Determining Success or Failure After Foot and Ankle Surgery Using Patient Acceptable Symptom State (PASS) and Patient Reported Outcome Information System (PROMIS)

Background: As the role of generic patient-reported outcomes (PROs) expands, important questions remain about their interpretation. In particular, how the Patient Reported Outcome Measurement Instrumentation System (PROMIS) t score values correlate with the patients' perception of success or failure (S/F) of their surgery is unknown. The purposes of this study were to characterize the association of PROMIS t scores, the patients' perception of their symptoms (patient acceptable symptom state [PASS]), and determination of S/F after surgery.

Methods: This retrospective cohort study contacted patients after the 4 most common foot and ankle surgeries at a tertiary academic medical center (n = 88). Patient outcome as determined by phone interviews included PASS and patients' judgment of whether their surgery was a S/F. Assessment also included PROMIS physical function (PF), pain interference (PI), and depression (D) scales. The association between S/F and PASS outcomes was evaluated by chi-square analysis. A 2-way analysis of variance (ANOVA) evaluated the ability of PROMIS to discriminate PASS and/or S/F outcomes. Receiver operator curve (ROC) analysis was used to evaluate the ability of pre- (n = 63) and postoperative (n = 88) PROMIS scores to predict patient outcomes (S/F and PASS). Finally, the proportion of individuals classified by the identified thresholds were evaluated using chi-square analysis.

Results: There was a strong association between PASS and S/F after surgery (chi-square <0.01). Two-way ANOVA demonstrated that PROMIS t scores discriminate whether patients experienced positive or negative outcome for PASS ( P < .001) and S/F ( P < .001). The ROC analysis showed significant accuracy (area under the curve > 0.7) for postoperative but not preoperative PROMIS t scores in determining patient outcome for both PASS and S/F. The proportion of patients classified by applying the ROC analysis thresholds using PROMIS varied from 43.0% to 58.8 % for PASS and S/F.

Conclusions: Patients who found their symptoms and activity at a satisfactory level (ie, PASS yes) also considered their surgery a success. However, patients who did not consider their symptoms and activity at a satisfactory level did not consistently consider their surgery a failure. PROMIS t scores for physical function and pain demonstrated the ability to discriminate and accurately predict patient outcome after foot and ankle surgery for 43.0% to 58.8% of participants. These data improve the clinical utility of PROMIS scales by suggesting thresholds for positive and negative patient outcomes independent of other factors.

Level of evidence: II, prospective comparative series.