An Exploratory Factor Analysis of the National Institutes of Health Patient-Reported Outcomes Measurement Information System and the Single Assessment Numeric Evaluation in Knee Surgery Patients

Introduction: Patient-Reported Outcomes (PROs) have been suggested for use in measuring treatment effectiveness. To minimize patient burden, two approaches have been proposed: An orthopedic-specific Single Assessment Numeric Evaluation (SANE) or computer adaptive testing methods such as the National Institutes of Health (NIH) Patient-Reported Outcomes Measurement Information System (PROMIS). The goal of this work was to examine the constructs measured by the SANE and PROMIS system in a military orthopedic population undergoing knee surgery. Materials and Methods: In 732 patients and 2,166 complete observations, the SANE-Knee PRO and PROMIS surveys for Depression, Anxiety, Pain Interference, Sleep Disturbance, and Physical Function were obtained. A correlation matrix between the PROs was calculated, the number of latent factors to extract was determined via parallel plot, and the final principal axis exploratory factor analysis was performed. Results: The parallel plot analysis indicated that two latent factors existed. One latent factor corresponded to measures of psychological distress (PROMIS Sleep Disturbance, Depression, and Anxiety) and the second latent factor corresponded to physical capability (SANE, PROMIS Physical Function, Pain Interference, and Sleep Disturbance). Both PROMIS Physical Function (0.83) and Pain Interference (-0.80) more strongly weigh on the physical capability latent factor than SANE (0.69). Conclusions: In a knee surgical population, the SANE, PROMIS Physical Function, and PROMIS Pain Interference measure the same human dimension of physical capability; however, PROMIS Physical Function and Pain Interference may measure this construct more effectively in isolation. The SANE may be a more viable option to gauge physical capability when computer adaptive testing is not possible.