Clinician Versus Nomogram Predicted Estimates of Kidney Stone Recurrence Risk

The overall recurrence rate for patients with kidney stones is high, classically estimated at 30-50% at 10 years. However, the rate of recurrence for individuals varies. A patient at higher risk of recurrence may benefit more from preventative dietary and pharmacologic interventions. Conversely, a patient at a lower risk of recurrence might be unnecessarily subjected to preventative interventions or surveillance with their associated side effects. Accurately estimating an individual’s risk of stone recurrence, therefore, affects their clinical care.

Nomograms have been developed to estimate the risk of an individual’s stone recurrence. The most well-validated nomogram is the Recurrence of Kidney Stones (ROKS) nomogram. In this study, we sought to compare clinician estimates to ROKS nomogram estimates of kidney stone recurrence rates. We also assessed how clinicians would treat high and low-risk patients differently.

To this end, we performed a survey of Endourology Society members. We collected demographic information and presented clinicians with 3 clinical vignettes of first-time stone formers and asked for an estimate of kidney stone recurrence risk. We compared their responses to ROKS nomogram estimates. We also asked about their use of nomograms in practice, and how their clinical management would change for high or low-risk patients.

Our 318 survey responses were mostly Endourology fellowship-trained, with more than half indicating a high proportion of stone disease in their practice. This experienced cohort reported a significantly different estimate of stone recurrence compared to the ROKS nomogram for all three vignettes. Interestingly, while the ROKS nomogram estimates for the three vignettes differed by 71%, the median difference in clinician estimates was only 20%. This shows a narrower range of clinician estimates for recurrence rate and suggests that clinicians have decreased discriminatory ability compared to the ROKS nomogram. Only 5% of respondents used nomograms in practice, mostly due to an opinion that they would not be useful or not knowing of any useful nomograms. Clinicians reported that their workup and preventative treatment would be more intense for patients at a high risk of recurrence.

These findings indicate a discordance between clinician estimates of stone recurrence and the leading available recurrence risk nomogram (ROKS). The discrepancy may be due to the narrower range of estimates provided by clinicians. Our findings indicated that the estimated recurrence risk is important to patient care, as clinicians reported modifying their investigations and surveillance based on a perceived estimate of risk. Integration of recurrence risk nomograms into clinical workflows, such as through direct embedding into electronic health records, is one method to improve clinician use of these tools. Accurate estimation of kidney stone recurrence risk will help clinicians and patients individualize the level of intervention and investigation required, and improve patient care.

Written by: Connor M Forbes, Allison B McCoy, Ryan S Hsi

Department of Urology, Vanderbilt University Medical Center, Nashville, Tennessee, USA., Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

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