Defining the Patient Acceptable Symptom State (PASS) for PROMIS After Total Ankle Replacement
Authors: Shaffrey Isabel , Conti Matthew S. , Nguyen Joseph T. , Ellis Scott J. , Cody Elizabeth A. , Demetracopoulos Constantine , Henry Jensen K. 
Published: December 2023

Category:

Ankle Arthritis; Other

Introduction/Purpose:

Patient-reported outcomes (PROs), such as PROMIS, are a key element of evaluating success after total ankle replacement (TAR). To date, most PROs are described using absolute values or parameters like the minimum clinically important difference. However, these interpretations do not explicitly tell the surgeon the most important factor of postoperative success: is the patient satisfied with their outcome after TAR? The patient acceptable symptom state (PASS) is a novel PRO metric that attempts to bridge this gap. PASS represents the symptom threshold above which patients consider themselves well. This study aimed to establish the PROMIS thresholds for PASS in a primary cohort of TAR patients. We hypothesized that TAR patients would meet PASS and that PASS would vary with demographic variables.

Methods:

This is a single-institution retrospective cohort study of primary TAR patients (n=127; mean age 63.2 years; mean BMI 29.0 kg/m2; 58% male) with preoperative and 2-year postoperative PROMIS scores (domains: Physical Function, Pain Interference, Pain Intensity, Global Mental Health, Global Physical Health, & Depression). At 2 years postoperatively, patients also answered 2 PASS anchor questions with Likert-scale responses: 1) Are you satisfied with the results of your surgery?; and 2) the Delighted- Terrible symptom scale. PASS thresholds with 95% confidence intervals (CI) were calculated using the anchors “Very satisfied” or “Satisfied” for question 1 and “Delighted,” “Pleased,” or “Mostly Satisfied” for question 2. Using bootstrapping technique with 1000 iterations, the Youden Index was then calculated to determine the best coordinates of specificity and sensitivity to maximize the Area Under the Curve (AUC). Finally, we analyzed preoperative variables (demographics, clinical/surgical data, and preoperative PROMIS scores) on the likelihood of achieving PASS.

Results:

There was a strong association between PASS thresholds and PROMIS domains, especially Physical Function (PASS threshold >44.7, AUC 0.883), Pain Interference (< 56.0, AUC 0.940), and Pain Intensity (< 48.4, AUC 0.936). Covariate stratification demonstrated that the likelihood of achieving PASS was not affected by age, race, gender, ASA score, or BMI. PASS was less likely to be achieved by patients who had undergone prior orthopaedic surgery (P=0.013). Patients with diabetes mellitus and peripheral vascular disease were less likely to meet PASS for Physical Function (P=0.010, P=0.037), but did meet PASS for Pain domains. Patients with worse preoperative Physical Function and Depression scores were less likely to meet PASS for Physical Function postoperatively (P=0.028, P=0.041), but achieved similar PASS for Pain Interference and Pain Intensity domains.

Conclusion:

After TAR, the ability to reach the postoperative PASS was most strongly associated with postoperative pain scores, as evidenced by the Pain Interference and Pain Intensity domains. However, the thresholds for PASS were generally lower than population means. This demonstrates that TAR patients do not need to reach normal pain or physical function levels in order to have an acceptable symptom state postoperatively. Moreover, the ability to achieve PASS was not affected by demographic variables. Further research on PASS is warranted, and may shift how surgeons and researchers evaluate TAR patients pre- and post-operatively.