Preoperative PROMIS Scores Predict Postoperative Success in Foot and Ankle Patients

Background: The use of patient-reported outcomes continues to expand beyond the scope of clinical research to involve standard of care assessments across orthopedic practices. It is currently unclear how to interpret and apply this information in the daily care of patients in a foot and ankle clinic. We prospectively examined the relationship between preoperative patient-reported outcomes (PROMIS Physical Function, Pain Interference and Depression scores), determined minimal clinical important differences for these values, and assessed if these preoperative values were predictors of improvement after operative intervention.

Methods: Prospective collection of all consecutive patient visits to a multisurgeon tertiary foot and ankle clinic was obtained between February 2015 and April 2016. This consisted of 16 023 unique visits across 7996 patients, with 3611 new patients. Patients undergoing elective operative intervention were identified by ICD-9 and CPT code. PROMIS physical function, pain interference, and depression scores were assessed at initial and follow-up visits. Minimum clinically important differences (MCIDs) were calculated using a distribution-based method. Receiver operating characteristic (ROC) curves were calculated to determine whether preoperative PROMIS scores were predictive of achieving MCID. Cutoff values for PROMIS scores that would predict achieving MCID and not achieving MCID with 95% specificity were determined. Prognostic pre- and posttest probabilities based off these cutoffs were calculated. Patients with a minimum of 7-month follow-up (mean 9.9) who completed all PROMIS domains were included, resulting in 61 patients.

Results: ROC curves demonstrated that preoperative physical function scores were predictive of postoperative improvement in physical function (area under the curve [AUC] 0.83). Similarly, preoperative pain interference scores were predictive of postoperative pain improvement (AUC 0.73) and preoperative depression scores were also predictive of postoperative depression improvement (AUC 0.74). Patients with preoperative physical function T score below 29.7 had an 83% probability of achieving a clinically meaningful improvement in function as defined by MCID. Patients with preoperative physical function T score above 42 had a 94% probability of failing to achieve MCID. Patients with preoperative pain above 67.2 had a 66% probability of achieving MCID, whereas patients with preoperative pain below 55 had a 95% probability of failing to achieve MCID. Patients with preoperative depression below 41.5 had a 90% probability of failing to achieve MCID.

Conclusion: Patient-reported outcomes (PROMIS) scores obtained preoperatively predicted improvement in foot and ankle surgery. Threshold levels in physical function, pain interference, and depression can be shared with patients as they decide whether surgery is a good option and helps place a numerical value on patient expectations. Physical function scores below 29.7 were likely to improve with surgery, whereas those patients with scores above 42 were unlikely to make gains in function. Patients with pain scores less than 55 were similarly unlikely to improve, whereas those with scores above 67 had clinically significant pain reduction postoperatively. Reported prognostic cutoff values help to provide guidance to both the surgeon and the patient and can aid in shared decision making for treatment.

Level Of Evidence: Level II, prognostic study.