body mass index; northwest men; population-based analysis