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Letter to the Editor

Reply to Parham Habibzadeh and Farrokh Habibzadeh's

Letter to the Editor re: Eric A. Klein, Arnon Chait,

Jason M. Hafron, et al. The Single-parameter, Structure-

based IsoPSA Assay Demonstrates Improved Diagnostic

Accuracy for Detection of Any Prostate Cancer and

High-grade Prostate Cancer Compared to a

Concentration-based Assay of Total Prostate-specific

Antigen: A Preliminary Report. Eur Urol 2017;72:942

9.

The Most Appropriate IsoPSA Cutoff for Diagnosis of

Prostate Cancer

The authors appreciate the

[1_TD$DIFF]

careful analysis of results from

our manuscript

[1]

regarding the selection of an optimal

operating cut-off point based on economic analysis.

Habibzadeh and Habibzadeh proposed optimizing an

equation combining specificity/sensitivity pairs from re-

ceiver operating characteristic analysis with pretest proba-

bility (prevalence), and with the relative cost of a false

negative to false positive. They further estimated the

optimal operating points from our plotted receiver operat-

ing characteristic curves and the reported prevalence for

several cost ratio scenarios. Utilization of such analysis is,

however, more difficult in practice since prevalence

and cost ratio are, as properly noted by Habibzadeh and

Habibzadeh, widely varying parameters that are functions

of test utilization, indications, geography, health care

system, and societal considerations, etc.

Therefore, while we agree with both the purpose and

analysis results by Habibzadeh and Habibzadeh, we believe

that in practice, until quantitative evaluation of cost ratio is

available and specific for each country, population, health

care system practices, and even individual preferences, it

would be difficult at best to implement in current clinical

practice. Furthermore, in our experience, even the variations

in individual preferences alone are so large, depending on

age, comorbidity, actual expense to the patient, etc., negating

use of anything more complicated than simple

[2_TD$DIFF]

reporting of

negative

[3_TD$DIFF]

predictive value, for example, to the clinician and to

the patient to make individual specific informed decisions.

We believe that reporting results

[2_TD$DIFF]

as negative

[3_TD$DIFF]

predictive

value using easy to comprehend language such as

your

IsoPSA test score corresponds to the exclusion value of 95%,

meaning that 95% of the patients with your test score or

below did not have cancer (or did not have high risk cancer,

etc.)

is arguably the best way to disseminate information to

the patient and his physician. This reporting style could then

be followed by a discussion between the patient and his

physician to determine the best course of action, considering

both quantifiable economic and less tangible parameters

unique to each case.

Conflicts of interest:

Eric A. Klein is employed by Cleveland Clinic, which

has an equity position in Cleveland Diagnostics; however, he has no

direct or indirect personal

fi

nancial interests in the company.

Reference

[1]

Klein EA, Chait A, Hafron JM, et al. The single-parameter, structure- based IsoPSA assay demonstrates improved diagnostic accuracy for detection of any prostate cancer and high-grade prostate cancer compared to a concentration-based assay of total prostate-speci fi c antigen: a preliminary report. Eur Urol 2017;72:942 9

.

Eric A. Klein*

Cleveland Clinic Foundation, Glickman Urologic and Kidney Institute,

Cleveland, OH, USA

*Cleveland Clinic Foundation, Glickman Urologic and Kidney Institute,

Q10 9500 Euclid Avenue, Cleveland, OH 44195, USA. Tel. +12164445601.

E-mail address:

kleine@ccf.org .

July 17, 2017

E U R O P E A N U R O L O GY 7 2 ( 2 0 17 ) e 174

available at

www.scienced irect.com

journal homepage:

www.europeanurology.com

DOIs of original articles:

http://dx.doi.org/10.1016/j.eururo.2017.06.028

,

http://dx.doi.org/10.1016/j.eururo.2017.03.025

.

http://dx.doi.org/10.1016/j.eururo.2017.07.020

0302-2838/© 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.