Defining the Patient Acceptable Symptom State (PASS) for PROMIS After Total Ankle Replacement

Although patient-reported outcomes (PROs), such as the Patient-Reported Outcomes Measurement Information System (PROMIS), are a key element of evaluating success after total ankle replacement (TAR), many do not explicitly state a key factor of postoperative success: is the patient satisfied with their outcome after TAR? The patient acceptable symptom state (PASS) represents the symptom threshold beyond which patients consider themselves well. This study aimed to establish the PROMIS thresholds for the PASS in a primary cohort of TAR patients.

This single-institution study included 127 primary TAR patients with preoperative and 2-year postoperative PROMIS scores. At 2 years postoperatively, patients answered 2 PASS anchor questions (Satisfaction, Delighted-Terrible scale) with Likert-scale responses. PASS thresholds with 95% confidence intervals (CIs) were calculated from PROMIS scores using an anchor-based method. Using a bootstrapping technique with 1,000 iterations, the Youden index was calculated to determine the best specificity and sensitivity coordinates to maximize their combination. Finally, preoperative variables associated with the likelihood of achieving the PASS were assessed.

There was a strong association between PASS thresholds and PROMIS domains, especially Pain Interference (PASS threshold of <56.0, area under the receiver operating characteristic curve [AUC] = 0.940), Pain Intensity (<48.4, AUC = 0.936), and Physical Function (>44.7, AUC = 0.883). The likelihood of achieving the PASS was not affected by age, race, gender, American Society of Anesthesiologists (ASA) class, body mass index, or severity of ankle deformity. Patients with worse preoperative Physical Function and Global Mental Health scores were less likely to meet the PASS threshold for Physical Function postoperatively (p = 0.028 and 0.041).

The ability to reach the PASS after TAR was most strongly associated with postoperative PROMIS pain scores. However, PASS thresholds were generally poorer than population means. This demonstrates that patients do not need to reach normal pain or physical function levels to have an acceptable symptom state after TAR.

Prognostic Level IV . See Instructions for Authors for a complete description of levels of evidence.