An evaluation of the use of retrospectively acquired preoperative AOFAS clinical rating scores to assess surgical outcome after elective foot and ankle surgery

Abstract

The use of retrospectively acquired preoperative AOFAS rating scores in clinical research to assess the outcomes of elective foot and ankle surgery has not been validated. The data obtained utilizing this methodology may misrepresent the results and lead to spurious conclusions. This investigation compared preoperative AOFAS Ankle-Hindfoot scores obtained before and after surgery from patients who had undergone elective surgery to determine if retrospectively acquired scores match those collected prospectively. Only two out of 47 patients (4%) recalled identical AOFAS scores. The mean difference between the preoperative scores (preoperative score obtained after surgery minus preoperative score obtained before surgery) was -5.3 points. Fifteen patients (32%) had preoperative scores that differed by 20 points or more. Kappa statistics found little agreement among the five elements that comprised the two preoperative scores when responses obtained before and after surgery were compared to one another. The results suggest that preoperative clinical rating scores obtained after elective surgery are a poor predictor of the patient's preoperative condition and that studies which employ retrospectively acquired preoperative AOFAS clinical rating scores may overestimate the benefit of surgery.