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Surrogate End Points Are Associated With Favorable Results in Hip and Knee Arthroplasty Randomized Controlled Trials
Nadim Barakat1, James R Temple2, Logan S Carpenter2
1Department of Orthopaedic Surgery, Virginia Commonwealth University, Richmond, Virginia.
Background:
Surrogate end points, such as radiographic measurements or biomarkers, are often used as substitutes for clinically meaningful outcomes in arthroplasty research. However, they may not accurately reflect how a patient feels, functions, or survives, and their reliability in demonstrating true clinical benefits is uncertain. This study assessed whether randomized controlled trials (RCTs) using surrogate end points as primary outcomes were more likely to report favorable results than those using true clinical outcomes.
Methods:
The RCTs on hip and knee arthroplasty published in four leading orthopaedic journals from 2014 through 2023 were systematically identified and analyzed by multiple reviewers. The primary study outcome was classified as a surrogate end point or true clinical outcome. Study results were classified as favorable, neutral, or unfavorable to the control based on statistical significance in the primary outcome. Unadjusted Chi-square analyses were conducted to determine the relationship between primary outcome type and intervention assessment, and regression analyses were used to evaluate adjusted associations.
Results:
Of the 566 articles, 243 (42.9%) used surrogate end points and 323 (57.1%) used true clinical outcomes as primary outcomes. The RCTs using surrogate primary outcomes were more likely to report favorable results than those using true clinical outcomes (53.1 versus 34.1%). Chi-square analyses revealed a statistically significant association between the type of primary outcome and intervention assessment, with RCTs using surrogate primary outcomes demonstrating a higher likelihood of reporting favorable interventions (relative risk, 1.56; 95% confidence interval, 1.29 to 1.89; P < 0.001). The RCTs focused on surgical technology were more likely to utilize surrogate primary outcomes (relative risk, 1.52; 95% confidence interval, 1.27 to 1.83; P < 0.001). These associations remained significant after adjustment for study characteristics.
Conclusions:
The use of surrogate end points as primary outcomes in hip and knee arthroplasty RCTs is significantly associated with reporting favorable interventions compared to those using true clinical outcomes.
