Original Article Age-specific reference range of prostate ...

Int J Clin Exp Med 2018;11(2):1376-1382 /ISSN:1940-5901/IJCEM0064678

Original Article Age-specific reference range of prostate-specific antigen in a population-based single-center study in the north of China

Li-Bin Nan, Xiao-Tao Yin, Fang-Long Li, Zhi-Qiang Shao, Yong Xu, Gang Guo, Jie Tang, Jiang-Ping Gao, Xu Zhang

Department of Urology, Chinese People's Liberation Army General Hospital, Beijing 100853, China

Received August 30, 2017; Accepted January 5, 2018; Epub February 15, 2018; Published February 28, 2018

Abstract: The goal of this study was to explore the relationship between age and serum prostate-specific antigen (PSA) levels in a healthy population in northern China and to establish the normal age-specific PSA reference levels. Clinical data were collected from healthy men who underwent routine health check-ups from July 2009 to September 2015. The enrolled men were classified into six groups by 10-year intervals, namely 30-39, 40-49, 5059, 60-69, 70-79, and 80-89. Correlations between age and normal PSA levels were analyzed. The 95th percentile range of each group was determined as the corresponding normal references of age-specific PSA, which were then compared with other studies from China and Western countries. A total of 24,194 men were included in this study. Serum PSA level was positively correlated with age (r=0.27, P4 ng/mL, abnormal percent free PSA (% fPSA) was defined as 0.15 [12]. Abnormal transrectal ultrasonography (TRUS) findings were defined as capsular irregularity, deformation, or existence of a hypoechoic region/nodule. Inclusion criteria: (1) serum PSA level 4 ng/mL, TRUS normal; (2) 4 ng/mL < serum PSA level 10 ng/mL, TRUS and % fPSA and PSAD normal; (3) % fPSA and/or PSAD abnormal with negative prostate biopsy result; (4) 10 ng/mL < serum PSA level 20 ng/mL, negative prostate biopsy result. Exclusion criteria: (1) history of prostate cancer/surgery; (2) taking androgen antagonists, urinary tract infection, prostatitis, massage of prostate, cystoscopy, or prostate biopsy before the PSA test; (3) serum PSA level >20 ng/mL because of the greater probability of undetected prostate cancer. Prostate biopsy criteria: (1) serum PSA level 4 ng/mL, TRUS abnormal; (2) 4 ng/mL < serum PSA level 10 ng/mL, % fPSA and/or PSAD abnormal; (3) serum PSA level >10 ng/mL.

Diagnostic equipment and method

Serum total PSA (tPSA) levels and free PSA (fPSA) levels were measured by LIAISON-XL, DiaSorin (Italy) chemiluminesence. TRUS was performed with Acuson Sequoia 512 (Siemens Medical Solutions USA). Prostate volume (PV) was measured via TRUS, before prostate biopsy. PV was defined by measuring the height (H), width (W), and length (L) of the prostate from two selected orthogonal views and was calculated using the ellipsoid volume formula: PV (ml)=0.52 ? W (cm) ? H (cm) ? L (cm) [13]. % fPSA was calculated by dividing fPSA (ng/ml) by tPSA (ng/ml). PSAD (ng/ml/ml) was calculated by dividing tPSA (ng/ml) by PV (ml). TRUSguided 12-core needle biopsies were performed. All patients had signed the informed consent before taking the prostate biopsy.

Statistical analysis

The results in this study were analyzed using SPSS software (version 17.0, Chicago, USA). R software (version 3.3.1, Auckland, NZL) was

used for serum PSA percentiles graphing. Subjects were divided into six age groups by 10-year intervals, namely, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89. The descriptive statistics, including the mean, standard deviation (SD), median, interquartile range (IQR, 75 th-25 th), 5th, 25th, 75th, and 95th percentiles of the serum PSA level were calculated for each 10-year age group. The 95th percentile values were determined as the upper limits of each 10-year age group for the serum PSA levels. Spearman's rank correlation coefficients were calculated to measure the association between serum PSA and age and Kruskal-Wallis ANOVA was used to compare differences of serum PSA level among each 10-year age group. The Kolmogorov-Smirnov test showed that the distribution differed significantly from the Gaussian curve for the total age group. Asymmetry was evaluated by calculation of the coefficients of skewness. P10 ng/mL, 544 cases. 2285 cases had prostate biopsy (9.26%), and 491 cases were diagnosed with PCa (1.99% of all screening, 21.49% of all prostate biopsy). The remaining 24,194 cases, who had no evidence of prostate cancer by any of the diagnostic tests, formed the study population on which the results of this study are based (Figure 1).

Distribution of serum PSA levels

According to the normality test (Z=36.418, p4 ng/ml

Total

Serum PSA level (ng/ml)

Percentile value

Mean ? SD Median 25th, 75th IQR 5th, 95th

30-39 1906 (99.9)

2 (0.1)

1908 (7.9) 0.81?0.58 0.67 0.46/1.01 0.55 0.28/1.79

40-49 7476 (99.9)

9 (0.1) 7485 (31.0) 0.86?0.61 0.7 0.49/1.05 0.56 0.28/1.92

50-59 7131 (98.8) 87 (1.2) 7218 (29.8) 1.06?1.20 0.78 0.51/1.23 0.72 0.27/2.63

60-69 3823 (93.4) 272 (6.6) 4095 (16.9) 1.67?2.14 1.03 0.59/1.89 1.3 0.26/4.41

70-79 2328 (86.5) 363 (13.5) 2691 (11.1) 2.27?2.68 1.4 0.72/2.81 2.09 0.25/6.20

80-89 695 (87.2) 102 (12.8) 797 (3.3) 2.22?2.34 1.5 0.73/2.91 2.18 0.14/6.54

Total 23359 (96.5) 835 (3.5) 24194 (100) 1.25?1.60 0.82 0.52/1.36 0.84 0.27/3.46

PSA=prostate-specific antigen; SD=standard deviation; IQR=interquartile range.

Table 2. Correlation analysis of age and serum PSA levels

Serum PSA levels among

Serum PSA

Age (years)

levels

30-39 40-49 50-59 60-69 70-79 80-89 Total

Chinese, different regions, and different races

r

-0.023 0.017 0.083 0.105 0.043 -0.061 0.27

P

0.313 0.133 ................
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