Further analysis of the Glans-Urethral Meatus-Shaft (GMS) hypospadias score: Correlation with postoperative complications

Abstract

The Glans-Urethral Meatus-Shaft (GMS) score is a concise and reproducible way to describe hypospadias severity. We classified boys undergoing primary hypospadias repair to determine the correlation between GMS score and postoperative complications. Between February 2011 and August 2013, patients undergoing primary hypospadias repair were prospectively scored using the GMS classification. GMS scoring included a 1-4 scale for each component: G - glans size/urethral plate quality, M - meatal location, and S - degree of shaft curvature, with more unfavorable characteristics assigned higher scores [Figure]. Demographics, repair type, and complications (urethrocutaneous fistula, meatal stenosis, glans dehiscence, phimosis, recurrent chordee and stricture) were assessed. Total and individual component scores were tested in uni- and multivariate analysis. Two-hundred and sixty-two boys (mean age 12.3 ± 13.7 months) undergoing primary hypospadias repair had a GMS score assigned. Mean GMS score was 7 ± 2.5 (G 2.1 ± 0.9, M 2.4 ± 1, S 2.4 ± 1). Mean clinical follow-up was 17.7 ± 9.3 months. Thirty-seven children (14.1%) had 45 complications. A significant relationship between the total GMS score and presence of any complication (p < 0.001) was observed; for every unit increase in GMS score the odds of any postoperative complication increased 1.44 times (95% CI, 1.24-1.68). Urethrocutaneuous fistula was the most common complication, occurring in 21 of 239 (8.8%) of single-stage repairs. Patients with mild hypospadias (GMS 3-6) had a 2.4% fistula rate vs. 11.1% for moderate (GMS 7-9) and 22.6% for severe (GMS 10-12) hypospadias (p < 0.001). Degree of chordee was an independent predictor of fistula on multivariate analysis; S4 (>60° ventral curvature) patients were 27 times more likely to develop a fistula than S1 (no curvature) boys (95% CI, 3.2-229). The GMS score is based on anatomic features (i.e. glans size/urethral plate quality, location of meatus, and degree of chordee) felt to most likely impact functional and cosmetic outcomes following hypospadias repair. We demonstrated a statistically significant increase in the likelihood of any postoperative complication with every unit increase in total GMS score. The concept that factors aside from meatal location affect hypospadias repair and outcomes is not novel, and degree of ventral curvature and urethral plate quality are often cited as important factors. In our series, boys with greater than 60° of ventral curvature undergoing a single-stage repair were 27 times more likely to develop a fistula than those without chordee on multivariate analysis, making severe curvature an independent predictor of urethrocutaneous fistula formation. That meatal location did not retain significance on multivariate analysis highlights the importance of considering the entire hypospadias complex when determining severity, rather than just evaluating the position of the meatus. Our study has several limitations that warrant consideration. While GMS scores were assigned prospectively, the data was collected retrospectively, subjecting it to flaws inherent with such study design. Furthermore, type of repair is influenced by surgeon preference and subjective assessment of hypospadias characteristics not incorporated in our scoring system (i.e. tissue quality, urethral hypoplasia, penoscrotal transposition). Despite these limitations, our study demonstrates a strong correlation between the GMS classification and surgical complications, furthering supporting its potential as a tool to standardize hypospadias severity and gauge postoperative complications. The Glans-Urethral Meatus-Shaft (GMS) classification provides a means by which hypospadias severity and reporting can be standardized, which may improve inter-study comparison of reconstructive outcomes. There is a strong correlation between complication risk and total GMS score. Degree of chordee (S score) is independently predictive of fistula rate.