External Validation of Triple D Score in an Elderly (≥65 Years) Population for Prediction of Success Following Shockwave Lithotripsy

Abstract

Introduction:

Triple D score was recently developed for prediction of extracorporeal shockwave lithotripsy (SWL) outcomes. However, it has not been validated. SWL in elderly patients results in lower success and higher complication rates. We aimed at externally validating Triple D score in a population ≥65 years of age.

Patients and Methods:

We retrospectively analyzed the data of 182 patients ≥65 years of age who underwent SWL for renal or ureteral stones and were evaluated with non-contrast computed tomography before SWL. Stone volume (SV), skin-to-stone distance (SSD), and stone density were measured, and cutoff values were determined with receiver operator characteristic analysis. Triple D scores were calculated, and success rates were determined for each score.

Results:

Mean SV, SSD, and stone density values were significantly higher in patients with failed outcomes compared with those with successful outcomes in both renal and ureteral cases. Cutoff values of 187.5 mm³, 10.5 cm, and 675 HU for renal stones and of 185 mm³, 11.5 cm, and 785 HU for ureteral stones were detected. Success rates of 95.5% and 95% were detected for patients with a Triple D score of 3 in the renal and ureteral stone groups, respectively. Success rates of patients with a Triple D score of 0 were 20% and 25% in the renal and ureteral stone groups, respectively.

Conclusions:

Triple D score correlated well with SWL outcomes in patients ≥65 years of age, and it is externally validated. Various factors may deal with cutoff levels of involved parameters. Therefore, we suggest that each institution determines its unique cutoff levels for SV, SSD, and stone density parameters and calculates the Triple D score for its patients with respect to these cutoff levels to predict the success after SWL and aid in decision making.