Extracorporeal shock wave lithotripsy (ESWL) is a minimally invasive treatment for urinary
stones, but optimizing shock wave intensity remains challenging due to its nonlinear effects on treatment
outcomes. This study investigates these effects through subgroup analysis of clinical factors to develop
a novel framework for enhancing ESWL success. A dataset of 500 cases treated between 2019 and 2022
was analyzed. Patients were divided into subgroups based on clinical factors such as stone size, location,
and CT values. Statistical significance was assessed using Welch’s t-tests for subgroup analysis, and
multivariate Lasso regression was employed to evaluate independent predictors. For stones ≥ 9 mm, the
total energy delivered, calculated as the product of shock wave intensity and the number of shocks, significantly
impacted fragmentation success (mean total energy: success group 2.6 ± 0.4 J, failure group
2.1 ± 0.3 J; p < 0.05). In contrast, for stones < 9 mm or across ungrouped data, no significant effects
were observed. These findings highlight the importance of subgrouping for understanding nonlinear relationships
and suggest that total energy delivered is a more reliable predictor of success for larger
stones. The results emphasize the potential to develop individualized ESWL protocols by optimizing total
energy delivered, ultimately improving treatment outcomes. This study bridges statistical methods with
clinical protocols, providing actionable insights to reduce treatment failure and the burden on patients.
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