Are renal tumour scoring systems better than clinical judgement at predicting partial nephrectomy complexity?

INTRODUCTION: We aimed to determine how renal tumour scoring systems, such as RENAL, PADUA, and Centrality (C)-index, compare to clinical judgement at predicting time required for tumour removal and kidney reconstruction during partial nephrectomy.

METHODS: A consecutive cohort of partial nephrectomy patients treated at The Ottawa Hospital, a tertiary care uro-oncological centre, was retrospectively reviewed. Preoperative axial images were reviewed by four experienced urological oncologists who independently rated the complexity of a partial nephrectomy from 1-10 to generate a clinical judgement score. Two independent reviewers determined the RENAL, PADUA, and C-index scores. The time to complete tumour resection and renal reconstruction during partial nephrectomy was prospectively recorded.

RESULTS: During the study period, 104 partial nephrectomies were performed. The mean partial nephrectomy complexity score based on clinical judgement was 3.4 (standard deviation [SD] 2.1) out of 10. There was good agreement between surgeons in assessing tumour complexity (intraclass correlation coefficient 0.72; 95% confidence interval [CI] 0.65, 0.78). The mean RENAL score was 6.7 (SD 1.6) out of a maximum of 12, the mean PADUA score was 8.5 (SD 1.5) out of a maximum of 14, and the mean C-index score was 3.8 (SD 2). Mean resection and reconstruction time was 24 minutes (SD 10 minutes). The correlation between clinical judgement score and time was 0.27 (p=0.005). The correlation between renal tumour scoring systems and time was 0.20 (p=0.04) for RENAL, 0.21 (p=0.03) for C-index, and 0.26 (p=0.007) for PADUA. RENAL and PADUA scores were significantly associated with surgical and total complications.

CONCLUSIONS: The majority of variance in ischemia time is not explained by clinical judgement or renal tumour scoring systems. Renal tumour scoring systems were not better than the clinical judgement of urological oncologists at predicting ischemia time during partial nephrectomy.