Identification and Exploration of Response Shift in Patient Reported Outcome Measures following Anterior Cruciate Ligament Reconstruction
Abstract
Purpose: The overall purpose of this thesis was to investigate response shift effects in patient reported outcome measures (PROMs) of symptoms, function, and quality of life after anterior cruciate ligament (ACL) injury and reconstruction.
Methods: This thesis includes three studies. Study 1 was a prospective cohort study designed with then-test methodology (using recalled and actual pre-operative scores) to detect the recalibration mechanism of response shift in the reporting of the two most common PROMs used with patients after ACL reconstruction. Study 2 was a qualitative study meant to elucidate young athletes’ definitions and perceptions of quality of life following an ACL injury, prior to surgical intervention. Study 3 was a one-year follow-up of Study 2 which allowed for detailed exploration of young athletes’ definition of quality of life and priorities one year after ACLR using qualitative methods and incorporating the then-test for self-reported quality of life ratings.
Results: Significant response shift effects were detected in patient reported outcomes after ACL reconstruction. Change in patient reported outcomes (treatment effects) were larger when recalled pre-operative scores were used in place of actual pre-operative scores (i.e., when both pieces of the change score were completed at the same time), suggesting that pre-post treatment effects may be commonly underestimated for PROMs. Patient perspectives on quality of life changed from pre- to post-operative through processes of recalibration, reframing, reprioritization, reconceptualization, and self-reflection.
Conclusions: Response shift was detected in PROMs from pre-operative to one year post-operative following ACLR, at both a group and individual level. Mechanisms of recalibration, reprioritization, and reconceptualization were identified as contributing to response shift. Overall, this work calls into question the utility of traditional pre-post intervention change scores for PROMs following ACLR, highlighting the need for novel approaches to subjective outcome assessment and rigorous studies that can accurately evaluate both patient reported outcomes and patient-important event outcomes.