Potential for Bias and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scoring System.

BACKGROUND: The American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scoring System (AOFAS-AH) has not been validated and has significant risk for researcher bias, given that 40 out of 100 points are assessed by study staff subjectively. The purpose of this study is to evaluate its recent use in the orthopaedic literature to determine the percentage of previously published studies for which study conclusions would be changed if the AOFAS-AH scores were artificially altered, representing the effect of a systematic researcher bias.

MATERIALS AND METHODS: Articles from January 2012 and February 2015 in three orthopaedic journals were queried for use of the AOFAS-AH. Quantities of 4, 8, or 12 points were added to or subtracted from mean AOFAS-AH scores for each study while otherwise maintaining the reported standard deviation to simulate a researcher bias when scoring the subjective sections. Statistical analysis was performed with the adjusted AOFAS-AH mean scores in order to elucidate a potential "reversal" in statistical significance and conclusion.

RESULTS: A 1582 original research articles were published during this time period. 128 articles utilized the AOFAS-AH score. 30 articles (23.4%) reported the required statistical data to permit manipulation of AOFAS-AH scores. Nine of the 30 articles (30%) had a reversal following a manipulation of 12 or fewer points. Seven (5.5%) reported the blinding status of the researchers.

CONCLUSION: The potential for bias is high with the AOFAS-AH and its continued is questionable. Researchers utilizing the AOFAS-AH should at a minimum appropriately blind study staff and consider pre-study clarification of subjective terminology.

LEVELS OF EVIDENCE: Level IV.