Clinician V ersus Nomogram Predicted Estimates of Kidney Stone Recurrence Risk

Abstract

Purpose: Kidney stone recurrence rates vary between patients. A patient's risk informs the frequency and intensity of preventative interventions. Clinicians routinely use clinical experience to estimate risk. We sought to compare clinician estimated recurrence risk with the recurrence of kidney stones (ROKS) nomogram. Materials and Methods: We surveyed members of the Endourological Society with clinical expertise in kidney stones. Respondents estimated the risk of recurrence for patients in three clinical vignettes corresponding to low, intermediate, and high recurrence risk from the nomogram. Clinician estimates were compared with ROKS estimates. Results: The majority of the 318 respondents were from North America (n = 127, 40%). The most commonly estimated recurrence was 50% at 5 years. The respondents' estimates were significantly different from the ROKS predicted recurrence rate for all cases (Case 1, 50% vs 93% p < 0.0001; Case 2, 50% vs 60% p < 0.0001; Case 3, 60% vs 22% p < 0.0001). The ROKS predicted estimates ranged from 22% to 93%, whereas the median urologist-derived 5-year risk estimates for each case ranged from 50% to 60%. The median range of estimates by respondents across cases was 20%, narrower than the 71% for the ROKS nomogram. The majority of respondents (95%) do not use nomograms in practice, mostly because of lack of awareness of useful nomograms (59%). Conclusions: This study suggests that clinicians may not be able to distinguish those with high and low recurrence risk when compared with peers and when compared with a nomogram. Clinical decision support tools are needed to enable clinicians to better estimate stone recurrence risk.

Keywords: kidney calculi; nephrolithiasis; nomograms; urinary calculi; urolithiasis.

FIG. 1.

Estimated chance of recurrence of symptomatic kidney stone episode within 5 years by number of respondents. Each panel represents 1 of the 3 numbered cases. Means were Case 1, 48%; Case 2, 53%; Case 3, 58%. ROKS nomogram estimates (red arrows) were Case 1, 93%; Case 2, 60%; Case 3, 22%. All differences between respondent and ROKS estimates were significant, p < 0.0001. ROKS = recurrence of kidney stones. Color images are available online.

FIG. 2.

Absolute difference between maximum and minimum estimated recurrence rate between cases for each participant, grouped by size of estimated range. Absolute difference between ROKS nomogram estimates of recurrence rate between cases labeled in red. ROKS = recurrence of kidney stones. Color images are available online.