Predictors of PROMIS Physical Function at 2 Years following Knee Surgery

PROMIS physical function and pain perform poorly psychometrically in patients undergoing medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to assess the validity, floor and ceiling effects, and dimensionality of PROMIS Physical Function (PF) and Pain compared to legacy patient reported outcome (PRO) measures in patients undergoing medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Patients who underwent MPFL reconstruction between 2018 to 2020 were retrospectively reviewed. Preoperatively, patients completed the IKDC, VR-12, Kujala, SF-12, KOOS JR, PROMIS PF and Pain surveys. Inter-survey convergence was assessed with Spearman correlations. Psychometric analysis included investigations of inter-survey convergent validity, intra-survey floor and ceiling effects, and Rasch analyses with person-item fit and iterative question elimination model fit testing.

RESULTS

A total of 76 patients (mean age: 22.6 ± 8.4 years) who completed preoperative surveys were included (compliance: 91.7-96.2%). Preoperatively, age was significantly associated with both PROMIS PF (coefficient:  - 0.291, P = 0.005) and Pain scores (coefficient: 0.294, P = 0.002). PROMIS PF had a Very Good correlation with IKDC and PROMIS Pain had a Very Good correlation with KOOS JR. Other correlations ranged from Poor to Good. No significant floor or ceiling effects were observed for any PRO. On iterative question elimination Rasch modelling, only two questions from PROMIS PF remained after 6 rounds of elimination while PROMIS Pain had no questions remaining after 3 rounds of elimination.

CONCLUSION

Preoperative PROMIS PF and Pain provided only Fair to Good correlations with most legacy PROs. Although no significant floor and ceiling effects were observed, PROMIS PF and Pain did not perform well psychometrically in this population of patients undergoing MPFL reconstruction. These results suggest PROMIS questionnaires should be used with caution in this population, especially if used in isolation, when discussing clinical expectations with patients. The authors recommend continued use of legacy PROs specific to assessment of patellar instability and function that have established validity in patellar instability populations.

LEVEL OF EVIDENCE

Level IV.

PROMIS cluster analysis predicts two-year outcomes in knee surgery patients

Aims & objectives

Meaningful clinical interpretation of orthopaedic patient-reported outcome scores remains challenging. Grouping scores may be more meaningful than individual score analysis. The purpose of this study was to determine if grouping knee surgery patients into four preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) clusters would have prognostic value for two-year postoperative outcomes.

Materials & methods

488 of 697 (70%) patients undergoing elective knee surgery at a single urban institution were enrolled in an orthopaedic registry and completed two-year follow up. Patients were administered questionnaires for PROMIS, International Knee Documentation Committee Score (IKDC), Marx Activity Rating Scale (MARS), and Surgical Satisfaction (SSQ-8). A k-means cluster analysis was performed to identify preoperative PROMIS clusters. Chi-square or Kruskal-Wallis tests were conducted for bivariate analyses. Least-squares multiple linear regression models were performed to identify if cluster group was an independent predictor.

Results

Cluster analysis revealed four clusters of patients. Psychological distress was most significant in determining classification. More impaired clusters were associated with higher rates of arthroplasty, African American race, preoperative opioid use, lower income, higher comorbidity index, and other sociodemographic and operative factors. Worse preoperative cluster status was associated with higher chance of achieving minimally clinically important change (MCID) on all metrics except PROMIS Pain Interference (PI), IKDC, and MARS. Multivariable analysis confirmed better preoperative cluster as predictive of better PROMIS Physical Function (PF), PI, IKDC scores, and satisfaction. Worse preoperative cluster was predictive of greater improvement on PF and PI but not IKDC.

Conclusion

Preoperative PROMIS clusters have prognostic value in predicting outcomes for knee surgery patients. Better preoperative cluster function predicts superior outcomes. While worse preoperative cluster predicts worse outcome, all clusters still significantly improve, so worse preoperative cluster is not a contraindication to surgery.

Recovery Curve for Patients With Pilon Fractures Using Patient-Reported Outcome Measurement Information System

BACKGROUND

The time frame in which patients can expect functional improvement after open reduction internal fixation (ORIF) of pilon fractures is unclear. The purpose of this study was to determine the trajectory and rate at which patients' physical function improves up to 2 years postinjury.

METHODS

The patients studied sustained a unilateral, isolated pilon fractures (AO/OTA 43B/C) and followed at a level 1 trauma center over a 5-year period (2015-2020). Patient-Reported Outcomes Measurement Information Systems (PROMIS) Physical Function (PF) scores from these patients at defined follow-up times of immediately, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery defined the cohorts and were retrospectively studied.

RESULTS

There were 160 patients with PROMIS scores immediately postoperatively, 143 patients at 6 weeks, 146 patients at 12 weeks, 97 at 24 weeks, 84 at 1 year, and 45 at 2 years postoperatively. The average PROMIS PF score was 28 immediately postoperatively, 30 at 6 weeks, 36 at 3 months, 40 at 6 months, 41 at 1 year, and 39 at 2 years. There was a significant difference between PROMIS PF scores between 6 weeks and 3 months (P < .001), and between 3 and 6 months (P < .001). Otherwise, no significant differences were detected between consecutive time points.

CONCLUSION

Patients with isolated pilon fractures demonstrate the majority of their improvement in terms of physical function between 6 weeks and 6 months postoperatively. No significant difference was detected in PF scores after 6 months postoperatively up to 2 years. Furthermore, the mean PROMIS PF score of patients 2 years after recovery was approximately 1 SD below the population average. This information is helpful in counseling patients and setting expectations for recovery after pilon fractures.

LEVEL OF EVIDENCE

Level III, prognostic.

A High-Sensitivity International Knee Documentation Committee Survey Index From the PROMIS System: The Next-Generation Patient-Reported Outcome for a Knee Injury Population

BACKGROUND

Patient-reported outcomes (PROs) measure progression and quality of care. While legacy PROs such as the International Knee Documentation Committee (IKDC) survey are well-validated, a lengthy PRO creates a time burden on patients, decreasing adherence. In recent years, PROs such as the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function and Pain Interference surveys were developed as computer adaptive tests, reducing time to completion. Previous studies have examined correlation between legacy PROs and PROMIS; however, no studies have developed effective prediction models utilizing PROMIS to create an IKDC index. While the IKDC is the standard knee PRO, computer adaptive PROs offer numerous practical advantages.

PURPOSE

To develop a nonlinear predictive model utilizing PROMIS Physical Function and Pain Interference to estimate IKDC survey scores and examine algorithm sensitivity and validity.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

The MOTION (Military Orthopaedics Tracking Injuries and Outcomes Network) database is a prospectively collected repository of PROs and intraoperative variables. Patients undergoing knee surgery completed the IKDC and PROMIS surveys at varying time points. Nonlinear multivariable predictive models using Gaussian and beta distributions were created to establish an IKDC index score, which was then validated using leave-one-out techniques and minimal clinically important difference analysis.

RESULTS

A total of 1011 patients completed the IKDC and PROMIS Physical Function and Pain Interference, providing 1618 complete observations. The algorithms for the Gaussian and beta distribution were validated to predict the IKDC (Pearson = 0.84-0.86; R² = 0.71-0.74; root mean square error = 9.3-10.0).

CONCLUSION

The publicly available predictive models can approximate the IKDC score. The results can be used to compare PROMIS Physical Function and Pain Interference against historical IKDC scores by creating an IKDC index score. Serial use of the IKDC index allows for a lower minimal clinically important difference than the conventional IKDC. PROMIS can be substituted to reduce patient burden, increase completion rates, and produce orthopaedic-specific survey analogs.