Category: Clinical Stones: Medical Management

MP10-19 - The Luebeck Nomogram for the prediction of uric acid stones

Fri, Sep 21
2:00 PM - 4:00 PM

Introduction & Objective :

The oral chemolysis is an effective option for uric acid stone treatment. Proper patients’ selection plays however a crucial role in effective therapy.


The aim of our study was to propose a structured pre-therapeutic pattern predicting successful oral chemolysis.


Methods :

We conducted a retrospective monocentric analysis of the patients with a singular ureteral calculi and available stone analysis (n=459) treated between January 2014 und May 2016 at our department. Univariate statistics were applied to determine the differences, regarding 9 preoperative factors, between uric acid stone formers and patients with stones of other origin. 


Based on binary logistic regression we proposed a nomogram predicting the probability of uric stone presence.


Results :

Univariate analysis revealed significant differences (p<0.05) regarding the body mass index , age, uric acid blood level, mean hounsfield units (HU), x-ray characteristics and urin pH between the groups. Uric acid level was higher then 374,35 µmol/l in 75% of the patients in the uric acid stone group, but only of 25,88% of the other ones. The mean value was 434 ± 105,36 µmol/l vs. 337,63 ± 88,79 µmol/l. Stone location, stone size as well as DJ stent size were independent from the stone composition (p>0.05).
A nomogram predicting a presence of uric acid stones has been developed based on overmentioned significant parameters. Additionally we designed a test based on a ROC analysis in 2 variants. It demonstrated 71,1% sensitivity and 71,1% positive predictive value (PPV) or 48,9% sensitivity and 84,6% PPV.


Conclusions : Application of proposed models helps to identify the patients suitable for an oral chemolysis. We present a tool helpful for counselling patients about a tailored stone treatment. Further prospective studies confirming the clinical value of our nomogram are needed.

Judith R. Wiessmeyer

Fellow
University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany

Tomasz Ozimek

University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany

Michael H. Schneider

University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany

Jens Cordes

University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany

Axel S. Merseburger

University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany

Mario W. Kramer

University Hospital Schleswig-Holstein (Campus Luebeck)
Luebeck, Schleswig-Holstein, Germany