Validity and reliability of a smartphone application for the assessment of penile deformity in Peyronie's disease.

INTRODUCTION

Available methods to evaluate men with Peyronie's disease (PD) are limited by the inability to accurately and reproducibly measure penile deformity. AIM.: The study aims to evaluate the performance of a smartphone application for the measurement of penile curvature and narrowing.

METHODS

A smartphone application, the University of Washington Peyronie's Examination Network (UWPEN), was developed for this purpose. To assess penile curvature, 15 single cylinders of malleable penile prostheses were molded to varying curvature angles. Three blinded observers nonsequentially measured the angle of curvature for each prosthetic cylinder using a protractor, goniometer, and UWPEN. To assess girth narrowing, six clay models of the penile shaft were constructed to represent conditions of normal, partial hourglass, circumferential hourglass, and pencil narrowing. Girth was measured using a ruler and UWPEN by the same blinded observers.

MAIN OUTCOME MEASURES

Statistical analyses compared intertest, interobserver, and intraobserver reliability using the interclass correlation coefficient (ICC). An ICC above 0.75 indicates excellent reproducibility among measurements.

RESULTS

Intertest reliability for angle measurements yielded an ICC for the three methods of 1.000. Separately, the ICC for UWPEN vs. the goniometer and protractor was 0.999 and 0.999, respectively. The interobserver ICC for UWPEN, goniometer, and protractor was 0.998, 0.999, and 1.000, respectively. Intertest reliability for girth narrowing measurements yielded an ICC of 0.991. The interobserver ICC for girth narrowing for UWPEN and the ruler was 0.978 and 0.986, respectively. Intraobserver ICC for angle measurements and girth narrowing showed high reliability for all observers and methods.

CONCLUSIONS

The performance of UWPEN is comparable with and highly correlated with angle measurements obtained from the goniometer and protractor as well as with girth narrowing measurements obtained from a ruler. Measurements are reproducible among different observers. UWPEN may provide a noninvasive, accurate, reliable, and widely accessible method to characterize and track PD over time.