Reporting of censoring in oncology trials lacks transparency, study shows
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Cancer clinical trials supporting FDA approvals significantly differ in reporting of withdrawal of consent or loss to follow-up and early drug discontinuation for adverse events, according to study results.
The findings, published in Journal of the National Comprehensive Cancer Network, indicated a need to report censoring in a more transparent way and divulge sensitivity analysis using alternative censoring guidelines.
“This will improve clarity for clinicians and patients when making treatment decisions and for payers making reimbursement decisions,” Brooke E. Wilson, MBBS, MSc, researcher in the division of medical oncology and hematology in the department of medicine at Princess Margaret Cancer Center, and colleagues wrote.
Rationale, methodology
Censoring rules vary across oncology clinical trials and no defined standards exist, so Wilson and colleagues aimed to describe the planned handling and transparency of censoring data in 81 oncology trials. The researchers compared early drug discontinuation and withdrawal of consent or loss to follow-up in experimental and control groups. They gathered data from FDA archives to identify approvals of solid tumor therapies and their associated clinical trials conducted between 2015 and 2019 and performed logistic regression to identify trial characteristics associated with withdrawal of consent or loss to follow-up.
Key findings
More than half (59%) of clinical trials adequately defined censoring rules, but only 17% clearly reported proportions of censored participants.
The control group experienced a higher proportion of withdrawal of consent or loss to follow-up vs. the experimental group (3.9% vs. 2.5%; beta-coefficient = 2.2; 95% CI, 3.1 to 1.3).
The experimental group experienced a higher number of early drug discontinuations in 61% of clinical trials; however, researchers observed no statistically significant difference in the proportion of early drug discontinuations between the two groups (mean, 21.6% vs. 19.9%; beta-coefficient = 0.27; 95% CI, 0.32 to 0.87).
Moreover, researchers observed a higher percentage of early drug discontinuations associated with adverse events in the experimental group (mean, 13.2% vs. 8.5%; beta-coefficient = 1.5; 95% CI, 0.57-2.45), whereas higher rates of withdrawal of consent or loss to follow-up occurred in the control group (OR = 10.1; P < .001) as well as in open label trials (OR = 3; P = .08).
Implications
“We hope that our findings will prompt investigators and journals to report early drug discontinuation, withdrawal of consent, loss to follow-up and censoring more transparently in trial publications,” Wilson said in a press release. “This would allow patients and clinicians to make more informed decisions regarding potential benefits of a treatment. Regulatory authorities and journals can play a leadership role in mandating improved transparency and ensuring that censoring data be made publicly available.”
For more information:
Brooke E. Wilson, MBBS, MSc, can be reached at Princess Margaret Cancer Center, 610 University Ave., 7-305W, Toronto, ON M5G 2M9, Canada; email: drbrookewilson@icloud.com.
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