Prevalence of unnecessary kidney function exclusion criteria in urologic oncology clinical trials

Clinical trials play a pivotal role in advancing treatments for people with cancer, but often struggle with low enrollment. Unnecessarily including kidney function eligibility criteria when a trial's interventions do not have any potential kidney effects may contribute to this problem by needlessly limiting the pool of eligible patients, adding complexity to the patient screening process, and raising issues of inequitable access to trials. For these reasons, we applied custom natural language processing to assess renal function eligibility criteria, and the appropriateness of these exclusions, within phase 3 urologic oncology trials.

We accessed all phase 3 urologic oncology trials registered on ClinicalTrials.gov from 2007 to 2021. We used a custom natural language processing script to extract kidney function requirements (e.g., creatinine, GFR) from trial free-text records. For each trial, we manually coded whether any trial intervention affected renal function or was renally excreted. Additionally, we recorded the formula used to calculate GFR in each trial.

Of 850 trials, 299 (35%) listed kidney function eligibility restrictions, and 432 (51%) tested an intervention with possible renal effects. Of the 299 trials with kidney function exclusions, 124 (41%) tested interventions with no kidney effects.

There is a major disconnect in urologic oncology clinical trials between renal function exclusions and potential harm to the kidneys from the tested interventions. Standardizing eligibility criteria and restricting enrollment based on renal function only when necessary has the potential to increase the success, access, and applicability of clinical trials.