Trends in Postoperative Infection Rates and Their Relationship to Glycosylated Hemoglobin Levels in Diabetic Patients Undergoing Foot and Ankle Surgery

The association of hyperglycemia with postoperative infectious complications after foot and ankle surgery has been well studied. However, many surgeons in their current practice use the somewhat arbitrary cutoff of 7% glycosylated hemoglobin (HbA1c) as the level above which surgery is considered unsafe and conducive to complications. Our goal in the present study was to assess the relationship between the HbA1c levels and the rate of postoperative infection to begin to determine whether 7% is a suitable cutoff or whether this level needs to be reevaluated. Furthermore, we were interested in the general trends relating to the infection rates and preoperative HbA1c levels. Our preliminary, subjective, analysis has indicated that infection rates increase steadily as the HbA1c increases toward 7.3%, increase rapidly at an HbA1c of 7.3% to 9.8%, and then level off. Additional study is warranted to better understand the role played by other covariates in determining the infection rate and to investigate whether patient selection has influenced the appearance of decreased infection rates at high HbA1c levels. Additional study could also assess similar relationships for other types of complication, such as nonunion, and perhaps examine different foot and ankle procedures in isolation.