Evaluating the Children's Hospital of Alabama endoscopic third ventriculostomy experience using the Endoscopic Third Ventriculostomy Success Score: an external validation study

Object. Endoscopic third ventriculostomy (ETV) success is dependent on patient characteristics including age, origin of hydrocephalus, and history of shunt therapy. Using these factors, an Endoscopic Third Ventriculostomy Success Score (ETVSS) model was constructed to predict success of therapy. This study reports a single-institution experience with ETV and explores the ETVSS model validity. Methods. A retrospective chart review identified 151 consecutive patients who underwent ETV at a pediatric hospital between August 1995 and December 2009. Of these 151, 136 patients had at least 6 months of clinical follow-up. Data concerning patient characteristics, operative characteristics, radiological findings, complications, and success of ETV were collected. The actual success rates were compared with those predicted by the ETVSS model. Results. The actual success rate of ETV at 6 months was 68.4% (93 of 136 patients), which compared well to the predicted ETVSS of 76.5% +/- 12.5% (+/- SD). The C-statistic was 0.74 (95% CI 0.65-0.83), suggesting that the ability of the ETVSS to discriminate failures from successes was good. Secondary ETV was found to have a hazard ratio for failure of 4.2 (95% CI 2.4-7.2) compared with primary ETV (p < 0.001). The complication rate was 9.3% with no deaths. At the first radiological follow-up, the increased size of ventricles had a hazard ratio for failure of 3.0 (95% CI 1.5-6.0) compared with patients in whom ventricle size either remained stable or decreased (p = 0.002). Conclusions. The ETVSS closely predicts the actual success of ETV, fitting the statistical model well. Shortcomings of the model were identified in overestimating success in patients with ETVSS <= 70, which may be attributable to the poor success of secondary ETVs in the authors' patient population. (DOI: 10.3171/2011.8.PEDS1145)