Development and internal validation of a novel PHI-nomogram to identify aggressive prostate cancer.

BACKGROUND: Prostate Health Index (PHI) is a new test for the detection of prostate cancer (PCa), which improves the performance of total PSA (tPSA) and is related to tumor aggressiveness. The aim of our study was to construct a nomogram based in a multivariate model incorporating PHI to estimate the individual probability of aggressive PCa. METHODS: 276 subjects selected for biopsy were enrolled in our study, including 151 patients with PCa. D'Amico criteria were used to classify these patients in three groups related to risk of progression. Intermediate and high-risk PCa were considered as aggressive PCa. Multivariable models to predict aggressive PCa were constructed using laboratory (tPSA, %fPSA, %p2PSA, PHI) and clinical variables. The best prediction model was graphically presented as a nomogram for clinical use. RESULTS: The highest accuracy (AUC: 0.815) was obtained for a multivariate model including age, digital rectal examination, tPSA, %fPSA, PHI and prostate volume. DCA was performed to confirm the usefulness of this nomogram, showing a higher net clinical benefit (greater than 7%) compared to the base model which included age, digital rectal examination and tPSA. CONCLUSION: PHI-based nomogram is a useful tool for the detection of aggressive PCa.

Comparison of total, free and bioavailable 25-OH vitamin D determinations to evaluate its biological activity in healthy adults: the LabOscat study.

Determination of different forms of 25-OHD (total, free and bioavailable) in healthy young women does not offer additional advantages over standard 25-OHDT for evaluating vitamin D deficiency. In these subjects 25-OHDT values <15 ng/ml would be more appropriate for defining this deficiency. INTRODUCTION: Determination of 25-OH vitamin D serum levels (25-OHD) constitutes the method of choice for evaluating vitamin D deficiency. However, vitamin D-binding protein (DBP) may modulate its bioavailability thereby affecting correct evaluation of 25-OHD status. We analysed the impact of the determination of 25-OHD (total, free and bioavailable) on the evaluation its biologic activity (estimated by serum PTH determination) in healthy young women. METHODS: 173 premenopausal women (aged 35-45 yrs.) were included. We analysed serum values of total 25-OHD (25-OHDT), DBP, albumin, PTH and bone formation (PINP,OC) and resorption (NTx,CTx) markers. Free(25-OHDF) and bioavailable (25-OHDB) serum 25-OHD levels were estimated by DBP and albumin determinations and also directly by ELISA (25-OHDF-2). We analysed threshold PTH values for the different forms of 25-OHD and the correlations and differences according to 25-OHDT levels <20 ng/ml. RESULTS: 62% of subjects had 25-OHD values <20 ng/ml and also had significantly lower 25-OHDF and 25-OHDB values, with no significant differences in bone markers and PTH values. The PTH threshold value was similar for all forms of 25-OHD (∼70 pg/ml). Women with PTH values >70 had lower 25-OHDT (15.4 ± 1.4 vs. 18.3 ± 2.7, p < 0.05) and 25OHDB values (1.7 ± 0.2 vs. 2.2 ± 0.09, p < 0.05). The different forms of 25OHD were significantly intercorrelated, with marginal correlations between PTH and 25-OHDT (r = -0.136, p = 0.082). CONCLUSIONS: Determination of different forms of 25-OHD in healthy young women does not offer additional advantages over standard 25-OHDT for evaluating vitamin D deficiency. In these subjects 25-OHDT values <15 ng/ml would be more appropriate for defining this deficiency.

Variability of assay methods for total and free PSA after WHO standardization.

The variability of total PSA (tPSA) and free PSA (fPSA) results among commercial assays has been suggested to be decreased by calibration to World Health Organization (WHO) reference materials. To characterize the current situation, it is necessary to know its impact in the critical cutoffs used in clinical practice. In the present study, we tested 167 samples with tPSA concentrations of 0 to 20 µg/L using seven PSA and six fPSA commercial assays, including Access, ARCHITECT i2000, ADVIA Centaur XP, IMMULITE 2000, Elecsys, and Lumipulse G1200, in which we only measured tPSA. tPSA and fPSA were measured in Access using the Hybritech and WHO calibrators. Passing-Bablok analysis was performed for PSA, and percentage of fPSA with the Hybritech-calibrated access comparison assay. For tPSA, relative differences were more than 10 % at 0.2 µg/L for ARCHITECT i2000, and at a critical concentration of 3, 4, and 10 µg/L, the relative difference was exceeded by ADVIA Centaur XP and WHO-calibrated Access. For percent fPSA, at a critical concentration of 10 %, the 10 % relative difference limit was exceeded by IMMULITE 2000 assay. At a critical concentration of 20 and 25 %, ADVIA Centaur XP, ARCHITECT i2000, and IMMULITE 2000 assays exceeded the 10 % relative difference limit. We have shown significant discordances between assays included in this study despite advances in standardization conducted in the last years. Further harmonization efforts are required in order to obtain a complete clinical concordance.