Patient Reported Outcome Measures in Pediatric Anterior Cruciate Ligament Reconstruction: Does PROMIS Correlate with Pedi-ikdc?

Background: The Pediatric International Knee Documentation Committee (Pedi-IKDC) is a well-established patient reported outcome (PRO) measure used in knee and sports surgery. Recently, the computer adaptive Patient-Reported Outcomes Measurement Information System (PROMIS) test has emerged as an alternative measure of patient function in this realm, but it is unclear if it captures information similar to the Pedi-IKDC and other PROs. The purpose of this study was to evaluate the strength of correlation between PROMIS and Pedi-IKDC scores for pediatric anterior cruciate ligament reconstruction (ACLR) patients during the postoperative period.

Methods: Pediatric ( <18yo) patients undergoing primary ACLR at a single urban tertiary care children’s hospital were identified. Patients completing both PROMIS and Pedi-IKDC within 2 weeks of each other were included. PROMIS domains including Physical Function, Anxiety, Depressive Symptoms, Fatigue, Peer Relationships, and Pain Interference were compared with the Pedi-IKDC using Pearson or Spearman correlations. Correlations were performed between Pedi-IKDC and PROMIS domains within subgroups based on timing of survey completion post-operatively ( <6 weeks, 6-12 weeks, 3-6 months, 6-9 months, and >9 months). Multivariable robust regression modeling was performed to generate an equation of best fit to calculate a patient’s projected Pedi-IKDC result from PROMIS subdomains.

Results: Study criteria were met by 150 patients. The cohort averaged 15.0 ± 2.2 years of age, was 50.7% male and underwent predominantly quadriceps (55.3%) or hamstring (36.7%) tendon ACLR. Score correlations appeared stronger with increased follow-up (Table 1). Both PROMIS Physical Function and Pain scores demonstrated moderate correlation to IKDC scores at 6-9 months (R=0.689, p<0.001; R=-0.556, p<0.001) and >9 month (R=0.487, p=0.001; R=-0.429, p=0.003) post-operatively. Across all timepoints, Pedi-IKDC and PROMIS Physical function demonstrated a strong correlation (R=0.844, p<0.001) while PROMIS Pain interference showed a moderate correlation (R=-0.541, p<0.001). A conversion equation for predicting Pedi-IKDC score was generated from PROMIS Physical Function and Pain Interference subdomains based on forward stepwise variable selection for robust regression model. This model demonstrates strong predictive ability for Pedi-IKDC (R^2=0.752, p<0.001) (Figure 1).

Conclusion: The results from this study suggest that Pedi-IKDC demonstrates moderate to strong correlation with PROMIS physical function and pain interference domains following pediatric ACLR. Together, these two PROMIS domains also provide a reasonably strong prediction of a patient’s Pedi-IKDC score at a similar postoperative timepoint. These findings serve to facilitate cross-study outcome comparisons and can aid in the reduction of patient survey burden. Further work will be necessary to confirm these results across a broader patient cohort with longer periods of postoperative follow-up.