Why comprehensive metrics matter in patient outcome studies
Patient-centered care and patient outcomes research are becoming increasingly prevalent. With growing internet access, patients can now easily access research that informs clinical decision-making, and published research must provide both patients and clinicians with clear primary endpoints and outcomes.
Published clinical research often analyzes detailed outcome measures, such as changes in specific molecular markers before and after an intervention. While these studies benefit clinical decision-making and policy implementation, they often are too complex and specific to offer meaningful insights to patients and their families.
Comprehensive outcome measures, such as mortality, provide a clearer and broader picture of prognosis and expected treatment effects for patients. However, even these outcomes often focus on specific disease groups or limited timeframes, making it difficult to apply the findings to a broader patient population or assess the full effects of policy changes.
Our recent article, “Trends in Survival for Adult Organ Transplantation,” showcases how a longitudinal, comprehensive metric provides more generalizable information on overall patient outcomes compared to more specific clinical data analysis.
Much of the existing data analysis related to measuring the survival of solid organ transplant patients focuses on waitlist survival or post-transplant survival separately. Although these are useful outcomes to measure, one cannot broadly characterize the overall outcomes of transplant candidates. Measuring waitlist or post-transplant survival separately results in a fragmented survival analysis. It does not account for changes in transplant rate or the combined effects of advancements in pre-transplant and post-transplant treatment options.
Instead, in our study, we performed a retrospective intent-to-treat (ITT) analysis for kidney, heart, liver, and lung transplants, where patients were followed from the date of listing on the transplant list to death, regardless of when or if they received a transplant. This approach allowed for a broader analysis of changes in overall mortality for all patients listed on the transplant list in the U.S.
Overall, we found that ITT survival is steadily increasing for liver, heart and lung transplants. This is likely due to improvements in pre-transplant and post-transplant treatments as well as changes in organ allocation policy. Notably, we found that intent-to-treat survival for kidney transplantation had decreased, even with increases in waitlist and post-transplant survival independently. As we discuss, this is likely due to several factors, most notably a declining transplant rate and increased use of marginal donor kidneys, both of which have resulted from the continued “supply-and-demand” issue in kidney transplantation.
Overall, our results indicate that the overall survival rate for kidney transplantation has not improved, and more work is needed to continue bridging the gap between the “supply and demand” of donor kidneys.
When examining current organ allocation policies, understanding broad, patient-centered outcomes such as survival is important because it provides a comprehensive measure of success. As evidenced by our study, studying pre-transplant and post-transplant survival independently may overlook factors such as transplant rates and time spent on the waitlist, which are closely tied to survival and, therefore, are high priorities in determining organ allocation policy. Focusing on ITT survival provides more information about where the focus of organ allocation policy changes should be, allowing for more informed policy decisions and, ultimately, better outcomes from those changes. Studies like ours, which examine broad outcomes and populations, allow patients, providers and policymakers to focus on the big picture and the outcomes that patients and their families care most about. This is equally important for policy decisions as it is for patient education.
Future research to optimize healthcare policy needs to take both comprehensive and detailed outcome measures into account. This approach will help patients and policymakers better understand the full impact of clinical guidelines, guiding more informed policy decisions.
By Grant Patrick, an MS4 medical student at Baylor College of Medicine
